Imperial College London


Faculty of MedicineNational Heart & Lung Institute

Honorary Research Fellow







G45Emmanuel Kaye BuildingRoyal Brompton Campus





Publication Type

20 results found

Murphy RA, Pizzato J, Cuthbertson L, Sabnis A, Edwards A, Nolan L, Vorup-Jensen T, Larrouy-Maumus G, Davies Jet al., 2023, Antimicrobial peptide glatiramer acetate targets Pseudomonas aeruginosa lipopolysaccharides to breach membranes without altering lipopolysaccharide modification, Nature Portfolio Journals Antimicrobials and Resistance, ISSN: 2731-8745

Antimicrobial peptides (AMPs) are key components of innate immunity across all domains of life. Both natural and synthetic AMPs are receiving renewed attention in the efforts to combat the antimicrobial resistance (AMR) crisis and the loss of antibiotic efficacy. The gram-negative pathogen Pseudomonas aeruginosa is one of the most concerning infecting bacteria in AMR, particularly in people with cystic fibrosis (CF) where respiratory infections are difficult to eradicate and are associated with increased morbidity and mortality. Cationic AMPs exploit the negative charge of lipopolysaccharides (LPS) on P. aeruginosa to bind to and disrupt the bacterial membrane(s) and cause lethal damage. P. aeruginosa modifies its LPS, via environmental or genetic factors, to neutralise the charge of the cell and evade AMP killing. Free-LPS is also a component of CF sputum, as is anionic extracellular DNA (eDNA), each of which can bind AMPs by electrostatic interaction. Both free LPS and eDNA also feed into pro-inflammatory cycles. Glatiramer acetate (GA) is a random peptide co-polymer of glycine, lysine, alanine, and tyrosine and used as drug in the treatment of multiple sclerosis (MS); we have previously shown GA to be an AMP which synergises with tobramycin against P. aeruginosa from CF, functioning via bacterial membrane disruption. Here, we demonstrate direct binding and sequestration/neutralisation of P. aeruginosa LPS in keeping with GA’s ability to disrupt the outer membrane. Binding and neutralisation of eDNA was also seen. At CF-relevant concentrations, however, neither strongly inhibited membrane disruption by GA. Furthermore, in both type strains and clinical CF isolates of P. aeruginosa, exposure to GA did not result in increased modification of the Lipid A portion of LPS or in increased expression of genetically encoded systems involved in AMP sensing and LPS modification. With GA’s low selective pressure on P. aeruginosa for known AMP resistance mechanisms

Journal article

Nolan LM, Allsopp LP, 2022, Antimicrobial Weapons of Pseudomonas aeruginosa, Pseudomonas aeruginosa, Editors: Filloux, Ramos, Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: 223-256, ISBN: 978-3-031-08490-4

Pseudomonas aeruginosa is a robust and versatile organism capable of surviving and prospering in a diverse array of environments and is an opportunistic pathogen of humans. One reason for the success of this pathogen is the large arsenal of antimicrobial weapons that it possesses. Here we focus our attention on these antimicrobial weapons and how they give P. aeruginosa a survival edge in polymicrobial environments. We define antimicrobial weapons as components produced by P. aeruginosa that are used to kill, inhibit growth and/or subvert key cellular functions in other microbes. P. aeruginosa has a large and complex genome and encodes an armament of antimicrobial weapons that fall into two subclasses; those that are delivered directly to competing microbes using a contact-dependent method, and those that are secreted in a contact-independent manner into the environment to then be available to target neighbouring cells. This chapter provides an overview of the major antimicrobial weapons possessed by P. aeruginosa, captures recent advances in the field and discusses how these could be targeted as a therapeutic intervention, or potentially harnessed to combat infection.

