Publications
68 results found
Filippou C, Coutts RHA, Stevens DA, et al., 2020, Completion of the sequence of the Aspergillus fumigatus partitivirus 1 genome, Archives of Virology, Vol: 165, Pages: 1891-1894, ISSN: 0304-8608
A Portuguese isolate of Aspergillus fumigatus was found to contain three double-stranded (ds) RNA elements ranging in size from 1.1 to 1.8 kbp and comprising the genome of a strain of Aspergillus fumigatus partitivirus 1 (AfuPV-1) previously thought to contain only the two largest dsRNA elements. The sequence of the smallest dsRNA element is described here, completing the sequence of the AfuPV-1 genome. Sequence analysis of the element revealed an open reading frame encoding a protein of unknown function similar in size and distantly related to elements previously identified in other members of the family Partitiviridae.
Engl C, Jovanovic G, Brackston RD, et al., 2020, The route to transcription initiation determines the mode of transcriptional bursting in E. coli, Nature Communications, Vol: 11, ISSN: 2041-1723
Transcription is fundamentally noisy, leading to significant heterogeneity across bacterial populations. Noise is often attributed to burstiness, but the underlying mechanisms and their dependence on the mode of promotor regulation remain unclear. Here, we measure E. coli single cell mRNA levels for two stress responses that depend on bacterial sigma factors with different mode of transcription initiation (σ70 and σ54). By fitting a stochastic model to the observed mRNA distributions, we show that the transition from low to high expression of the σ70-controlled stress response is regulated via the burst size, while that of the σ54-controlled stress response is regulated via the burst frequency. Therefore, transcription initiation involving σ54 differs from other bacterial systems, and yields bursting kinetics characteristic of eukaryotic systems.
Ye F, Kotta-Loizou I, Jovanovic M, et al., 2020, Structural basis of transcription inhibition by the DNA mimic protein Ocr of bacteriophage T7., eLife, Vol: 9, ISSN: 2050-084X
Bacteriophage T7 infects Escherichia coli and evades the host restriction/modification system. The Ocr protein of T7 was shown to exist as a dimer mimicking DNA and to bind to host restriction enzymes, thus preventing the degradation of the viral genome by the host. Here we report that Ocr can also inhibit host transcription by directly binding to bacterial RNA polymerase (RNAP) and competing with the recruitment of RNAP by sigma factors. Using cryo electron microscopy, we determined the structures of Ocr bound to RNAP. The structures show that an Ocr dimer binds to RNAP in the cleft, where key regions of sigma bind and where DNA resides during transcription synthesis, thus providing a structural basis for the transcription inhibition. Our results reveal the versatility of Ocr in interfering with host systems and suggest possible strategies that could be exploited in adopting DNA mimicry as a basis for forming novel antibiotics.
Kotta-Loizou I, Caston JR, Coutts RHA, et al., 2020, ICTV virus taxonomy profile: chrysoviridae, Journal of General Virology, Vol: 101, Pages: 143-144, ISSN: 0022-1317
Members of the family Chrysoviridae are isometric, non-enveloped viruses with segmented, linear, dsRNA genomes. There are 3–7 genomic segments, each of which is individually encapsidated. Chrysoviruses infect fungi, plants and possibly insects, and may cause hypovirulence in their fungal hosts. Chrysoviruses have no known vectors and lack an extracellular phase to their replication cycle; they are transmitted via intracellular routes within an individual during hyphal growth, in asexual or sexual spores, or between individuals via hyphal anastomosis. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the family Chrysoviridae, which is available at ictv.global/report/chrysoviridae.
