A holin/peptidoglycan hydrolase‐dependent protein secretion system

Palmer, Tracy; Finney, Alexander J.; Saha, Chayan Kumar; Atkinson, Gemma C.; Sargent, Frank

doi:10.1111/mmi.14599

Cited by 65 publications

(81 citation statements)

References 62 publications

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“…Protein secretion systems are found in almost all bacteria and are critical for processes such as nutrient capture and niche adaptation. To date, 10 distinct protein secretion systems (named types I-X) have been identified [1][2][3]. While most of these are exclusive to Gram-negative bacteria, the type VII secretion system (T7SS) is encoded by many Grampositive Actinobacteria and Firmicutes [4,5].…”

Section: Introductionmentioning

confidence: 99%

Extreme genetic diversity in the type VII secretion system of Listeria monocytogenes suggests a role in bacterial antagonism

Bowran

Palmer

2021

Microbiology

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The type VII protein secretion system (T7SS) has been characterized in members of the phyla Actinobacteria and Firmicutes. In mycobacteria the T7SS is intimately linked with pathogenesis and intracellular survival, while in Firmicutes there is mounting evidence that the system plays a key role in interbacterial competition. A conserved membrane-bound ATPase protein, termed EssC in Staphylococcus aureus , is a critical component of the T7SS and is the primary receptor for substrate proteins. Genetic diversity in the essC gene of S. aureus has previously been reported, resulting in four protein variants that are linked to specific subsets of substrates. Here we have analysed the genetic diversity of the T7SS-encoding genes and substrate proteins across Listeria monocytogenes genome sequences. We find that there are seven EssC variants across the species that differ in their C-terminal region; each variant is correlated with a distinct subset of genes for likely substrate and accessory proteins. EssC1 is most common and is exclusively linked with polymorphic toxins harbouring a YeeF domain, whereas EssC5, EssC6 and EssC7 variants all code for an LXG domain protein adjacent to essC. Some essC1 variant strains encode an additional, truncated essC at their T7 gene cluster. The truncated EssC, comprising only the C-terminal half of the protein, matches the sequence of either EssC2, EssC3 or EssC4. In each case the truncated gene directly precedes a cluster of substrate/accessory protein genes acquired from the corresponding strain. Across L. monocytogenes strains we identified 40 LXG domain proteins, most of which are encoded at conserved genomic loci. These loci also harbour genes encoding immunity proteins and sometimes additional toxin fragments. Collectively our findings strongly suggest that the T7SS plays an important role in bacterial antagonism in this species.

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Section: Introductionmentioning

confidence: 99%

Extreme genetic diversity in the type VII secretion system of Listeria monocytogenes suggests a role in bacterial antagonism

Bowran

Palmer

2021

Microbiology

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“…BastionHub will be maintained for at least 5 years and will be periodically updated to keep pace with emerging substrates and new experimental details as they become available. This will include substantial updates in the form of adding the remaining secretion system substrates, potentially including substrates from the recently proposed type 10 secretion system ( 44 ) and the Gram-positive substrates of the T7SS.…”

Section: Discussionmentioning

confidence: 99%

BastionHub: a universal platform for integrating and analyzing substrates secreted by Gram-negative bacteria

Wang

Hou

et al. 2020

Nucleic Acids Research

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Gram-negative bacteria utilize secretion systems to export substrates into their surrounding environment or directly into neighboring cells. These substrates are proteins that function to promote bacterial survival: by facilitating nutrient collection, disabling competitor species or, for pathogens, to disable host defenses. Following a rapid development of computational techniques, a growing number of substrates have been discovered and subsequently validated by wet lab experiments. To date, several online databases have been developed to catalogue these substrates but they have limited user options for in-depth analysis, and typically focus on a single type of secreted substrate. We therefore developed a universal platform, BastionHub, that incorporates extensive functional modules to facilitate substrate analysis and integrates the five major Gram-negative secreted substrate types (i.e. from types I–IV and VI secretion systems). To our knowledge, BastionHub is not only the most comprehensive online database available, it is also the first to incorporate substrates secreted by type I or type II secretion systems. By providing the most up-to-date details of secreted substrates and state-of-the-art prediction and visualized relationship analysis tools, BastionHub will be an important platform that can assist biologists in uncovering novel substrates and formulating new hypotheses. BastionHub is freely available at http://bastionhub.erc.monash.edu/.

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“…Despite the diverse secretion systems now recognized, there are more to be identified based on the fact that some proteins predicted to be secreted lack known secretion pathways (44). The type X secretory pathway was described in 2020 and shed light on long standing mysteries surrounding the dependence on a muramidase for secretion of Typhoid toxin across the cell wall (45). Secretion pathways are the tools with which bacteria interact with their world, and as such each one discovered provides a slightly more complete picture of the toolbox.…”

Section: Discussionmentioning

confidence: 99%

Description of a widespread bacterial secretion system with chemically diverse substrates

Grossman

Mauer

Forest

et al. 2020

Preprint

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In host-associated bacteria, surface and secreted proteins mediate acquisition of nutrients, interactions with host cells, and specificity of host-range and tissue-localization. In Gramnegative bacteria, the mechanism by which many proteins cross, become embedded within, or become tethered to the outer membrane remains unclear. The domain of unknown function (DUF)560 occurs in outer membrane proteins found throughout and beyond the proteobacteria. Functionally characterized DUF560 representatives include NilB, a host-range specificity determinant of the nematode-mutualist Xenorhabdus nematophila and the surface lipoprotein assembly modulators (Slam), Slam1 and Slam2 which facilitate surface exposure of lipoproteins in the human pathogen Neisseria meningitidis. Through network analysis of protein sequence similarity we show that DUF560 subclusters exist and correspond with organism lifestyle rather than with taxonomy, suggesting a role for these proteins in environmental adaptation. Cluster 1 Mauer, Grossman et al. Bacterial Surface/Secreted Protein Associated Outer Membrane Proteins (SPAMs) 2 had the greatest number of representative proteins, was dominated by homologs from animalassociated symbionts, and was composed of subclusters: 1A (containing NilB, Slam1, and Slam2), 1B, and 1C. Genome neighborhood networks revealed that Cluster 1A DUF560 members are strongly associated with TonB, TonB-dependent receptors, and predicted coreceptors such as the Slam1 lipoprotein substrates transferrin binding protein and lactoferrin binding protein. The genome neighborhood network of Cluster 1B sequences are similarly dominated by TonB loci, but typically the associated co-receptors (the presumed DUF560substrates) are predicted to be non-lipidated. We suggest that these subclusters within the DUF560 protein family indicate distinctive activities and that Slam activity may be characteristic of Cluster 1A members but not all DUF560 homologs. For Cluster 1 DUF560 homologs we propose the name SPAM (Surface/Secreted Protein Associated Outer Membrane Proteins) to accommodate the potential for non-lipoprotein substrates or different activities. We show that the repertoire of SPAM proteins in Xenorhabdus correlates with host phylogeny, suggesting that the host environment drives the evolution of these symbiont-encoded proteins. This pattern of selection for specific sequences based on host physiology and/or environmental factors may extend to other clusters of the DUF560 family.

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A holin/peptidoglycan hydrolase‐dependent protein secretion system

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 65 publications

References 62 publications

Extreme genetic diversity in the type VII secretion system of Listeria monocytogenes suggests a role in bacterial antagonism

Extreme genetic diversity in the type VII secretion system of Listeria monocytogenes suggests a role in bacterial antagonism

BastionHub: a universal platform for integrating and analyzing substrates secreted by Gram-negative bacteria

Description of a widespread bacterial secretion system with chemically diverse substrates

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