Book chapter

Turnbull L, Leigh R, Cavaliere R, Osvath SR, Nolan L, Smyth D, Verhoeven K, Chole RA, Whitchurch CBet al., 2021, Device design modifications informed by in vitro testing of bacterial attachment reduce infection rates of cochlear implants in clinical practice, Microorganisms, Vol: 9, ISSN: 2076-2607

Recalcitrant chronic infections of implanted medical devices are often linked to the presence of biofilms. The prevention and treatment of medical device-associated infections is a major source of antibiotic use and driver of antimicrobial resistance globally. Lowering the incidence of infection in patients that receive implanted medical devices could therefore significantly improve antibiotic stewardship and reduce patient morbidity. Here we determined if modifying the design of an implantable medical device to reduce bacterial attachment, impacted the incidence of device-associated infections in clinical practice. Since the 1980s cochlear implants have provided long-term treatment of sensorineural hearing deficiency in hundreds of thousands of patients world-wide. Nonetheless, a relatively small number of devices are surgically explanted each year due to unresolvable infections. Features associated with the accumulation of bacteria on the Cochlear™ Nucleus® CI24RE™ model of cochlear implant devices were identified using both in vitro bacterial attachment assays and examination of explanted devices. Macro-scale design modifications that reduced bacterial attachment in vitro were incorporated into the design of the CI500™ and Profile™ series of Nucleus implant. Analyses of mandatory post-market vigilance data of 198,757 CI24RE and 123,084 CI500/Profile series implantation surgeries revealed that these design modifications correlated with significantly reduced infection rates. This study demonstrates that a design-centric approach aimed at mitigating bacterial attachment was a simple, and effective means of reducing infections associated with Cochlear Nucleus devices. This approach is likely to be applicable to improving the designs of other implantable medical devices to reduce device-associated infections.

Journal article

Nolan LM, Cain AK, Clamens T, Furniss RCD, Manoli E, Sainz-Polo MA, Dougan G, Albesa-Jove D, Parkhill J, Mavridou DAI, Filloux Aet al., 2021, Identification of tse8 as a type VI secretion system toxin from pseudomonas aeruginosa that targets the bacterial transamidosome to inhibit protein synthesis in prey cells, Nature Microbiology, Vol: 6, Pages: 1199-+, ISSN: 2058-5276

The Type VI secretion system (T6SS) is a bacterial nanomachine that delivers toxic effectors to kill competitors or subvert some of their key functions. Here, we use transposon directed insertion–site sequencing to identify T6SS toxins associated with the H1-T6SS, one of the three T6SS machines found in Pseudomonas aeruginosa. This approach identified several putative toxin–immunity pairs, including Tse8–Tsi8. Full characterization of this protein pair demonstrated that Tse8 is delivered by the VgrG1a spike complex into prey cells where it targets the transamidosome, a multiprotein complex involved in protein synthesis in bacteria that lack either one, or both, of the asparagine and glutamine transfer RNA synthases. Biochemical characterization of the interactions between Tse8 and the transamidosome components GatA, GatB and GatC suggests that the presence of Tse8 alters the fine-tuned stoichiometry of the transamidosome complex, and in vivo assays demonstrate that Tse8 limits the ability of prey cells to synthesize proteins. These data expand the range of cellular components targeted by the T6SS by identifying a T6SS toxin affecting protein synthesis and validate the use of a transposon directed insertion site sequencing–based global genomics approach to expand the repertoire of T6SS toxins in T6SS-encoding bacteria.

Journal article

Mandal PK, Ballerin G, Nolan LM, Petty NK, Whitchurch CBet al., 2021, Bacteriophage infection of Escherichia coli leads to the formation of membrane vesicles via both explosive cell lysis and membrane blebbing, Microbiology, Vol: 167, Pages: 1-9, ISSN: 1350-0872

Membrane vesicles (MVs) are membrane-bound spherical nanostructures that prevail in all three domains of life. In Gram-negative bacteria, MVs are thought to be produced through blebbing of the outer membrane and are often referred to as outer membrane vesicles (OMVs). We have recently described another mechanism of MV formation in Pseudomonas aeruginosa that involves explosive cell-lysis events, which shatters cellular membranes into fragments that rapidly anneal into MVs. Interestingly, MVs are often observed within preparations of lytic bacteriophage, however the source of these MVs and their association with bacteriophage infection has not been explored. In this study we aimed to determine if MV formation is associated with lytic bacteriophage infection. Live super-resolution microscopy demonstrated that explosive cell lysis of Escherichia coli cells infected with either bacteriophage T4 or T7, resulted in the formation of MVs derived from shattered membrane fragments. Infection by either bacteriophage was also associated with the formation of membrane blebs on intact bacteria. TEM revealed multiple classes of MVs within phage lysates, consistent with multiple mechanisms of MV formation. These findings suggest that bacteriophage infection may be a major contributor to the abundance of bacterial MVs in nature.

