Publications
243 results found
Tabib-Salazar A, Mulvenna N, Severinov K, et al., 2019, Xenogeneic regulation of the bacterial transcription machinery, Journal of Molecular Biology, Vol: 431, Pages: 4078-4092, ISSN: 0022-2836
The parasitic life cycle of viruses involves the obligatory subversion of the host's macromolecular processes for efficient viral progeny production. Viruses that infect bacteria, bacteriophages (phages), are no exception and have evolved sophisticated ways to control essential biosynthetic machineries of their bacterial prey to benefit phage development. The xenogeneic regulation of bacterial cell function is a poorly understood area of bacteriology. The activity of the bacterial transcription machinery, the RNA polymerase (RNAP), is often regulated by a variety of mechanisms involving small phage-encoded proteins. In this review, we provide a brief overview of known phage proteins that interact with the bacterial RNAP and compare how two prototypical phages of Escherichia coli, T4 and T7, use small proteins to 'puppeteer' the bacterial RNAP to ensure a successful infection.
Berry J, Gurung I, Anonsen JH, et al., 2019, Global biochemical and structural analysis of the type IV pilus from the Gram-positive bacterium Streptococcus sanguinis, Journal of Biological Chemistry, Vol: 294, Pages: 6796-6808, ISSN: 0021-9258
Type IV pili (Tfp) are functionally versatile filaments, widespread in prokaryotes, that belong to a large class of filamentous nanomachines known as type IV filaments (Tff). Although Tfp have been extensively studied in several Gram-negative pathogens where they function as key virulence factors, many aspects of their biology remain poorly understood. Here, we performed a global biochemical and structural analysis of Tfp in a recently emerged Gram-positive model, Streptococcus sanguinis. In particular, we focused on the five pilins and pilin-like proteins involved in Tfp biology in S. sanguinis. We found that the two major pilins, PilE1 and PilE2, (i) follow widely conserved principles for processing by the prepilin peptidase PilD and for assembly into filaments; (ii) display only one of the post-translational modifications frequently found in pilins, i.e. a methylated N-terminus; (iii) are found in the same hetero-polymeric filaments; and (iv) are not functionally equivalent. The 3D structure of PilE1, solved by NMR, revealed a classical pilin fold with a highly unusual flexible C-terminus. Intriguingly, PilE1 more closely resembles pseudopilins forming shorter Tff than bona fide Tfp-forming major pilins, underlining the evolutionary relatedness among different Tff. Finally, we show that S. sanguinis Tfp contain a low abundance of three additional proteins processed by PilD, the minor pilins PilA, PilB, and PilC. These findings provide the first global biochemical and structural picture of a Gram-positive Tfp and have fundamental implications for our understanding of a widespread class of filamentous nanomachines.
Zhang P, Wang Z, Zhao S, et al., 2019, <SUP>1</SUP>H, <SUP>13</SUP>C and <SUP>15</SUP>N NMR assignments of Bacillus subtilis bacteriophage SPO1 protein Gp46, BIOMOLECULAR NMR ASSIGNMENTS, Vol: 13, Pages: 245-247, ISSN: 1874-2718
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- Citations: 3
Miliara X, Tatsuta T, Berry J-L, et al., 2019, Structural determinants of lipid specificity within Ups/PRELI lipid transfer proteins, Nature Communications, Vol: 10, Pages: 1-15, ISSN: 2041-1723
Conserved lipid transfer proteins of the Ups/PRELI family regulate lipid accumulation in mitochondria by shuttling phospholipids in a lipid-specific manner across the intermembrane space. Here, we combine structural analysis, unbiased genetic approaches in yeast and molecular dynamics simulations to unravel determinants of lipid specificity within the conserved Ups/PRELI family. We present structures of human PRELID1–TRIAP1 and PRELID3b–TRIAP1 complexes, which exert lipid transfer activity for phosphatidic acid and phosphatidylserine, respectively. Reverse yeast genetic screens identify critical amino acid exchanges that broaden and swap their lipid specificities. We find that amino acids involved in head group recognition and the hydrophobicity of flexible loops regulate lipid entry into the binding cavity. Molecular dynamics simulations reveal different membrane orientations of PRELID1 and PRELID3b during the stepwise release of lipids. Our experiments thus define the structural determinants of lipid specificity and the dynamics of lipid interactions by Ups/PRELI proteins.
