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