Shah UA, Kotta-Loizou I, Fitt BDL, et al., 2020, Mycovirus-Induced Hypervirulence of <i>Leptosphaeria biglobosa</i> Enhances Systemic Acquired Resistance to <i>Leptosphaeria maculans</i> in <i>Brassica napus</i>, MOLECULAR PLANT-MICROBE INTERACTIONS, Vol: 33, Pages: 98-107, ISSN: 0894-0282
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- Citations: 23
Abdoulaye AH, Foda MF, Kotta-Loizou I, 2019, Viruses infecting the plant pathogenic fungus Rhizoctonia solani, Viruses, Vol: 11, ISSN: 1999-4915
The cosmopolitan fungus Rhizoctonia solani has a wide host range and is the causal agent of numerous crop diseases, leading to significant economic losses. To date, no cultivars showing complete resistance to R. solani have been identified and it is imperative to develop a strategy to control the spread of the disease. Fungal viruses, or mycoviruses, are widespread in all major groups of fungi and next-generation sequencing (NGS) is currently the most efficient approach for their identification. An increasing number of novel mycoviruses are being reported, including double-stranded (ds) RNA, circular single-stranded (ss) DNA, negative sense (−)ssRNA, and positive sense (+)ssRNA viruses. The majority of mycovirus infections are cryptic with no obvious symptoms on the hosts; however, some mycoviruses may alter fungal host pathogenicity resulting in hypervirulence or hypovirulence and are therefore potential biological control agents that could be used to combat fungal diseases. R. solani harbors a range of dsRNA and ssRNA viruses, either belonging to established families, such as Endornaviridae, Tymoviridae, Partitiviridae, and Narnaviridae, or unclassified, and some of them have been associated with hypervirulence or hypovirulence. Here we discuss in depth the molecular features of known viruses infecting R. solani and their potential as biological control agents.
Umer M, Liu J, You H, et al., 2019, Genomic, morphological and biological traits of the viruses infecting major fruit trees, Viruses, Vol: 11, ISSN: 1999-4915
Banana trees, citrus fruit trees, pome fruit trees, grapevines, mango trees, and stone fruit trees are major fruit trees cultured worldwide and correspond to nearly 90% of the global production of woody fruit trees. In light of the above, the present manuscript summarizes the viruses that infect the major fruit trees, including their taxonomy and morphology, and highlights selected viruses that significantly affect fruit production, including their genomic and biological features. The results showed that a total of 163 viruses, belonging to 45 genera classified into 23 families have been reported to infect the major woody fruit trees. It is clear that there is higher accumulation of viruses in grapevine (80/163) compared to the other fruit trees (each corresponding to less than 35/163), while only one virus species has been reported infecting mango. Most of the viruses (over 70%) infecting woody fruit trees are positive-sense single-stranded RNA (+ssRNA), and the remainder belong to the -ssRNA, ssRNA-RT, dsRNA, ssDNA and dsDNA-RT groups (each corresponding to less than 8%). Most of the viruses are icosahedral or isometric (79/163), and their diameter ranges from 16 to 80 nm with the majority being 25–30 nm. Cross-infection has occurred in a high frequency among pome and stone fruit trees, whereas no or little cross-infection has occurred among banana, citrus and grapevine. The viruses infecting woody fruit trees are mostly transmitted by vegetative propagation, grafting, and root grafting in orchards and are usually vectored by mealybug, soft scale, aphids, mites or thrips. These viruses cause adverse effects in their fruit tree hosts, inducing a wide range of symptoms and significant damage, such as reduced yield, quality, vigor and longevity.
Kotta-Loizou I, Hadrien P, Saunders K, et al., 2019, Investigating the biological relevance of in vitro identified putative packaging signals at the 5’ terminus of the satellite tobacco necrosis virus-1 genomic RNA, Journal of Virology, Vol: 93, Pages: 1-18, ISSN: 1098-5514
Satellite tobacco necrosis virus-1 (STNV-1) is a model system for in vitro RNA encapsidation studies (Patel et al., PNAS 2015, 2017), leading to the identification of degenerate packaging signals (PSs) proposed to be involved in the recognition of its genome by the capsid protein (CP). The aim of the present work was to investigate whether these putative PSs can confer selective packaging of STNV-1 RNA in vivo and assess the prospects of using decoy RNAs in antiviral therapy. We have developed an in planta packaging assay based on the transient expression of STNV-1 CP and assessed the ability of the resulting VLPs to encapsidate mutant STNV-1 RNAs expected to have different encapsidation potential based on in vitro studies. The results revealed that >90% of the encapsidated RNAs are host-derived, although there is some selectivity of packaging for STNV-1 RNA and certain host RNAs. Comparison of the packaging efficiency of mutant STNV-1 RNAs showed that they are encapsidated mainly according to their abundance within the cells, rather than the presence or absence of the putative PSs previously identified from in vitro studies. By contrast, subsequent infection experiments demonstrated that host RNAs represent only <1% of virion content. Although selective encapsidation of certain host RNAs was noted, no direct correlation could be made between this preference and the presence of potential PSs in the host RNA sequences. Overall the data illustrate the differences in RNA packaging efficiency identified through in vitro studies are insufficient to explain the specific packaging of STNV-1 RNA.