Polo LM, Xu Y, Hornyak P, et al., 2019, Efficient single-strand break repair requires binding to both poly(ADP-Ribose) and DNA by the central BRCT domain of XRCC1, Cell Reports, Vol: 26, Pages: 573-581.e5, ISSN: 2211-1247
XRCC1 accelerates repair of DNA single-strand breaks by acting as a scaffold protein for the recruitment of Polβ, LigIIIα, and end-processing factors, such as PNKP and APTX. XRCC1 itself is recruited to DNA damage through interaction of its central BRCT domain with poly(ADP-ribose) chains generated by PARP1 or PARP2. XRCC1 is believed to interact directly with DNA at sites of damage, but the molecular basis for this interaction within XRCC1 remains unclear. We now show that the central BRCT domain simultaneously mediates interaction of XRCC1 with poly(ADP-ribose) and DNA, through separate and non-overlapping binding sites on opposite faces of the domain. Mutation of residues within the DNA binding site, which includes the site of a common disease-associated human polymorphism, affects DNA binding of this XRCC1 domain in vitro and impairs XRCC1 recruitment and retention at DNA damage and repair of single-strand breaks in vivo.
Andreasen M, Meisl G, Taylor JD, et al., 2019, Physical determinants of amyloid assembly in biofilm formation, mBio, Vol: 10, ISSN: 2150-7511
A wide range of bacterial pathogens have been shown to form biofilms, which significantly increase their resistance to environmental stresses, such as antibiotics, and are thus of central importance in the context of bacterial diseases. One of the major structural components of these bacterial biofilms are amyloid fibrils, yet the mechanism of fibril assembly and its importance for biofilm formation are currently not fully understood. By studying fibril formation in vitro, in a model system of two common but unrelated biofilm-forming proteins, FapC from Pseudomonas fluorescens and CsgA from Escherichia coli, we found that the two proteins have a common aggregation mechanism. In both systems, fibril formation proceeds via nucleated growth of linear fibrils exhibiting similar measured rates of elongation, with negligible fibril self-replication. These similarities between two unrelated systems suggest that convergent evolution plays a key role in tuning the assembly kinetics of functional amyloid fibrils and indicates that only a narrow window of mechanisms and assembly rates allows for successful biofilm formation. Thus, the amyloid assembly reaction is likely to represent a means for controlling biofilm formation, both by the organism and by possible inhibitory drugs.IMPORTANCE Biofilms are generated by bacteria, embedded in the formed extracellular matrix. The biofilm's function is to improve the survival of a bacterial colony through, for example, increased resistance to antibiotics or other environmental stresses. Proteins secreted by the bacteria act as a major structural component of this extracellular matrix, as they self-assemble into highly stable amyloid fibrils, making the biofilm very difficult to degrade by physical and chemical means once formed. By studying the self-assembly mechanism of the fibrils from their monomeric precursors in two unrelated bacteria, our experimental and theoretical approaches shed light on the mechanism of functional amyloid as
Chorev DS, Baker LA, Wu D, et al., 2018, Protein assemblies ejected directly from native membranes yield complexes for mass spectrometry, SCIENCE, Vol: 362, Pages: 829-+, ISSN: 0036-8075
Pakharukova N, McKenna S, Tuittila M, et al., 2018, Archaic and alternative chaperones preserve pilin folding energy by providing incomplete structural information, JOURNAL OF BIOLOGICAL CHEMISTRY, Vol: 293, Pages: 17070-17080, ISSN: 0021-9258
Rouse SL, Matthews SJ, Dueholm MS, 2018, Ecology and biogenesis of functional amyloids in pseudomonas, Journal of Molecular Biology, Vol: 430, Pages: 3685-3695, ISSN: 0022-2836
Functional amyloids can be found in the extracellular matrix produced by many bacteria during biofilm growth. They mediate the initial attachment of bacteria to surfaces and provide stability and functionality to mature biofilms. Efficient amyloid biogenesis requires a highly coordinated system of amyloid subunits, molecular chaperones and transport systems. The functional amyloid of Pseudomonas (Fap) represents such a system. Here, we review the phylogenetic diversification of the Fap system, its potential ecological role and the dedicated machinery required for Fap biogenesis, with a particular focus on the amyloid exporter FapF, the structure of which has been recently resolved. We also present a sequence covariance-based in silico model of the FapC fiber-forming subunit. Finally, we highlight key questions that remain unanswered and we believe deserve further attention by the scientific community.