Journal article

Hynen AL, Lazenby JJ, Savva GM, McCaughey LC, Turnbull L, Nolan LM, Whitchurch CBet al., 2021, Multiple holins contribute to extracellular DNA release in Pseudomonas aeruginosa biofilms, Microbiology, Vol: 167, Pages: 1-12, ISSN: 1350-0872

Bacterial biofilms are composed of aggregates of cells encased within a matrix of extracellular polymeric substances (EPS). One key EPS component is extracellular DNA (eDNA), which acts as a ‘glue’, facilitating cell–cell and cell–substratum interactions. We have previously demonstrated that eDNA is produced in Pseudomonas aeruginosa biofilms via explosive cell lysis. This phenomenon involves a subset of the bacterial population explosively lysing, due to peptidoglycan degradation by the endolysin Lys. Here we demonstrate that in P. aeruginosa three holins, AlpB, CidA and Hol, are involved in Lys-mediated eDNA release within both submerged (hydrated) and interstitial (actively expanding) biofilms, albeit to different extents, depending upon the type of biofilm and the stage of biofilm development. We also demonstrate that eDNA release events determine the sites at which cells begin to cluster to initiate microcolony formation during the early stages of submerged biofilm development. Furthermore, our results show that sustained release of eDNA is required for cell cluster consolidation and subsequent microcolony development in submerged biofilms. Overall, this study adds to our understanding of how eDNA release is controlled temporally and spatially within P. aeruginosa biofilms.

Journal article

Nolan LM, Turnbull L, Katrib M, Osvath SR, Losa D, Lazenby JJ, Whitchurch CBet al., 2020, Pseudomonas aeruginosa is capable of natural transformation in biofilms, Microbiology, Vol: 10, Pages: 995-1003, ISSN: 1350-0872

Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologues of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type-IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa.

Journal article

Nolan LM, McCaughey LC, Merjane J, Turnbull L, Whitchurch CBet al., 2020, ChpC controls twitching motility-mediated expansion of Pseudomonas aeruginosa biofilms in response to serum albumin, mucin and oligopeptides, Microbiology, Vol: 166, Pages: 669-678, ISSN: 1350-0872

Twitching motility-mediated biofilm expansion occurs via coordinated, multi-cellular collective behaviour to allow bacteria to actively expand across surfaces. Type-IV pili (T4P) are cell-associated virulence factors which mediate twitching motility via rounds of extension, surface attachment and retraction. The Chp chemosensory system is thought to respond to environmental signals to regulate the biogenesis, assembly and twitching motility function of T4P. In other well characterised chemosensory systems, methyl-accepting chemotaxis proteins (MCPs) feed environmental signals through a CheW adapter protein to the histidine kinase CheA to modulate motility. The Pseudomonas aeruginosa Chp system has an MCP PilJ and two CheW adapter proteins, PilI and ChpC, that likely interact with the histidine kinase ChpA to feed environmental signals into the system. In the current study we show that ChpC is involved in the response to host-derived signals serum albumin, mucin and oligopeptides. We demonstrate that these signals stimulate an increase in twitching motility, as well as in levels of 3′−5′-cyclic adenosine monophosphate (cAMP) and surface-assembled T4P. Interestingly, our data shows that changes in cAMP and surface piliation levels are independent of ChpC but that the twitching motility response to these environmental signals requires ChpC. Furthermore, we show that protease activity is required for the twitching motility response of P. aeruginosa to environmental signals. Based upon our data we propose a model whereby ChpC feeds these environmental signals into the Chp system, potentially via PilJ or another MCP, to control twitching motility. PilJ and PilI then modulate T4P surface levels to allow the cell to continue to undergo twitching motility. Our study is the first to link environmental signals to the Chp chemosensory system and refines our understanding of how this system controls twitching motility-mediated biofilm expansion in P. aeruginosa

Journal article

Allsopp LP, Bernal P, Nolan LM, Filloux Aet al., 2020, Causalities of war: the connection between type VI secretion system and microbiota, Cellular Microbiology, Vol: 22, Pages: 1-9, ISSN: 1462-5814

