title: The endo-beta-1,4-glucanase CelA of Clavibacter michiganensis subsp. michiganensis is a pathogenicity determinant required for induction of bacterial wilt of tomato.
abstract: The phytopathogenic bacterium Clavibacter michiganensis subsp. michiganensis NCPPB382, which causes bacterial wilt and canker of tomato, harbors two plasmids, pCM1 (27.35 kb) and pCM2 (72 kb), encoding genes involved in virulence (D. Meletzus, A. Bermpohl, J. Dreier, and R. Eichenlaub, 1993, J. Bacteriol. 175:2131-2136; J. Dreier, D. Meletzus, and R. Eichenlaub, 1997, Mol. Plant-Microbe Interact. 10:195-206). The region of pCM1 carrying the endoglucanase gene celA was mapped by deletion analysis and complementation. RNA hybridization identified a 2.4-knt (kilonucleotide) transcript of the celA structural gene and the transcriptional initiation site was mapped. The celA gene encodes CelA, a protein of 78 kDa (746 amino acids) with similarity to endo-beta-1,4-glucanases of family A1 cellulases. CelA has a three-domain structure with a catalytic domain, a type IIa-like cellulose-binding domain, and a C-terminal domain. We present evidence that CelA plays a major role in pathogenicity, since wilt induction capability is obtained by endoglucanase expression in plasmid-free, nonvirulent strains and by complementation of the CelA- gene-replacement mutant CMM-H4 with the wild-type celA gene.
authors.affiliation: Universität Bielefeld, Fakultät für Biologie, Gentechnologie/Mikrobiologie, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Jahr
authors.forename: J
authors.initials: J
authors.lastname: Dreier
authors.forename: D
authors.initials: D
authors.lastname: Meletzus
authors.forename: R
authors.initials: R
authors.lastname: Bahro
authors.forename: R
authors.initials: R
authors.lastname: Eichenlaub
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002480:Cellulase / Q000235:genetics* / Q000378:metabolism; D016384:Consensus Sequence; D005798:Genes, Bacterial; D006090:Gram-Negative Bacteria / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D018551:Solanum lycopersicum / Q000382:microbiology*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D010957:Plasmids; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics
chemical_list: C074775:CelA endoglucanase; D002480:Cellulase