Darvill N, Blake T, Rouse S, et al., 2018, Structural basis of phosphatidic acid sensing by APH in apicomplexan parasites, Structure, Vol: 26, Pages: 1059-1071.e6, ISSN: 0969-2126
Plasmodium falciparum and Toxoplasma gondii are obligate intracellular parasites that belong to the phylum of Apicomplexa and cause major human diseases. Their access to an intracellular lifestyle is reliant on the coordinated release of proteins from the specialized apical organelles called micronemes and rhoptries. A specific phosphatidic acid effector, the acylated pleckstrin homology domain-containing protein (APH) plays a central role in microneme exocytosis and thus is essential for motility, cell entry, and egress. TgAPH is acylated on the surface of the micronemes and recruited to phosphatidic acid (PA)-enriched membranes. Here, we dissect the atomic details of APH PA-sensing hub and its functional interaction with phospholipid membranes. We unravel the key determinant of PA recognition for the first time and show that APH inserts into and clusters multiple phosphate head-groups at the bilayer binding surface.
Rouse S, Stylianou F, wu G, et al., 2018, The FapF amyloid secretion transporter possesses an atypical asymmetric coiled coil, Journal of Molecular Biology, Vol: 430, Pages: 3863-3871, ISSN: 0022-2836
Gram-negative bacteria possess specialized biogenesis machineries that facilitate the export of amyloid subunits, the fibers of which are key components of their biofilm matrix. The secretion of bacterial functional amyloid requires a specialized outer-membrane protein channel through which unfolded amyloid substrates are translocated. We previously reported the crystal structure of the membrane-spanning domain of the amyloid subunit transporter FapF from Pseudomonas. However, the structure of the periplasmic domain, which is essential for amyloid transport, is yet to be determined. Here, we present the crystal structure of the N-terminal periplasmic domain at 1.8-Å resolution. This domain forms a novel asymmetric trimeric coiled coil that possesses a single buried tyrosine residue as well as an extensive hydrogen-bonding network within a glutamine layer. This new structural insight allows us to understand this newly described functional amyloid secretion system in greater detail.
Liu B, Wang Z, Lan L, et al., 2018, A rapid colorimetric method to visualize protein interactions, Chemistry - A European Journal, Vol: 24, Pages: 6727-6731, ISSN: 0947-6539
As key molecules in most biological pathways, proteins physically contact one or more biomolecules in a highly specific manner. Several driving forces (i.e., electrostatic and hydrophobic) facilitate such interactions and a variety of methods have been developed to monitor these processes both in vivo and in vitro. In this work, a new method is reported for the detection of protein interactions by visualizing a color change of a cyanine compound, a supramolecule complex of 3,3-di-(3-sulfopropyl)-4,5,4',5'-dibenzo-9-methyl-thiacarbocyanine triethylammonium salt (MTC). Nuclear magnetic resonance (NMR) studies suggest that the hydrophobic nature of the protein surfaces drives MTC into different types of aggregates with distinct colors. When proteins interact with other biomolecules, the hydrophobic surface of the complex differs, resulting in a shift in the form of MTC aggregation, which results in a color change. As a result, this in vitro method has the potential to become a rapid tool for the confirmation of protein-biomolecule interactions, without the requirements for sophisticated instrumentation or approaches.
