cDNA-AFLP analysis unravels a genome-wide hrpG-regulon in the plant pathogen Xanthomonas campestris pv. vesicatoria

Noel, L Thieme, F Nennstiel, D Bonas, U

L. Noel et al., cDNA-AFLP analysis unravels a genome-wide hrpG-regulon in the plant pathogen Xanthomonas campestris pv. vesicatoria, MOL MICROB, 41(6), 2001, pp. 1271-1281

41

INGLESE

Article

Microbiology

MOLECULAR MICROBIOLOGY

0950-382X → ACNP

41

6

2001

1271 - 1281

ISI

0950-382X(200109)41:6<1271:CAUAGH>2.0.ZU;2-7

The Hrp type III protein secretion system is essential for pathogenicity of the Gram-negative plant pathogen Xanthomonas campestris pv. vesicatoria. E xpression of the hrp gene cluster is controlled by HrpG, a two-component re sponse regulator, and HrpX, an AraC-type transcriptional activator. Using t he cDNA-AFLP technique, 30 hrpG-induced (hgi) and five hrpG-repressed (hgr) cDNA fragments were identified, defining a large hrpG-regulon in X. campes tris pv. vesicatoria. Expression of most genes in the hrpG-regulon was depe ndent on hrpX. Seven cDNA fragments map to the known hrp gene cluster and f lanking regions. All other genes appear to be scattered over the chromosome and endogenous plasmids. Sequence analysis identified genes encoding putat ive extracellular proteases, a putative transcriptional regulator and XopJ and XopB (Xanthomonas outer proteins), homologues of YopJ from Yersinia spp . and the avirulence protein AvrPphD of Pseudomonas syringae respectively. XopB is secreted by the Hrp type III secretion system. Analysis of deletion mutants in several hgi genes revealed a new virulence locus. This study de monstrates that cDNA-AFLP is a powerful tool to study prokaryotic transcrip tomes and to identify genes contributing to Xanthomonas virulence and putat ive effector proteins.