Kotta-Loizou I, 2019, Mycoviruses: past, present, and future, Viruses, Vol: 11, ISSN: 1999-4915
Shah UA, Kotta-Loizou I, Fitt BDL, et al., 2019, Identification, molecular characterization, and biology of a novel quadrivirus infecting the phytopathogenic fungus Leptosphaeria biglobosa, Viruses, Vol: 11, ISSN: 1999-4915
Here we report the molecular characterisation of a novel dsRNA virus isolated from the filamentous, plant pathogenic fungus Leptosphaeria biglobosa and known to cause significant alterations to fungal pigmentation and growth and to result in hypervirulence, as illustrated by comparisons between virus-infected and -cured isogenic fungal strains. The virus forms isometric particles approximately 40–45 nm in diameter and has a quadripartite dsRNA genome structure with size ranges of 4.9 to 4 kbp, each possessing a single ORF. Sequence analysis of the putative proteins encoded by dsRNAs 1–4, termed P1–P4, respectively, revealed modest similarities to the amino acid sequences of equivalent proteins predicted from the nucleotide sequences of known and suspected members of the family Quadriviridae and for that reason the virus was nominated Leptosphaeria biglobosa quadrivirus-1 (LbQV-1). Sequence and phylogenetic analysis using the P3 sequence, which encodes an RdRP, revealed that LbQV-1 was most closely related to known and suspected quadriviruses and monopartite totiviruses rather than other quadripartite mycoviruses including chrysoviruses and alternaviruses. Of the remaining encoded proteins, LbQV-1 P2 and P4 are structural proteins but the function of P1 is unknown. We propose that LbQV-1 is a novel member of the family Quadriviridae.
Filippou C, Garrido-Jurado I, Meyling NV, et al., 2018, Mycoviral population dynamics in Spanish isolates of the entomopathogenic fungus Beauveria bassiana, Viruses, Vol: 10, ISSN: 1999-4915
The use of mycoviruses to manipulate the virulence of entomopathogenic fungi employed as biocontrol agents may lead to the development of novel methods to control attacks by insect pests. Such approaches are urgently required, as existing agrochemicals are being withdrawn from the market due to environmental and health concerns. The aim of this work is to investigate the presence and diversity of mycoviruses in large panels of entomopathogenic fungi, mostly from Spain and Denmark. In total, 151 isolates belonging to the genera Beauveria, Metarhizium, Lecanicillium, Purpureocillium, Isaria, and Paecilomyces were screened for the presence of dsRNA elements and 12 Spanish B. bassiana isolates were found to harbor mycoviruses. All identified mycoviruses belong to three previously characterised species, the officially recognised Beauveria bassiana victorivirus 1 (BbVV-1) and the proposed Beauveria bassiana partitivirus 2 (BbPV-2) and Beauveria bassiana polymycovirus 1 (BbPmV-1); individual B. bassiana isolates may harbor up to three of these mycoviruses. Notably, these mycovirus species are under distinct selection pressures, while recombination of viral genomes increases population diversity. Phylogenetic analysis of the RNA-dependent RNA polymerase gene sequences revealed that the current population structure in Spain is potentially a result of both vertical and horizontal mycovirus transmission. Finally, pathogenicity experiments using the Mediterranean fruit fly Ceratitis capitata showed no direct correlation between the presence of any particular mycovirus and the virulence of the B. bassiana isolates, but illustrated potentially interesting isolates that exhibit relatively high virulence, which will be used in more detailed virulence experimentation in the future.