Tabib-Salazar A, Liu B, Declan B, et al., 2018, T7 phage factor required for managing RpoS in Escherichia coli, Proceedings of the National Academy of Sciences, Vol: 115, Pages: E5353-E5362, ISSN: 0027-8424
T7 development in Escherichia coli requires the inhibition of the housekeepingform of the bacterial RNA polymerase (RNAP), Eσ70, by two T7 proteins: Gp2and Gp5.7. While the biological role of Gp2 is well understood, that of Gp5.7remains to be fully deciphered. Here, we present results from functional andstructural analyses to reveal that Gp5.7 primarily serves to inhibit EσS, thepredominant form of the RNAP in the stationary phase of growth, whichaccumulates in exponentially growing E. coli as a consequence of buildup ofguanosine pentaphosphate ((p)ppGpp) during T7 development. We furtherdemonstrate a requirement of Gp5.7 for T7 development in E. coli cells in thestationary phase of growth. Our finding represents a paradigm for how somelytic phages have evolved distinct mechanisms to inhibit the bacterialtranscription machinery to facilitate phage development in bacteria in theexponential and stationary phases of growth.
Gatta AT, Sauerwein AC, Zhuravleva A, et al., 2018, Structural insights into a StART-like domain in Lam4 and its interaction with sterol ligands, BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, Vol: 495, Pages: 2270-2274, ISSN: 0006-291X
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- Citations: 11
rouse S, hawthorne, berry, et al., 2017, A new class of hybrid secretion system is employed in Pseudomonas amyloid biogenesis, Nature Communications, Vol: 8, ISSN: 2041-1723
Gram-negative bacteria possess specialised biogenesis machineries that facilitate the export of amyloid subunits for construction of a biofilm matrix. The secretion of bacterial functional amyloid requires a bespoke outer-membrane protein channel through which unfolded amyloid substrates are translocated. Here, we combine X-ray crystallography, native mass spectrometry, single-channel electrical recording, molecular simulations and circular dichroism measurements to provide high-resolution structural insight into the functional amyloid transporter from Pseudomonas, FapF. FapF forms a trimer of gated β-barrel channels in which opening is regulated by a helical plug connected to an extended coil-coiled platform spanning the bacterial periplasm. Although FapF represents a unique type of secretion system, it shares mechanistic features with a diverse range of peptide translocation systems. Our findings highlight alternative strategies for handling and export of amyloid protein sequences.
Otzen DE, Vad BS, Dueholm MS, et al., 2017, Self-organizing amyloid in bacteria, 19th IUPAB Congress / 11th EBSA Congress, Publisher: SPRINGER, Pages: S341-S341, ISSN: 0175-7571
Otzen DE, Vad BS, Dueholm MS, et al., 2017, Self-organizing amyloid in bacteria, 19th IUPAB Congress / 11th EBSA Congress, Publisher: SPRINGER, Pages: S98-S98, ISSN: 0175-7571
Tabib-Salazar A, Liu B, Shadrin A, et al., 2017, Full shut-off of Escherichia coli RNA-polymerase by T7 phage requires a small phage-encoded DNA-binding protein, Nucleic Acids Research, Vol: 45, Pages: 7697-7707, ISSN: 1362-4962
Infection of Escherichia coli by the T7 phage leads to rapid and selective inhibition of the bacterial RNA polymerase (RNAP) by the 7 kDa T7 protein Gp2. We describe the identification and functional and structural characterisation of a novel 7 kDa T7 protein, Gp5.7, which adopts a winged helix-turn-helix-like structure and specifically represses transcription initiation from host RNAP-dependent promoters on the phage genome via a mechanism that involves interaction with DNA and the bacterial RNAP. Whereas Gp2 is indispensable for T7 growth in E. coli, we show that Gp5.7 is required for optimal infection outcome. Our findings provide novel insights into how phages fine-tune the activity of the host transcription machinery to ensure both successful and efficient phage progeny development.
