Pseudomonas aeruginosatype IV minor pilins and PilY1 regulate virulence by modulating FimS-AlgR activity

Abstract

10Type IV pili are expressed by a wide range of prokaryotes, including the opportunistic 11 pathogen Pseudomonas aeruginosa. These flexible fibres mediate twitching motility, biofilm 12 maturation, surface adhesion, and virulence. The pilus is composed mainly of major pilin 13 subunits while the low abundance minor pilins FimU-PilVWXE, plus the putative adhesin PilY1, 14 prime pilus assembly and are proposed to form the pilus tip. The minor pilins and PilY1 are 15 encoded in an operon that is positively regulated by the FimS-AlgR two-component system. 16Independent of pilus assembly, PilY1 is proposed to be a mechanosensory component that -in and pilY1 mutants had reduced virulence towards Caenorhabditis elegans relative to wild type or 20 a major pilin mutant, implying a role in pathogenicity that is independent of pilus assembly. We 21 hypothesized that loss of specific minor pilins relieves feedback inhibition on FimS-AlgR, 22increasing transcription of the minor pilin operon and other members of the AlgR regulon. 23. CC-BY-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/192062 doi: bioRxiv preprint first posted online Sep. 21, 2017

The Xanthomonas oryzae pv. oryzae type IV pilus alignment subcomplex protein PilN contributes to regulation of bacterial surface‐associated behaviours and T3SS system

“…It is generally thought that a mucoid strain would produce more EPS (Marko et al , ), and this is in agreement with our results that the mucoid pilN mutant produced enhanced EPS compared to the wild‐type strain. In addition, increased biofilm formation was observed in the pilN mutant, consistent with previous reports showing that EPS production has a positive correlation with biofilm formation in Xanthomonas species (Buttner and Bonas, ).…”

“…The qualitative analysis and quantitative measurement by crystal violet staining showed that PΔ pilN had greater biofilm production than the wild type, whilst biofilm production in the complementary strain CPΔ pilN was similar to the wild type (Figure a). The phenotype of mucoid colony of PΔ pilN was speculated to be related to the EPS production (Rosenberg et al , ; Marko et al , ). Therefore, the production of EPS was compared between the wild type PXO99 A , PΔ pilN , and CPΔ pilN .…”

“…Consistent with this, past studies on P . aeruginosa have demonstrated that increased mucoidy, by mutation of the mucA or mucD genes, reduced nematode killing (Marko et al , ). Therefore, we speculate that enhanced EPS and biofilm formation may not endow the pilN mutant with more virulence than the wild type, suggesting that Xoo pathogenesis is multifactorial or there is interplay between virulence factors in Xoo.…”

“…T4P are classified into type IVa (T4aP) and type IVb (T4bP) based on the features of major pilin protein PilA and the organization of T4P biogenesis‐associated genes (Giltner et al , ). T4aP (hereby referred to as T4P) are found in human and animal bacteria such as Pseudomonas and Neisseria (Kolappan et al , ; Marko et al , ), as well as in environmental bacteria such as Myxococcus (Chang et al , ). Recently, a complete architecture of the T4aP machine (T4PM) of Myxococcus xanthus was mapped by cryoelectron tomography.…”

CryoEM map of Pseudomonas aeruginosa PilQ enables structural characterization of TsaP

“…At the pilus base, the inner membrane protein PilC and cytoplasmic ATPase motors, PilB and PilT, catalyze polymerization and depolymerization, respectively (McCallum et al, 2017(McCallum et al, , 2019a. Minor pilins and PilY1 initiate pilus polymerization and are thus thought to localize at the pilus tip (Marko et al, 2018;Nguyen et al, 2015). The pilus exits the periplasm through an outer membrane pore formed by PilQ oligomers.…”