Microbiota niches have space and/or nutrient restrictions, which has led to the coevolution of cooperation, specialisation, and competition within the population. Different animal and environmental niches contain defined resident microbiota that tend to be stable over time and offer protection against undesired intruders. Yet fluxes can occur, which alter the composition of a bacterial population. In humans, the microbiota are now considered a key contributor to maintenance of health and homeostasis, and its alteration leads to dysbiosis. The bacterial type VI secretion system (T6SS) transports proteins into the environment, directly into host cells or can function as an antibacterial weapon by killing surrounding competitors. Upon contact with neighbouring cells, the T6SS fires, delivering a payload of effector proteins. In the absence of an immunity protein, this results in growth inhibition or death of prey leading to a competitive advantage for the attacker. It is becoming apparent that the T6SS has a role in modulating and shaping the microbiota at multiple levels, which is the focus of this review. Discussed here is the T6SS, its role in competition, key examples of its effect upon the microbiota, and future avenues of research.

Journal article

Wood TE, Howard SA, Forster A, Nolan LM, Manoli E, Bullen NP, Yau HCL, Hachani A, Hayward RD, Whitney JC, Vollmer W, Freemont PS, Filloux Aet al., 2019, The Pseudomonas aeruginosa T6SS delivers a periplasmic toxin that disrupts bacterial cell morphology, Cell Reports, Vol: 29, Pages: 187-201.e7, ISSN: 2211-1247

The type VI secretion system (T6SS) is crucialin interbacterial competition and is avirulence determinant ofmany Gram-negative bacteria. Several T6SS effectorsarecovalently fused to secreted T6SS structural components such asthe VgrG spike for delivery into target cells.In Pseudomonas aeruginosa, theVgrG2b effector waspreviously proposedto mediatebacterial internalisation into eukaryotic cells. In this work, wefind that the VgrG2b C-terminal domain(VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein.We resolve thestructure of VgrG2bC-ter and confirm it is a member ofthezinc-metallopeptidasefamily of enzymes. We show that this effector causesmembrane blebbing atmidcell, whichsuggests a distincttype of T6SS-mediated growthinhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Ourstudyintroduces a further effector family to the T6SS arsenaland demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells.

Journal article

Cain AK, Nolan LM, Sullivan GJ, Whitchurch CB, Filloux A, Parkhill Jet al., 2019, Complete genome sequence of pseudomonas aeruginosa reference strain PAK, Microbiology Resource Announcements, Vol: 8, ISSN: 2576-098X

We report the complete genome of Pseudomonas aeruginosa strain PAK, a strain which has been instrumental in the study of a range of P. aeruginosa virulence and pathogenesis factors and has been used for over 50 years as a laboratory reference strain.

Journal article

Lorenz A, Preusse M, Bruchmann S, Pawar V, Grahl N, Pils MC, Nolan LM, Filloux A, Weiss S, Haeussler Set al., 2019, Importance of flagella in acute and chronic Pseudomonas aeruginosa infections, Environmental Microbiology, Vol: 21, Pages: 883-897, ISSN: 1462-2912

Pseudomonas aeruginosa is an environmental microorganism and a causative agent of diverse acute and chronic, biofilm‐associated infections. Advancing research‐based knowledge on its adaptation to conditions within the human host is bound to reveal novel strategies and targets for therapeutic intervention. Here, we investigated the traits that P. aeruginosa PA14 as well as a virulence attenuated ΔlasR mutant need to survive in selected murine infection models. Experimentally, the genetic programs that the bacteria use to adapt to biofilm‐associated versus acute infections were dissected by passaging transposon mutant libraries through mouse lungs (acute) or mouse tumours (biofilm‐infection). Adaptive metabolic changes of P. aeruginosa were generally required during both infection processes. Counter‐selection against flagella expression was observed during acute lung infections. Obviously, avoidance of flagella‐mediated activation of host immunity is advantageous for the wildtype bacteria. For the ΔlasR mutant, loss of flagella did not confer a selective advantage. Apparently, other pathogenesis mechanisms are active in this virulence attenuated strain. In contrast, the infective process of P. aeruginosa in the chronic biofilm model apparently required expression of flagellin. Together, our findings imply that the host immune reactions against the infectious agent are very decisive for acuteness and duration of the infectious disease. They direct disease outcome.

