The truA gene of Pseudomonas aeruginosa is required for the expression of type III secretory genes

Ahn, Ki Hoon; Ha, Un-Hwan; Jia, Jinghua; Wu, Donghai; Jin, Shouguang

doi:10.1099/mic.0.26652-0

Cited by 27 publications

(27 citation statements)

References 65 publications

(55 reference statements)

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“…1). Consistent with previous reports (1,20,50), both mutants were defective in twitching motility despite having wild-type levels of intracellular pilins, were susceptible to killing with pilus-specific PO4 bacteriophage, and could be complemented to wild-type motility by provision of fimV in trans (not shown). Based on these phenotypes, the lack of twitching was hypothesized to be due to aberrant pilus assembly that is sufficient for phage infection but not for motility.…”

Section: Features Of the Fimv Protein P Aeruginosasupporting

confidence: 78%

“…Based on the presence of a putative peptidoglycan (PG)-binding LysM motif (so called because it is found in PG-hydrolyzing autolysins) in the N-terminal domain of the protein and evidence that overexpression of FimV caused filamentation of actively twitching cells, FimV was speculated to play a role in restructuring of the PG layer to allow passage of the components of the T4P system (50). The fimV gene is located upstream of truA, a gene required for type III secretion (T3S), but mutagenesis studies showed that FimV is not involved in T3S (1).…”

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confidence: 99%

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The Peptidoglycan-Binding Protein FimV Promotes Assembly of the Pseudomonas aeruginosa Type IV Pilus Secretin

et al. 2011

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The Pseudomonas aeruginosa inner membrane protein FimV is among several proteins of unknown function required for type IV pilus-mediated twitching motility, arising from extension and retraction of pili from their site of assembly in the inner membrane. The pili transit the periplasm and peptidoglycan (PG) layer, ultimately exiting the cell through the PilQ secretin. Although fimV mutants are nonmotile, they are susceptible to killing by pilus-specific bacteriophage, a hallmark of retractable surface pili. Here we show that levels of recoverable surface pili were markedly decreased in fimV pilT retraction-deficient mutants compared with levels in the pilT control, demonstrating that FimV acts at the level of pilus assembly. Levels of inner membrane assembly subcomplex proteins PilM/N/O/P were decreased in fimV mutants, but supplementation of these components in trans did not restore pilus assembly or motility. Loss of FimV dramatically reduced the levels of the PilQ secretin multimer through which pili exit the cell, in part due to decreased levels of PilQ monomers, while PilF pilotin levels were unchanged. Expression of pilQ in trans in the wild type or fimV mutants increased total PilQ monomer levels but did not alter secretin multimer levels or motility. PG pulldown assays showed that the N terminus of FimV bound PG in a LysM motif-dependent manner, and a mutant with an in-frame chromosomal deletion of the LysM motif had reduced motility, secretin levels, and surface piliation. Together, our data show that FimV's role in pilus assembly is to promote secretin formation and that this function depends upon its PG-binding domain.Type IV pili (T4P) are thin, long, flexible, and retractable protein filaments. The broad distribution of T4P among bacterial genera correlates with their ability to mediate a wide range of functions, including attachment to surfaces, DNA uptake, and twitching motility. During twitching motility, pili extend from the cell and attach to a surface, and pilus retraction occurs, moving the bacteria forward toward the point of adhesion (41,51). T4P have been classified into two distinct subtypes, T4aP and T4bP, based on differences in structure of the major pilin subunit and in architecture of the assembly systems (3,16,43). T4aP have been characterized extensively in species such as Pseudomonas aeruginosa, Neisseria spp., and Myxococcus xanthus (10,22,23,39,40,46,49,52). T4bP are found predominately in enteric pathogens, where they promote adhesion (37,58) and bacterial aggregation (6).In P. aeruginosa, a large number of genes involved in the regulation, assembly, and dynamics of T4aP function have been identified. These include the major pilin subunit PilA, as well as a conserved set of minor pilin-like proteins (21); the N-methyltransferase/peptidase PilD, essential for processing prepilins into their mature form (53); an inner membrane assembly subcomplex composed of PilM/N/O/P (4, 47); an outer membrane PilQ secretin pore oligomerized with the assistance of the lipoprotein PilF (7, 29); a...

