| 1. |
- Järvå, Michael A., et al.
(författare)
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Polymer Adhesin Domains in Gram-Positive Cell Surface Proteins
- 2020
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Surface proteins in Gram-positive bacteria are often involved in biofilm formation, host-cell interactions, and surface attachment. Here we review a protein module found in surface proteins that are often encoded on various mobile genetic elements like conjugative plasmids. This module binds to different types of polymers like DNA, lipoteichoic acid and glucans, and is here termed polymer adhesin domain. We analyze all proteins that contain a polymer adhesin domain and classify the proteins into distinct classes based on phylogenetic and protein domain analysis. Protein function and ligand binding show class specificity, information that will be useful in determining the function of the large number of so far uncharacterized proteins containing a polymer adhesin domain.
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| 2. |
- Schmitt, Andreas, et al.
(författare)
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Enterococcal PrgA Extends Far Outside the Cell and Provides Surface Exclusion to Protect against Unwanted Conjugation
- 2020
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Ingår i: Journal of Molecular Biology. - : Elsevier. - 0022-2836 .- 1089-8638. ; 432:20, s. 5681-5695
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Tidskriftsartikel (refereegranskat)abstract
- Horizontal gene transfer between Gram-positive bacteria leads to a rapid spread of virulence factors and antibiotic resistance. This transfer is often facilitated via type 4 secretion systems (T4SS), which frequently are encoded on conjugative plasmids. However, donor cells that already contain a particular conjugative plasmid resist acquisition of a second copy of said plasmid. They utilize different mechanisms, including surface exclusion for this purpose. Enterococcus faecalis PrgA, encoded by the conjugative plasmid pCF10, is a surface protein that has been implicated to play a role in both virulence and surface exclusion, but the mechanism by which this is achieved has not been fully explained. Here, we report the structure of full-length PrgA, which shows that PrgA protrudes far out from the cell wall (approximately 40 nm), where it presents a protease domain. In vivo experiments show that PrgA provides a physical barrier to cellular adhesion, thereby reducing cellular aggregation. This function of PrgA contributes to surface exclusion, reducing the uptake of its cognate plasmid by approximately one order of magnitude. Using variants of PrgA with mutations in the catalytic site we show that the surface exclusion effect is dependent on the activity of the protease domain of PrgA. In silico analysis suggests that PrgA can interact with another enterococcal adhesin, PrgB, and that these two proteins have co-evolved. PrgB is a strong virulence factor, and PrgA is involved in post-translational processing of PrgB. Finally, competition mating experiments show that PrgA provides a significant fitness advantage to plasmid-carrying cells.
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