Giaginis C, Sampani A, Kotta-Loizou I, et al., 2018, Elevated Hu-antigen Receptor (HuR) expression is associated with tumor aggressiveness and poor prognosis but not with COX-2 expression in invasive breast carcinoma patients, Pathology and Oncology Research, Vol: 24, Pages: 631-640, ISSN: 1219-4956
Hu-antigen R (HuR), a RNA-binding protein, is considered to play a crucial role in tumor development and progression by stabilizing or regulating a group of cellular mRNAs of cancer-related genes, such as cyclooxygenase-2 (COX-2). The present study aimed to evaluate the clinical significance of HuR and COX-2 expression in invasive breast carcinoma. HuR and COX-2 protein expression was assessed immunohistochemically on paraffin-embedded breast cancer tissue sections obtained from 121 patients and was statistically analyzed with clinicopathological parameters, estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), as well as with tumor cells' proliferative capacity and overall and disease-free patients' survival. High HuR expression was positively associated with larger tumor size and advanced disease stage (p = 0.0234 and p = 0.0361, respectively), being more frequently observed in ER negative cases (p = 0.0208). High COX-2 expression was negatively associated with histological (p < 0.0001) and nuclear (p = 0.0033) grade and tumor cells' proliferative rate (p = 0.0015), being more frequently observed in luminal-A compared to other molecular subtypes (p = 0.0221). High HuR expression was associated with poor overall and disease-free patients' survival at both univariate (log-rank test, p = 0.0092 and p = 0.0004, respectively) and multivariate (Cox-regression analysis, p = 0.0223 and p = 0.0004, respectively) level. On the other hand, high COX-2 expression was associated with favorable overall and disease-free patients' survival merely at univariate level (log-rank test, p = 0.0389 and p = 0.0154, respectively). HuR expression was not associated with COX-2 expression (Spearman R = 0.1489, p = 0.1032). The present data support evidence that HuR is associated with tumor ag
Glyde R, Ye F, Jovanovic M, et al., 2018, Structures of bacterial RNA polymerase complexes reveal mechanisms of DNA loading and transcription initiation, Molecular Cell, Vol: 70, Pages: 1111-1120.e3, ISSN: 1097-2765
Gene transcription is carried out by multi-subunit RNA polymerases (RNAP).Transcription initiation is a dynamic multi-step process that involves the opening of the double stranded DNA to form a transcription bubble and delivery of the template strand deep into the RNAP for RNA synthesis. Applying cryo electron microscopy to a unique transcription system using 54 (N), the major bacterial variant sigma factor, we capture a new intermediate state at 4.1 Å where promoter DNA is caught at the entrance of the RNAP cleft. Combining with new structures of the open promotercomplex and an initial de novo transcribing complex at 3.4 and 3.7 Å respectively, our studies reveal the dynamics of DNA loading and mechanism of transcription bubble stabilisation that involves coordinated, large scale conformational changes of the universally conserved features within RNAP and DNA. In addition, our studies reveal a novel mechanism of strand separation by 54.
Levidou G, Kotta-Loizou I, Tasoulas J, et al., 2018, Clinical Significance and Biological Role of HuR in Head and Neck Carcinomas, DISEASE MARKERS, Vol: 2018, ISSN: 0278-0240
Background. Hu-antigen R (HuR) is a posttranscriptional regulator of several target mRNAs, implicated in carcinogenesis. This review aims to present the current evidence regarding the biological role and potential clinical significance of HuR in head and neck carcinomas. Methods. The existing literature concerning HuR expression and function in head and neck carcinomas is critically presented and summarised. Results. HuR is expressed in the majority of the examined samples, showing higher cytoplasmic levels in malignant or premalignant cases. Moreover, HuR modulates several genes implicated in biological processes important for malignant transformation, growth, and invasiveness. HuR seems to be an adverse prognosticator in patients with OSCCs, whereas a correlation with a more aggressive phenotype is reported in several types of carcinomas. Conclusions. A consistent role of HuR in the carcinogenesis and progression of head and neck carcinomas is suggested; nevertheless, further studies are warranted to expand the present information.
