Transcriptional analysis of pmeA gene encoding a pectin methylesterase in Xanthomonas campestris pv. campestris

• Published in: Research in microbiology Vol. 162; no. 3; pp. 270 - 278
• Main Authors: Hsiao, Yi-Min, Liu, Yu-Fan, Huang, Yi-Ling, Lee, Pei-Yu
• Format: Journal Article
• Language: English
• Published: France Elsevier SAS 01.04.2011
• Subjects: Amino Acid Sequence; Artificial Gene Fusion; Bacterial Proteins - metabolism; Black rot; Brassicaceae; Carboxylic Ester Hydrolases - biosynthesis; Carboxylic Ester Hydrolases - genetics; Catabolite repression; Cyclic AMP; Cyclic AMP receptor protein-like protein; Enoyl-CoA hydratase; Enoyl-CoA Hydratase - metabolism; exopolysaccharides; Extracellular enzymes; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial; genes; Genes, Reporter; Molecular Sequence Data; osmolarity; Oxygen; Pectin methylesterase; Pectinesterase; production economics; Promoter- lacZ reporter assay; Sequence Homology, Amino Acid; transcription (genetics); Transcription Factors - metabolism; Transcription initiation; Transcription Initiation Site; Transcriptional regulation; Virulence; Xanthomonas; Xanthomonas campestris; Xanthomonas campestris - enzymology; Xanthomonas campestris - genetics; Xanthomonas campestris pv. campestris; Xanthomonas campestris pv. campestris; Transcriptional regulation; Promoter- lacZ reporter assay; Pectin methylesterase; Cyclic AMP receptor protein-like protein
• ISSN: 0923-2508; 1769-7123; 1769-7123
• DOI: 10.1016/j.resmic.2010.12.002

Exopolysaccharides and several extracellular enzymes of Xanthomonas campestris pv. campestris (Xcc), the causative agent of black rot in crucifers, are virulence determinants. It is known that Clp (cAMP receptor protein-like protein) and RpfF (an enoyl-CoA hydratase homologue required for the synthesis of the diffusible signal factor, DSF) regulate production of these factors. In this study, plate assay revealed that Xcc possesses pectin methylesterase activity and that its expression is controlled by Clp and RpfF. Mutational analysis has demonstrated that pmeA encodes a pectin methylesterase. Using the 5′ RACE method, the pmeA transcription initiation site was mapped. Transcriptional fusion assays showed that pmeA transcription is positively regulated by Clp and RpfF, subject to catabolite repression which is independent of Clp or RpfF, and repressed under conditions of high osmolarity or oxygen limitation. This study not only extends previous work on Clp and RpfF regulation by showing that they both influence the expression of pmeA in Xcc, but also, for the first time, characterizes pectin methylesterase gene expression in Xanthomonas.