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Section: Features Of the Fimv Protein P Aeruginosasupporting

confidence: 78%

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confidence: 99%

The Peptidoglycan-Binding Protein FimV Promotes Assembly of the Pseudomonas aeruginosa Type IV Pilus Secretin

et al. 2011

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“…The former gene encodes a well-known global regulator that controls several processes (expression of genes encoding proteases, exotoxin A, twitching motility and QS) (Albus et al, 1997;Beatson et al, 2002;Suh et al, 2002;Kanack et al, 2006;Fox et al, 2008) and the latter encodes a protein involved in type IV pili assembly but has been poorly studied so far (Semmler et al, 2000;Ahn et al, 2004). Both genes were also reported to be required for twitching motility and indeed, as expected, we observed that the selected mutants were impaired for this movement mode (data not shown).…”

Section: Genes Involved In the Regulation Of Expression Of The Paqa Omentioning

confidence: 99%

Role of fimV in type II secretion system-dependent protein secretion of Pseudomonas aeruginosa on solid medium

et al. 2011

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Although classical type II secretion systems (T2SSs) are widely present in Gram-negative bacteria, atypical T2SSs can be found in some species. In Pseudomonas aeruginosa, in addition to the classical T2SS Xcp, it was reported that two genes, xphA and xqhA, located outside the xcp locus were organized in an operon (PaQa) which encodes the orphan PaQa subunit. This subunit is able to associate with other components of the classical Xcp machinery to form a functional hybrid T2SS. In the present study, using a transcriptional lacZ fusion, we found that the PaQa operon was more efficiently expressed (i) on solid LB agar than in liquid LB medium, (ii) at 25 °C than at 37 °C and (iii) at an early stage of growth. These results suggested an adaptation of the hybrid system to particular environmental conditions. Transposon mutagenesis led to the finding that vfr and fimV genes are required for optimal expression of the orphan PaQa operon in the defined growth conditions used. Using an original culturing device designed to monitor secretion on solid medium, the ring-plate system, we found that T2SS-dependent secretion of exoproteins, namely the elastase LasB, was affected in a fimV deletion mutant. Our findings led to the discovery of an interplay between FimV and the global regulator Vfr triggering the modulation of the level of Vfr and consequently the modulation of T2SS-dependent secretion on solid medium.

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“…The former includes a membrane-associated adenylcyclase (CyaB) and a cyclic AMP binding cyclic AMP receptor protein (CRP) homolog called Vfr (53), an Rhl quorum-sensing system (4,22), stationary-phase sigma factor RpoS and its transcriptional activator PsrA (22,41), and a hybrid sensor kinase/response regulator (RtsM/RetS) (19). The latter includes aceA and aceB, encoding the subunits of pyruvate dehydrogenase (11); trpA and kynA, encoding tryptophan synthase and tryptophan dioxygenase (40); truA, encoding pseudouridinase enzyme (1); and mgtE, a magnesium transporter gene (2).…”

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MexT Regulates the Type III Secretion System through MexS and PtrC in Pseudomonas aeruginosa

et al. 2011

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The type III secretion system (T3SS) is the most important virulence factor in Pseudomonas aeruginosa, and its expression level varies in different isolates. We studied the molecular basis for such differences in two laboratory strains, PAK and PAO1. A chromosomal clone library from the high-T3SS-producer strain PAK was introduced into the low-producer strain PAO1, and we found that a mexS gene from PAK confers high T3SS expression in the PAO1 background. Further tests demonstrated that both mexS and its neighboring mexT gene are required for the repression of the T3SS in PAO1, while the PAK genome encodes a defective MexS, accounting for the derepression of the T3SS in PAK and the dominant negative effect when it is introduced into PAO1. MexS is a probable oxidoreductase whose expression is dependent on MexT, a LysR-type transcriptional regulator. Various genetic data support the idea that MexS modulates the transcriptional regulator function of MexT. In searching for the MexT-dependent repressor of the T3SS, a small gene product of PA2486 (ptrC) was found effective in suppressing the T3SS upon overexpression. However, deletion of ptrC in the PAO1 background did not result in derepression of the T3SS, indicating the presence of another repressor for the T3SS. Interestingly, overexpression of functional mexS alone was sufficient to repress T3SS even in the absence of MexT, suggesting that MexS is another mediator of MexT-dependent T3SS repression. Overexpression of mexS alone had no effect on the well-known MexT-dependent genes, including those encoding MexEF efflux pump, elastase, and pyocyanin, indicating alternative regulatory mechanisms. A model has been proposed for the MexS/MexT-mediated regulation of the T3SS, the MexEF efflux pump, and the production of elastase and pyocyanin.

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The truA gene of Pseudomonas aeruginosa is required for the expression of type III secretory genes

Cited by 27 publications

References 65 publications

The Peptidoglycan-Binding Protein FimV Promotes Assembly of the Pseudomonas aeruginosa Type IV Pilus Secretin

The Peptidoglycan-Binding Protein FimV Promotes Assembly of the Pseudomonas aeruginosa Type IV Pilus Secretin

Role of fimV in type II secretion system-dependent protein secretion of Pseudomonas aeruginosa on solid medium

MexT Regulates the Type III Secretion System through MexS and PtrC in Pseudomonas aeruginosa

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