Kotta-Loizou I, Coutts RHA, 2017, Mycoviruses in Aspergilli: a comprehensive review, Frontiers in Microbiology, Vol: 8, ISSN: 1664-302X
Fungi, similar to all species, are susceptible to viral infection. Aspergillus is arguably the most well studied fungal genus because of its medical, ecological and economical significance. Mycoviruses were initially detected in Aspergillus species almost 50 years ago and the field continues to be active today with ground-breaking discoveries. The aim of the present review is to cover the scientific progress in all aspects of mycovirology as exemplified by Aspergillus-focused research. Initially an overview of the population studies illustrating the presence of mycoviruses in numerous important Aspergillus species, such as A. niger, A. flavus, and A. fumigatus with be presented. Moreover the intricacies of mycovirus transmission, both inter- and intra-species, will be discussed together with the methodologies used to investigate viral dispersion in a laboratory setting. Subsequently, the genomic features of all molecularly characterized mycoviruses to date will be analyzed in depth. These include members of established viral families, such as Partitiviridae, Chrysoviridae and Totiviridae, but also more recent, novel discoveries that led to the proposal of new viral families, such as Polymycoviridae, Alternaviridae and, in the context of the present review, Exartaviridae. Finally, the major issue of phenotypic effects of mycoviral infection on the host is addressed, including aflatoxin production in A. flavus, together with growth and virulence in A. fumigatus. Although the molecular mechanisms behind these phenomena are yet to be elucidated, recent studies suggest that by implication, RNA silencing may be involved.
Jovanovic M, Waite C, James E, et al., 2017, Functional Characterization of Key Residues in Regulatory Proteins HrpG and HrpV of Pseudomonas syringae pv. tomato DC3000, Molecular Plant-Microbe Interactions, Vol: 30, Pages: 656-665, ISSN: 0894-0282
The plant pathogen Pseudomonas syringae pv. tomato DC3000 uses a type III secretion system (T3SS) to transfer effector proteins into the host. The expression of T3SS proteins is controlled by the HrpL σ factor. Transcription of hrpL is σ54-dependent and bacterial enhancer-binding proteins HrpR and HrpS coactivate the hrpL promoter. The HrpV protein imposes negative control upon HrpR and HrpS through direct interaction with HrpS. HrpG interacts with HrpV and relieves such negative control. The sequence alignments across Hrp group I-type plant pathogens revealed conserved HrpV and HrpG amino acids. To establish structure–function relationships in HrpV and HrpG, either truncated or alanine substitution mutants were constructed. Key functional residues in HrpV and HrpG are found within their C-terminal regions. In HrpG, L101 and L105 are indispensable for the ability of HrpG to directly interact with HrpV and suppress HrpV-dependent negative regulation of HrpR and HrpS. In HrpV, L108 and G110 are major determinants for interactions with HrpS and HrpG. We propose that mutually exclusive binding of HrpS and HrpG to the same binding site of HrpV governs a transition from negative control to activation of the HrpRS complex leading to HrpL expression and pathogenicity of P. syringae.
Theocharis S, Kotta-Loizou I, Giaginis C, et al., 2017, Expression and clinical significance of concomitant FAK/Src and p-paxillin in mobile tongue squamous cell carcinoma, Anticancer Research, ISSN: 0250-7005
Background/Aim: The focal adhesion kinase (FAK)/SRC phosphorylation cascade and its downstream target paxillin have been implicated in malignant transformation, tumor growth and progression, together with metastasis. The present study aimed to evaluate the clinical significance of concomitant FAK/SRC and p-paxillin expression in mobile tongue squamous cell carcinoma (SCC). Materials and Methods: FAK, SRC and phospho-paxillin expression in 48 mobile tongue SCC tissue samples was assessed immunohistochemically and analyzed with respect to clinicopathological characteristics and patient survival. Results: Concomitant high FAK/SRC expression was significantly associated with high grade of tumor differentiation (p=0.048) and longer disease-free patient survival (log-rank test, p=0.019). High p-paxillin expression was significantly associated with greater depth of invasion (p=0.002), lymph node metastasis (p=0.048) and poorer disease-free patient survival (log-rank test, p=0.021; Cox-regression analysis, p=0.031). Conclusion: The present study provides evidence that FAK/SRC and paxillin play a role in the pathophysiological aspects of mobile tongue SCC and could constitute therapeutic targets.