Jia Y, Benjamin S, Liu Q, et al., 2017, "Toxoplasma gondii immune mapped protein 1 is anchored to the inner leaflet of the plasma membrane and adopts a novel protein fold" (vol 1865, pg 208, 2017), BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS, Vol: 1865, Pages: 631-631, ISSN: 1570-9639
Wang S, Lin Y, Todorova N, et al., 2017, Facet-dependent interactions of islet amyloid polypeptide with gold nanoparti-cles: implications for fibril formation and peptide-induced lipid membrane dis-ruption, Chemistry of Materials, Vol: 29, ISSN: 1520-5002
A comprehensive understanding of the mechanisms of interaction between proteins or peptides and nanomaterials is crucial for the development of nanomaterial-based diagnos-tics and therapeutics. In this work, we systematically explored the interactions between citrate-capped gold nanoparticles (AuNPs) and islet amyloid polypeptide (IAPP), a 37-amino acid peptide hormone co-secreted with insulin from the pancreatic islet. We uti-lized diffusion-ordered spectroscopy, isothermal titration calorimetry, localized surface plasmon resonance spectroscopy, gel electrophoresis, atomic force microscopy, transmis-sion electron microscopy (TEM), and molecular dynamics (MD) simulations to systemati-cally elucidate the underlying mechanism of the IAPP−AuNP interactions. Because of the presence of a metal-binding sequence motif in the hydrophilic peptide domain, IAPP strongly interacts with the Au surface in both the monomeric and fibrillar states. Circular dichroism showed that AuNPs triggered the IAPP conformational transition from random coil to ordered structures (α-helix and β-sheet), and TEM imaging suggested the accelera-tion of IAPP fibrillation in the presence of AuNPs. MD simulations revealed that the IAPP−AuNP interactions were initiated by the N-terminal domain (IAPP residues 1−19), which subsequently induced a facet-dependent conformational change in IAPP. On a Au(111) surface, IAPP was unfolded and adsorbed directly onto the Au surface, while for the Au(100) surface, it interacted predominantly with the citrate adlayer and retained some helical conformation. The observed affinity of AuNPs for IAPP was further applied to reduce the level of peptide-induced lipid membrane disruption.
Rouse SL, Hawthorne W, Berry J, et al., 2017, Structural and Mechanistic Insights into Transport of Functional Amyloid Subunits across the Pseudomonas Outer Membrane, 61st Annual Meeting of the Biophysical-Society, Publisher: CELL PRESS, Pages: 188A-188A, ISSN: 0006-3495
Jønsson R, Liu B, Struve C, et al., 2016, Structural and functional studies of Escherichia coli Aggregative Adherence Fimbriae (AAF/V) reveal a deficiency in extracellular matrix binding, BBA Protein and Proteomics, Vol: 1865, Pages: 304-311, ISSN: 1570-9639
Enteroaggregative Escherichia coli (EAEC) is an emerging cause of acute and persistent diarrhea worldwide. The pathogenesis of different EAEC stains is complicated, however, the early essential step begins with attachment of EAEC to intestinal mucosa via aggregative adherence fimbriae (AAFs). Currently, five different variants have been identified, which all share a degree of similarity in the gene organization of their operons and sequences. Here, we report the solution structure of Agg5A from the AAF/V variant. While preserving the major structural features shared by all AAF members, only Agg5A possesses an inserted helix at the beginning of the donor strand, which together with altered surface electrostatics, renders the protein unable to interact with fibronectin. Hence, here we characterize the first AAF variant with a binding mode that varies from previously described AAFs
Hawthorne W, Rouse S, Sewell L, et al., 2016, Structural insights into functional amyloid inhibition in Gram –ve bacteria, Biochemical Society Transactions, Vol: 44, Pages: 1643-1649, ISSN: 1470-8752
Amyloids are proteinaceous aggregates known for their role in debilitating degenerative diseases involving protein dysfunction. Many forms of functional amyloid are also produced in nature and often these systems require careful control of their assembly to avoid the potentially toxic effects. The best-characterised functional amyloid system is the bacterial curli system. Three natural inhibitors of bacterial curli amyloid have been identified and recently characterised structurally. Here, we compare common structural features of CsgC, CsgE and CsgH and discuss the potential implications for general inhibition of amyloid.
