Project description:Bacteria of the genus Xanthomonas are economically important plant pathogens. Pathogenicity of Xanthomonas spp. depends on the type III-secretion system and additional virulence determinants. The number of sequenced Xanthomonas genomes increases rapidly, however, accurate annotation of these genomes is difficult, because it relies on gene prediction programs. In this study, we used a mass-spectrometry (MS)-based approach to identify the proteome of Xanthomonas campestris pv. vesicatoria (Xcv) also known as X. euvesicatoria, a well-studied member of plant-pathogenic Xanthomonadaceae. Results Using different culture conditions, MS-datasets were searched against a six-frame-translated genome database of Xcv. In total, we identified 2,593 proteins covering 55% of the Xcv genome, including 764 hitherto hypothetical proteins. Our proteogenomic approach identified 30 new protein-coding genes and allowed correction of the N-termini of 50 protein-coding genes. For five novel and two N-terminally corrected genes the corresponding proteins were confirmed by immunoblot. Furthermore, our data indicate that two putative type VI-secretion systems encoded in Xcv play no role in bacterial virulence which was experimentally confirmed.