Journal article

Nolan LM, Whitchurch CB, Barquist L, Katrib M, Boinett CJ, Mayho M, Goulding D, Charles IG, Filloux A, Parkhill J, Cain AKet al., 2018, A global genomic approach uncovers novel components for twitching motility-mediated biofilm expansion in <i>Pseudomonas aeruginosa</i>, MICROBIAL GENOMICS, Vol: 4, ISSN: 2057-5858

Journal article

Allsopp LP, Wood TE, Howard SA, Maggiorelli F, Nolan LM, Wettstadt S, Filloux Aet al., 2017, RsmA and AmrZ orchestrate the assembly of all three type VI secretion systems in Pseudomonas aeruginosa, Proceedings of the National Academy of Sciences of the United States of America, Vol: 114, Pages: 7707-7712, ISSN: 1091-6490

The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1–Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent. However, study of H2-T6SS and H3-T6SS has been neglected because of a poor understanding of the associated regulatory network. Here we performed a screen to identify H2-T6SS and H3-T6SS regulatory elements and found that the posttranscriptional regulator RsmA imposes a concerted repression on all three T6SS clusters. A higher level of complexity could be observed as we identified a transcriptional regulator, AmrZ, which acts as a negative regulator of H2-T6SS. Overall, although the level of T6SS transcripts is fine-tuned by AmrZ, all T6SS mRNAs are silenced by RsmA. We expanded this concept of global control by RsmA to VgrG spike and T6SS toxin transcripts whose genes are scattered on the chromosome. These observations triggered the characterization of a suite of H2-T6SS toxins and their implication in direct bacterial competition. Our study thus unveils a central mechanism that modulates the deployment of all T6SS weapons that may be simultaneously produced within a single cell.

Journal article

Nolan LM, Cavaliere R, Turnbull L, Whitchurch CBet al., 2015, Extracellular ATP inhibits twitching motility-mediated biofilm expansion by Pseudomonas aeruginosa, BMC Microbiology, Vol: 15

Journal article

Mackie A, Keseler IM, Nolan L, Karp PD, Paulsen ITet al., 2013, Dead End Metabolites - Defining the Known Unknowns of the E. coli Metabolic Network, PLoS ONE, Vol: 8, Pages: e75210-e75210

Journal article

Gloag ES, Turnbull L, Huang A, Vallotton P, Wang H, Nolan LM, Mililli L, Hunt C, Lu J, Osvath SR, Monahan LG, Cavaliere R, Charles IG, Wand MP, Gee ML, Prabhakar R, Whitchurch CBet al., 2013, Self-organization of bacterial biofilms is facilitated by extracellular DNA, Proceedings of the National Academy of Sciences, Vol: 110, Pages: 11541-11546, ISSN: 0027-8424

<jats:p> Twitching motility-mediated biofilm expansion is a complex, multicellular behavior that enables the active colonization of surfaces by many species of bacteria. In this study we have explored the emergence of intricate network patterns of interconnected trails that form in actively expanding biofilms of <jats:italic>Pseudomonas aeruginosa</jats:italic> . We have used high-resolution, phase-contrast time-lapse microscopy and developed sophisticated computer vision algorithms to track and analyze individual cell movements during expansion of <jats:italic>P. aeruginosa</jats:italic> biofilms. We have also used atomic force microscopy to examine the topography of the substrate underneath the expanding biofilm. Our analyses reveal that at the leading edge of the biofilm, highly coherent groups of bacteria migrate across the surface of the semisolid media and in doing so create furrows along which following cells preferentially migrate. This leads to the emergence of a network of trails that guide mass transit toward the leading edges of the biofilm. We have also determined that extracellular DNA (eDNA) facilitates efficient traffic flow throughout the furrow network by maintaining coherent cell alignments, thereby avoiding traffic jams and ensuring an efficient supply of cells to the migrating front. Our analyses reveal that eDNA also coordinates the movements of cells in the leading edge vanguard rafts and is required for the assembly of cells into the “bulldozer” aggregates that forge the interconnecting furrows. Our observations have revealed that large-scale self-organization of cells in actively expanding biofilms of <jats:italic>P. aeruginosa</jats:italic> occurs through construction of an intricate network of furrows that is facilitated by eDNA. </jats:p>

Journal article

Nolan LM, Beatson SA, Croft L, Jones PM, George AM, Mattick JS, Turnbull L, Whitchurch CBet al., 2012, Extragenic suppressor mutations that restore twitching motility to <scp><i>fimL</i></scp> mutants of <i><scp>P</scp>seudomonas aeruginosa</i> are associated with elevated intracellular cyclic <scp>AMP</scp> levels, MicrobiologyOpen, Vol: 1, Pages: 490-501, ISSN: 2045-8827

