The lytic transglycosylase, LtgG, controls cell morphology and virulence in Burkholderia pseudomallei

Wallis, Russell; Allcock, Natalie; Barnes, Kay B.; Richards, Mark I.; Auty, Joss M.; Galyov, Edouard E.; Harding, Sarah V.; Mukamolova, Galina V.

doi:10.1038/s41598-019-47483-z

Cited by 13 publications

(22 citation statements)

References 60 publications

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“…As for B. contaminans, in addition to harboring elements of both the T4SS and Type II secretion system (T2SS), the plasmids have a soluble lytic murein transglycosylase harboring a putative invasion domain LysM at a mean copy number of 3 ± 2.8. The lytic transglycosylase, LtgG, has recently reported for its role to control cell morphology and virulence in Burkholderia pseudomallei [32]. Furthermore, we see each harboring a copy of the toxin component of the MazEF toxin-antitoxin system suggesting these ISS B. contaminans isolates may be able to control their transition to the dormant persister state [33].…”

Section: Plasmid Analysismentioning

confidence: 52%

“…Both possess annotated T4SS and T2SS components as well as a soluble lytic murein transglycosylase harboring a putative invasion domain LysM at a mean copy number of 3 ± 2.83 ( Table 5). The lytic transglycosylase, LtgG, has recently reported for its role to control cell morphology in Burkholderia pseudomallei and its virulence in the BALB-C mouse model [32]. Both also harbor a copy of the toxin component of the MazEF toxin-antitoxin system, suggesting the possibility for these ISS B. contaminans isolates to control their transition to the dormant persister state.…”

Section: Plasmid Analysismentioning

confidence: 99%

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Genomic and phenotypic characterization of Burkholderia isolates from the potable water system of the International Space Station

et al. 2020

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Section: Plasmid Analysismentioning

confidence: 52%

Section: Plasmid Analysismentioning

confidence: 99%

Genomic and phenotypic characterization of Burkholderia isolates from the potable water system of the International Space Station

et al. 2020

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“…As for B. contaminans , in addition to harboring elements of both the T4SS and Type II secretion system (T2SS), the plasmids have a soluble lytic murein transglycosylase harboring a putative invasion domain LysM at a mean copy number of 3 ± 2.8. The lytic transglycosylase, LtgG, has recently reported for its role to control cell morphology and virulence in Burkholderia pseudomallei [25]. Furthermore, we see each harboring a copy of the toxin component of the MazEF toxin-antitoxin system suggesting these ISS B. contaminans isolates may be able to control their transition to the dormant persister state [26].…”

Section: Resultsmentioning

confidence: 67%

“…Both possess annotated T4SS and T2SS components as well as a soluble lytic murein transglycosylase harboring a putative invasion domain LysM at a mean copy number of 3 ± 2.83. The lytic transglycosylase, LtgG, has recently reported for its role to control cell morphology in Burkholderia pseudomallei and its virulence in the BALB-C mouse model [25]. Both also harbor a copy of the toxin component of the MazEF toxin-antitoxin system suggesting the ability for these ISS B. contaminans isolates to control their transition to the dormant persister state.…”

Section: Discussionmentioning

confidence: 99%

Genomic and phenotypic characterization ofBurkholderiaisolates from the potable water system of the International Space Station

O’Rourke

Lee

Nierman

et al. 2019

Preprint

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The opportunistic pathogens Burkholderia cepacia and Burkholderia contaminans, both genomovars of the Burkholderia cepacia complex (BCC), are frequently cultured from the potable water system (PWS) of the International Space Station (ISS). Here, we sequenced the genomes and conducted phenotypic assays to characterize these Burkholderia isolates. All recovered isolates of the two species fall within monophyletic clades based on phylogenomic trees of conserved single-copy core genes. Within species, the ISS PWS strains all demonstrate greater than 99% average nucleotide identity (ANI), suggesting that they are of a highly similar genomic lineage and both individually may have stemmed from the two founding clonal strains before diverging into two unique sub strain populations. No evidence for horizontal gene transfer between the populations was observed. Differences between the recovered isolates can be observed at the pangenomic level, particularly within putative plasmids identified within the B. cepacia group. Phenotypically, the ISS-derived B. cepacia isolates generally exhibit a trend of lower rates and shorter duration of macrophage intracellularization compared to the selected terrestrial reference strain (though not significantly), and significantly lower rates of cellular lysis in 7 of the 19 isolates. ISS-derived B. contaminans isolates displayed no difference in rates of macrophage intracellularization compared to the selected reference, though generally increased rates lysis, with 2 of the 5 significantly increased at 12-hours post inoculation. We additionally find that ISS-isolated B. contaminans display hemolytic activity at 37°C not demonstrated by the terrestrial control, and greater antifungal capacity in the more recently collected isolates. Thankfully, the ISS-derived isolates generally exhibit 1-4 times greater sensitivity to common antibiotics used in their clinical treatments. Thus, despite their infection potential, therapeutic treatment should still have efficacy.Author SummaryThe International Space Station (ISS) is a unique built environment due to its isolation and recycling of air and water. Both microbes and astronauts inhabit the ISS, and the potential pathogenicity of the former is of great concern for the safety of the latter. The potable water dispenser (PWD) of the potable water system (PWS) on board the ISS was assembled in a cleanroom facility and then primed on Earth using an extensive process to ensure no gas bubbles existed within the lines that could lock the apparatus upon installation in orbit. The primed system sat dormant for 6 months before installation on the ISS. Microbial surveillance was conducted on the system after installation and the bacterial load was 85 CFU/mL, which exceeded the 50 CFU/mL limits set for ISS potable water. Over a microbial surveillance spanning 4.5 years, numerous strains of the potential pathogen Burkholderia have been isolated from the PWD. Here we sequenced and analyzed the genomes of these strains while also characterizing their potential pathogenicity. The genome analysis indicates it is likely that there were only two strains that were introduced on Earth that have subsequently undergone minimal diverging evolution. These strains retain pathogenicity, but remain susceptible to antibiotics, providing a potential therapeutic intervention in the event of infection.