Matthews SJ, rouse S, hawthorne, et al., 2016, Purification, crystallization and characterization of the Pseudomonas outer membrane protein FapF, a functional amyloid transporter, Acta Crystallographica Section F: Structural Biology Communications, Vol: F72, Pages: 892-896, ISSN: 2053-230X
Bacteria often produce extracellular amyloid fibresviaa multi-componentsecretion system. Aggregation-prone, unstructured subunits cross the periplasmand are secreted through the outer membrane, after which they self-assemble.Here, significant progress is presented towards solving the high-resolutioncrystal structure of the novel amyloid transporter FapF fromPseudomonas,which facilitates the secretion of the amyloid-forming polypeptide FapC acrossthe bacterial outer membrane. This represents the first step towards obtainingstructural insight into the products of thePseudomonas fapoperon. Initialattempts at crystallizing full-length and N-terminally truncated constructs byrefolding techniques were not successful; however, after preparing FapF106–430from the membrane fraction, reproducible crystals were obtained using thesitting-drop method of vapour diffusion. Diffraction data have been processedto 2.5 A ̊resolution. These crystals belonged to the monoclinic space groupC121,with unit-cell parametersa= 143.4,b= 124.6,c= 80.4 A ̊, = = 90, = 96.32 and three monomers in the asymmetric unit. It was found that the switch tocomplete detergent exchange into C8E4 was crucial for forming well diffractingcrystals, and it is suggested that this combined with limited proteolysis is apotentially useful protocol for membrane -barrel protein crystallography. Thethree-dimensional structure of FapF will provide invaluable information on themechanistic differences of biogenesis between the curli and Fap functionalamyloid systems.
Jia Y, Benjamin S, Liu Q, et al., 2016, Toxoplasma gondii immune mapped protein 1 is anchored to the inner leaflet of the plasma membrane and adopts a novel protein fold, Biochimica et Biophysica Acta - Proteins and Proteomics, Vol: 1865, Pages: 208-219, ISSN: 1570-9639
The immune mapped protein 1 (IMP1) was first identified as a protective antigen in Eimeria maxima and described as vaccine candidate and invasion factor in Toxoplasma gondii. We show here that TgIMP1 localizes to the inner leaflet of plasma membrane (PM) via dual acylation. Mutations either in the N-terminal myristoylation or palmitoylation sites (G2 and C5) cause relocalization of TgIMP1 to the cytosol. The first 11 amino acids are sufficient for PM targeting and the presence of lysine (K7) is critical. Disruption of TgIMP1 gene by double homologous recombination revealed no invasion defect or any measurable alteration in the lytic cycle of tachyzoites. Following immunization with TgIMP1 DNA vaccine, mice challenged with either wild type or IMP1-ko parasites showed no significant difference in protection. The sequence analysis identified a structured C-terminal domain that is present in a broader family of IMP1-like proteins conserved across the members of Apicomplexa. We present the solution structure of this domain determined from NMR data and describe a new protein fold not seen before.
Grundy GJ, Polo LM, Zeng Z, et al., 2016, PARP3 is a sensor of nicked nucleosomes and monoribosylates histone H2B(Glu2)., Nature Communications, Vol: 7, ISSN: 2041-1723
PARP3 is a member of the ADP-ribosyl transferase superfamily that we show accelerates the repair of chromosomal DNA single-strand breaks in avian DT40 cells. Two-dimensional nuclear magnetic resonance experiments reveal that PARP3 employs a conserved DNA-binding interface to detect and stably bind DNA breaks and to accumulate at sites of chromosome damage. PARP3 preferentially binds to and is activated by mononucleosomes containing nicked DNA and which target PARP3 trans-ribosylation activity to a single-histone substrate. Although nicks in naked DNA stimulate PARP3 autoribosylation, nicks in mononucleosomes promote the trans-ribosylation of histone H2B specifically at Glu2. These data identify PARP3 as a molecular sensor of nicked nucleosomes and demonstrate, for the first time, the ribosylation of chromatin at a site-specific DNA single-strand break.