<jats:title>Abstract</jats:title><jats:p>Cyclic <jats:styled-content style="fixed-case">AMP</jats:styled-content> (<jats:styled-content style="fixed-case">cAMP</jats:styled-content>) is a signaling molecule that is involved in the regulation of multiple virulence systems of the opportunistic pathogen <jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content>seudomonas aeruginosa</jats:italic>. The intracellular concentration of <jats:styled-content style="fixed-case">cAMP</jats:styled-content> in <jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content>. aeruginosa</jats:italic> cells is tightly controlled at the levels of <jats:styled-content style="fixed-case">cAMP</jats:styled-content> synthesis and degradation through regulation of the activity and/or expression of the adenylate cyclases <jats:styled-content style="fixed-case">CyaA</jats:styled-content> and <jats:styled-content style="fixed-case">CyaB</jats:styled-content> or the <jats:styled-content style="fixed-case">cAMP</jats:styled-content> phosphodiesterase <jats:styled-content style="fixed-case">CpdA</jats:styled-content>. Interestingly, mutants of <jats:styled-content style="fixed-case"><jats:italic>fimL</jats:italic></jats:styled-content>, which usually demonstrate defective twitching motility, frequently revert to a wild‐type twitching‐motility phenotype presumably via the acquisition of an extragenic suppressor mutation(s). In this study, we have characterized five independent <jats:styled-content style="fixed-case"><jats:italic>fimL</jats:italic></jats:styled-content> twitching‐motility revertants and have determined that all have increased

Journal article

Coleman NV, Yau S, Wilson NL, Nolan LM, Migocki MD, Ly M, Crossett B, Holmes AJet al., 2011, Untangling the multiple monooxygenases of <i>Mycobacterium chubuense</i> strain NBB4, a versatile hydrocarbon degrader, Environmental Microbiology Reports, Vol: 3, Pages: 297-307, ISSN: 1758-2229

<jats:title>Summary</jats:title><jats:p><jats:italic>Mycobacterium</jats:italic> strain NBB4 was isolated on ethene as part of a bioprospecting study searching for novel monooxygenase (MO) enzymes of interest to biocatalysis and bioremediation. Previous work indicated that strain NBB4 contained an unprecedented diversity of MO genes, and we hypothesized that each MO type would support growth on a distinct hydrocarbon substrate. Here, we attempted to untangle the relationships between MO types and hydrocarbon substrates. Strain NBB4 was shown to grow on C<jats:sub>2</jats:sub>–C<jats:sub>4</jats:sub> alkenes and C<jats:sub>2</jats:sub>–C<jats:sub>16</jats:sub> alkanes. Complete gene clusters encoding six different monooxygenases were recovered from a fosmid library, including homologues of ethene MO (<jats:italic>etnABCD</jats:italic>), propene MO (<jats:italic>pmoABCD</jats:italic>), propane MO (<jats:italic>smoABCD</jats:italic>), butane MO (<jats:italic>smoXYB1C1Z</jats:italic>), cytochrome P450 (CYP153; <jats:italic>fdx‐cyp‐fdr</jats:italic>) and alkB (<jats:italic>alkB‐rubA1‐rubA2</jats:italic>). Catabolic enzymes involved in ethene assimilation (EtnA, EtnC, EtnD, EtnE) and alkane assimilation (alcohol and aldehyde dehydrogenases) were identified by proteomics, and we showed for the first time that stress response proteins (catalase/peroxidase, chaperonins) were induced by growth on C<jats:sub>2</jats:sub>–C<jats:sub>5</jats:sub> alkanes and ethene. Surprisingly, none of the identified MO genes could be specifically associated with oxidation of small alkanes, and thus the nature of the gaseous alkane MO in NBB4 remains mysterious.</jats:p>

Journal article

Keseler IM, Bonavides-Martinez C, Collado-Vides J, Gama-Castro S, Gunsalus RP, Johnson DA, Krummenacker M, Nolan LM, Paley S, Paulsen IT, Peralta-Gil M, Santos-Zavaleta A, Shearer AG, Karp PDet al., 2009, EcoCyc: A comprehensive view of Escherichia coli biology, Nucleic Acids Research, Vol: 37, Pages: D464-D470, ISSN: 0305-1048

Journal article

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