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“…In fact, Gram-negative bacteria recycle up to 60% of their PG with every generation, suggesting that both PG synthesis and PG recycling are dynamic (Dhar, 2018, Typas, 2011, Park, 2008). A number of proteins are involved in these processes and, while they are well-characterized in E. coli , very little is known about these pathways in intracellular pathogens such as Burkholderia pseudomallei , Legionella pneumophila , or F. tularensis (van Heijenoort, 2011, Jenkins, 2019, Spidlova, 2018, Kijek, 2019).…”

Section: Discussionmentioning

confidence: 99%

A Francisella tularensis L,D-carboxypeptidase plays important roles in cell morphology, envelope integrity, and virulence

Zellner

Mengin‐Lecreulx

Tully

et al. 2019

Preprint

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word count: 192 21 Text word count: 9082 22 Abstract 23 F. tularensis is a Gram-negative, intracellular bacterium that causes the zoonotic disease 24 tularemia. Intracellular pathogens, including F. tularensis, have evolved mechanisms to allow 25survival in the harsh environment of macrophages and neutrophils, where they are exposed to 26 cell membrane-damaging molecules. One mechanism that protects intracellular Gram-negative 27 bacteria from macrophage or neutrophil killing is the ability to recycle and repair damaged 28 peptidoglycan (PG),a process that requires over 50 different PG synthesis and recycling 29 enzymes. In addition to PG repair, PG recycling occurs during cell division and plays critical 30 roles in maintaining cell morphology, structure, and membrane integrity. Here, we identified a 31 PG recycling enzyme, L,D-carboxypeptidase A (LdcA), of F. tularensis that is responsible for 32 converting PG tetrapeptide stems to tripeptide stems. Unlike prototypic LdcA homologs, F. 33 tularensis LdcA is outer membrane-associated and also exhibits L,D-endopeptidase activity, 34 converting PG pentapeptide stems to tripeptide stems. Loss of F. tularensis LdcA led to altered 35 cell morphology and membrane integrity, as well as attenuation in a mouse pulmonary infection 36 model and in primary and immortalized macrophages. Finally, a F. tularensis LdcA mutant 37 protected mice against virulent Type A F. tularensis SchuS4 pulmonary challenge. 38 39 Importance: PG is well known to play important roles in protecting bacteria from external 40 insults and osmotic stress. However, pathogenic bacteria modify their PG architecture to avoid 41 antibiotic activity and/or encode PG recycling and repair pathways to promote bacterial 42 virulence. Prototypic Gram-negative bacteria, including E. coli and Pseudomonas aeruginosa, 43 recycle PG in a multi-enzyme pathway, including the cytoplasmic L,D-carboxypeptidase, LdcA.44Here, we demonstrated that a previously unstudied protein from the intracellular bacterium F. tularensis contains an LdcA conserved domain, this F. tularensis LdcA is outer membrane-46 associated, and deletion of this LdcA ortholog increases bacterial outer membrane thickness, 47 resulting in bacteria that are more resistant to various stressors (e.g., H 2 O 2 , NaCl, low pH), yet 48 are completely attenuated in a mouse pulmonary infection model. Finally, we demonstrated that 49 the F. tularensis LdcA mutant can be used as a live, attenuated vaccine to protect against 50 pulmonary challenge with fully virulent F. tularensis. 51 52 53 54 The Gram-negative bacterial cell wall plays an important role in maintaining cell shape, 55 protecting against external insults, and preventing cell lysis amid fluctuations in internal turgor 56 pressure (1). The cell wall is composed of peptidoglycan (PG), a network of alternating N-57 acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) glycan chains that are 58 crosslinked through peptide stems, and lies just outside of the cytoplasmic membrane of most 59 bac...

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The lytic transglycosylase, LtgG, controls cell morphology and virulence in Burkholderia pseudomallei

Cited by 13 publications

References 60 publications

Genomic and phenotypic characterization of Burkholderia isolates from the potable water system of the International Space Station

Genomic and phenotypic characterization of Burkholderia isolates from the potable water system of the International Space Station

Genomic and phenotypic characterization ofBurkholderiaisolates from the potable water system of the International Space Station

A Francisella tularensis L,D-carboxypeptidase plays important roles in cell morphology, envelope integrity, and virulence

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