Kotta-Loizou I, Coutts RHA, 2017, Studies on the virome of the entomopathogenic fungus Beauveria bassiana reveal novel dsRNA elements and mild hypervirulence, PLOS Pathogens, Vol: 13, ISSN: 1553-7366
The entomopathogenic fungus Beauveria bassiana has a wide host range and is used as a biocontrol agent against arthropod pests. Mycoviruses have been described in phytopathogenic fungi while in entomopathogenic fungi their presence has been reported only rarely. Here we show that 21.3% of a collection of B. bassiana isolates sourced from worldwide locations, harbor dsRNA elements. Molecular characterization of these elements revealed the prevalence of mycoviruses belonging to the Partitiviridae and Totiviridae families, the smallest reported virus to date, belonging to the family Narnaviridae, and viruses unassigned to a family or genus. Of particular importance is the discovery of members of a newly proposed family Polymycoviridae in B. bassiana. Polymycoviruses, previously designated as tetramycoviruses, consist of four non-conventionally encapsidated capped dsRNAs. The presence of additional non-homologous genomic segments in B. bassiana polymycoviruses and other fungi illustrates the unprecedented dynamic nature of the viral genome. Finally, a comparison of virus-free and virus-infected isogenic lines derived from an exemplar B. bassiana isolate revealed a mild hypervirulent effect of mycoviruses on the growth of their host isolate and on its pathogenicity against the greater wax moth Galleria mellonella, highlighting for the first time the potential of mycoviruses as enhancers of biocontrol agents.
Kotta-Loizou I, Vasilopoulos SN, Coutts RHA, et al., 2016, Current evidence and future perspectives on HuR and breast cancer development, prognosis and treatment, Neoplasia, Vol: 18, Pages: 674-688, ISSN: 1522-8002
Hu-antigen R (HuR) is an RNA-binding post-transcriptional regulator that belongs to the Hu/ELAVfamily. HuR expression levels are modulated by a variety of proteins, microRNAs, chemicalcompounds or the microenvironment and in turn HuR affects mRNA stability and translation ofvarious genes implicated in breast cancer formation, progression, metastasis and treatment. The aimof the present review is to critically summarise the role of HuR in breast cancer development and itspotential as a prognosticator and a therapeutic target. In this aspect, all the existing Englishliterature concerning HuR expression and function in breast cancer cell lines, in vivo animal modelsand clinical studies is critically presented and summarized. HuR modulates many genes implicated inbiological processes crucial for breast cancer formation, growth and metastasis, while the linkbetween HuR and these processes has been demonstrated directly in vitro and in vivo. Additionally,clinical studies reveal that HuR is associated with more aggressive forms of breast cancer and is aputative prognosticator for patients’ survival. All the above indicate HuR as a promising drug targetfor cancer therapy; nevertheless, additional studies are required to fully understand its potential anddetermine against which types of breast cancer and at which stage of the disease a therapeuticagent targeting HuR would be more effective.
Engl C, Schafer J, Kotta-Loizou I, et al., 2016, Cellular and molecular phenotypes depending upon the RNA repair system RtcAB of Escherichia coli, Nucleic Acids Research, Vol: 44, Pages: 9933-9941, ISSN: 1362-4962
RNA ligases function pervasively across the three kingdoms of life for RNA repair, splicing and can be stress induced. The RtcB protein (also HSPC117, C22orf28, FAAP and D10Wsu52e) is one such conserved ligase, involved in tRNA and mRNA splicing. However, its physiological role is poorly described, especially in bacteria. We now show in Escherichia coli bacteria that the RtcR activated rtcAB genes function for ribosome homeostasis involving rRNA stability. Expression of rtcAB is activated by agents and genetic lesions which impair the translation apparatus or may cause oxidative damage in the cell. Rtc helps the cell to survive challenges to the translation apparatus, including ribosome targeting antibiotics. Further, loss of Rtc causes profound changes in chemotaxis and motility. Together, our data suggest that the Rtc system is part of a previously unrecognized adaptive response linking ribosome homeostasis with basic cell physiology and behaviour.
Schafer J, Jovanovic G, Kotta-Loizou I, et al., 2016, A data comparison between a traditional and the single-step β-galactosidase assay, Data in Brief, Vol: 8, Pages: 350-352, ISSN: 2352-3409
This article describes reproducibility of a single-step automated β-galactosidase, and the equivalence of its data to the traditional assay ("Experiments in Molecular Genetics" [1]). This was done via a pairwise comparison of both methods using strains with Miller Unit [MU] values ranging from 0 to over 2000. The data presented in this article is associated with the research article entitled "A single-step method for mid to high throughput β-galactosidase assays in Escherichia coli using a microplate reader" [2].