Brown DR, Sheppard CM, Matthews S, et al., 2016, The Xp10 bacteriophage protein P7 inhibits transcription by the major and major variant forms of the host RNA polymerase via a common mechanism, Journal of Molecular Biology, Vol: 428, Pages: 3911-3919, ISSN: 1089-8638
The σ factor is a functionally obligatory subunit of the bacterial transcription machinery, the RNA polymerase. Bacteriophage-encoded small proteins that either modulate or inhibit the bacterial RNAP to allow the temporal regulation of bacteriophage gene expression often target the activity of the major bacterial σ factor, σ70. Previously, we showed that during Xanthomonas oryzae phage Xp10 infection, the phage protein P7 inhibits the host RNAP by preventing the productive engagement with the promoter and simultaneously displaces the σ70 factor from the RNAP. In this study, we demonstrate that P7 also inhibits the productive engagement of the bacterial RNAP containing the major variant bacterial σ factor, σ54, with its cognate promoter. The results suggest for the first time that the major variant form of the host RNAP can also be targeted by bacteriophage-encoded transcription regulatory proteins. Since the major and major variant σ factor interacting surfaces in the RNAP substantially overlap, but different regions of σ70 and σ54 are used for binding to the RNAP, our results further underscore the importance of the σ–RNAP interface in bacterial RNAP function and regulation and potentially for intervention by antibacterials.
Liang X, Liu B, Zhu F, et al., 2016, A distinct sortase SrtB anchors and processes a streptococcal adhesin AbpA with a novel structural property., Scientific Reports, Vol: 6, ISSN: 2045-2322
Surface display of proteins by sortases in Gram-positive bacteria is crucial for bacterial fitness and virulence. We found a unique gene locus encoding an amylase-binding adhesin AbpA and a sortase B in oral streptococci. AbpA possesses a new distinct C-terminal cell wall sorting signal. We demonstrated that this C-terminal motif is required for anchoring AbpA to cell wall. In vitro and in vivo studies revealed that SrtB has dual functions, anchoring AbpA to the cell wall and processing AbpA into a ladder profile. Solution structure of AbpA determined by NMR reveals a novel structure comprising a small globular α/β domain and an extended coiled-coil heliacal domain. Structural and biochemical studies identified key residues that are crucial for amylase binding. Taken together, our studies document a unique sortase/adhesion substrate system in streptococci adapted to the oral environment rich in salivary amylase.
Lee W-C, Matthews S, Garnett JA, 2016, Crystal structure and analysis of HdaB: the Enteroaggregative Escherichia coli AAF/IV pilus tip protein, Protein Science, Vol: 25, Pages: 1898-1905, ISSN: 1469-896X
Enteroaggregative Escherichia coli is the primary cause of pediatric diarrhea indeveloping countries and utilize aggregative adherence fimbriae (AAFs) to promoteinitial adherence to the host intestinal mucosa, promote the formation of biofilms andmediate host invasion. Five AAFs have been identified to date and AAF/IV is amongstthe most prevalent found in clinical isolates. Here we present the X-ray crystal structureof the AAF/IV tip protein HdaB at 2.0 Å resolution. It shares high structural homologywith members of the Afa/Dr superfamily of fimbriae, which are involved in hostinvasion. We highlight surface exposed residues that share sequence homology andpropose that these may function in invasion and also non-conserved regions that couldmediate HdaB specific adhesive functions.
Rasheed M, Garnett J, Perez-Dorado I, et al., 2016, Crystal structure of the CupB6 adhesive tip from the chaperone-usher family of pili from Pseudomonas aeruginosa, Biochimica et Biophysica Acta - Protein Structure, Vol: 1864, Pages: 1500-1505, ISSN: 0005-2795
Pseudomonas aeruginosa is a Gram-negative opportunistic bacterial pathogen that can cause chronicinfection of the lungs of cystic fibrosis patients. Chaperone-usher systems in P. aeruginosa are knownto translocate and assemble adhesive pili on the bacterial surface and contribute to biofilm formationwithin the host. Here, we report the crystal structure of the tip adhesion subunit CupB6 from thecupB1-6 gene cluster. The tip domain is connected to the pilus via the N-terminal donor strand fromthe main pilus subunit CupB1. Although the CupB6 adhesion domain bears structural features similarto other CU adhesins it displays an unusual polyproline helix adjacent to a prominent surface pocket,which are likely the site for receptor recognition.
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