3 research outputs found
Contribution of the Twin Arginine Translocation system to the exoproteome of Pseudomonas aeruginosa
The opportunistic pathogen Pseudomonas aeruginosa uses secretion systems to
deliver exoproteins into the environment. These exoproteins contribute to
bacterial survival, adaptation, and virulence. The Twin arginine translocation
(Tat) export system enables the export of folded proteins into the periplasm,
some of which can then be further secreted outside the cell. However, the full
range of proteins that are conveyed by Tat is unknown, despite the importance
of Tat for the adaptability and full virulence of P. aeruginosa. In this work,
we explored the P. aeruginosa Tat-dependent exoproteome under phosphate
starvation by two-dimensional gel analysis. We identified the major secreted
proteins and new Tat-dependent exoproteins. These exoproteins were further
analyzed by a combination of in silico analysis, regulation studies, and
protein localization. Altogether we reveal that the absence of the Tat system
significantly affects the composition of the exoproteome by impairing protein
export and affecting gene expression. Notably we discovered three new Tat
exoproteins and one novel type II secretion substrate. Our data also allowed
the identification of two new start codons highlighting the importance of
protein annotation for subcellular predictions. The new exoproteins that we
identify may play a significant role in P. aeruginosa pathogenesis, host
interaction and niche adaptation
Conserved network of proteins essential for bacterial viability
The yjeE, yeaZ, and ygjD genes are highly conserved in the genomes of eubacteria, and ygjD orthologs are also found throughout the Archaea and eukaryotes. In this study, we have constructed conditional expression strains for each of these genes in the model organism Escherichia coli K12. We show that each gene is essential for the viability of E. coli under laboratory growth conditions. Growth of the conditional strains under nonpermissive conditions results in dramatic changes in cell ultrastructure. Deliberate repression of the expression of yeaZ results in cells with highly condensed nucleoids, while repression of yjeE and ygjD expression results in at least a proportion of very enlarged cells with an unusual peripheral distribution of DNA. Each of the three conditional expression strains can be complemented by multicopy clones harboring the rstA gene, which encodes a two-component-system response regulator, strongly suggesting that these proteins are involved in the same essential cellular pathway. The results of bacterial two-hybrid experiments show that YeaZ can interact with both YjeE and YgjD but that YgjD is the preferred interaction partner. The results of in vitro experiments indicate that YeaZ mediates the proteolysis of YgjD, suggesting that YeaZ and YjeE act as regulators to control the activity of this protein. Our results are consistent with these proteins forming a link between DNA metabolism and cell division