Schafer J, Jovanovic G, Kotta-Loizou I, et al., 2016, Single-step method for β-galactosidase assays in Escherichia coli using a 96-well microplate reader, Analytical Biochemistry, Vol: 503, Pages: 56-57, ISSN: 1096-0309
Historically, the lacZ gene is one of the most universally used reporters of gene expression in molecular biology. Its activity can be quantified using an artificial substrate, o-nitrophenyl-ß-d-galactopyranoside (ONPG). However, the traditional method for measuring LacZ activity (first described by J. H. Miller in 1972) can be challenging for a large number of samples, is prone to variability, and involves hazardous compounds for lysis (e.g., chloroform, toluene). Here we describe a single-step assay using a 96-well microplate reader with a proven alternative cell permeabilization method. This modified protocol reduces handling time by 90%.
Kanhayuwa L, Kotta-Loizou I, Oezkan S, et al., 2015, A novel mycovirus from Aspergillus fumigatus contains four unique dsRNAs as its genome and is infectious as dsRNA, Proceedings of the National Academy of Sciences of the United States of America, Vol: 112, Pages: 9100-9105, ISSN: 0027-8424
We report the discovery and characterization of a double-stranded RNA (dsRNA) mycovirus isolated from the human pathogenic fungus Aspergillus fumigatus, Aspergillus fumigatus tetramycovirus-1 (AfuTmV-1), which reveals several unique features not found previously in positive-strand RNA viruses, including the fact that it represents the first dsRNA (to our knowledge) that is not only infectious as a purified entity but also as a naked dsRNA. The AfuTmV-1 genome consists of four capped dsRNAs, the largest of which encodes an RNA-dependent RNA polymerase (RdRP) containing a unique GDNQ motif normally characteristic of negative-strand RNA viruses. The third largest dsRNA encodes an S-adenosyl methionine–dependent methyltransferase capping enzyme and the smallest dsRNA a P-A-S–rich protein that apparently coats but does not encapsidate the viral genome as visualized by atomic force microscopy. A combination of a capping enzyme with a picorna-like RdRP in the AfuTmV-1 genome is a striking case of chimerism and the first example (to our knowledge) of such a phenomenon. AfuTmV-1 appears to be intermediate between dsRNA and positive-strand ssRNA viruses, as well as between encapsidated and capsidless RNA viruses.
Kotta-Loizou I, Karakasiliotis I, Vassilaki N, et al., 2015, Expression of the Novel Hepatitis C Virus Core+1/ARF Protein in the Context of JFH1-Based Replicons, JOURNAL OF VIROLOGY, Vol: 89, Pages: 5164-5170, ISSN: 0022-538X
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Kotta-Loizou I, Sipkova J, Coutts RHA, 2015, Identification and sequence determination of a novel double-stranded RNA mycovirus from the entomopathogenic fungus <i>Beauveria bassiana</i>, ARCHIVES OF VIROLOGY, Vol: 160, Pages: 873-875, ISSN: 0304-8608
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- Citations: 31
Shah UA, Kotta-Loizou I, Coutts RHA, 2015, Sequence determination of a satellite RNA isolated from <i>Aspergillus foetidus</i>, ARCHIVES OF VIROLOGY, Vol: 160, Pages: 883-885, ISSN: 0304-8608
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- Citations: 5
Kotta-Loizou I, Giaginis C, Theocharis S, 2014, Clinical significance of HuR expression in human malignancy, MEDICAL ONCOLOGY, Vol: 31, ISSN: 1357-0560
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- Citations: 61
Theocharis S, Giaginis C, Klijanienko J, et al., 2014, Concomitant elevated FAK and Src expression is associated with high histopathological grade and favourable disease-free patients' survival in mobile tongue Squamous Cell Carcinoma (SCC), Publisher: SPRINGER, Pages: S33-S33, ISSN: 0945-6317
Theocharis S, Kotta-Loizou I, Klijanienko J, et al., 2014, Extracellular signal-regulated kinase (ERK) expression and activation in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patients survival, TUMOR BIOLOGY, Vol: 35, Pages: 6455-6465, ISSN: 1010-4283
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- Citations: 15
Kotta-Loizou I, 2014, Evolutionary and functional studies on the novel Hepatitis C virus core+1/ARF protein, 2nd International Work-Conference on Bioinformatics and Biomedical Engineering (IWBBIO), Publisher: COPICENTRO GRANADA S L, Pages: 204-204
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