Characterization of the plasmid encoded virulence region pat-1 of phytopathogenic Clavibacter michiganensis subsp. michiganensis

• Published in: Molecular plant-microbe interactions Vol. 10; no. 2; pp. 195 - 206
• Main Authors: Dreier, J. (Universitat Bielefeld, Bielefeld, Germany.), Meletzus, D, Eichenlaub, R
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01-03-1997; The American Phytopathological Society
• Subjects: ADN; Amino Acid Sequence; ARN MENSAJERO; ARN MESSAGER; Bacillus subtilis - genetics; Bacterial plant pathogens; Base Sequence; Biological and medical sciences; Chromosome Mapping; CLAVIBACTER MICHIGANENSIS; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; DNA, Bacterial - genetics; Escherichia coli - genetics; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; GENES; Genes, Bacterial; gram-positive bacteria; Gram-Positive Bacteria - genetics; Gram-Positive Bacteria - pathogenicity; LYCOPERSICON ESCULENTUM; Lycopersicon esculentum - microbiology; Molecular Sequence Data; MUTACION INDUCIDA; MUTATION PROVOQUEE; Nucleic Acid Conformation; Open Reading Frames; PATOGENICIDAD; Phenotype; Phytopathology. Animal pests. Plant and forest protection; PLASMIDE; PLASMIDIOS; Plasmids - genetics; POUVOIR PATHOGENE; PROTEASAS; PROTEASE; Repetitive Sequences, Nucleic Acid; RNA, Bacterial - chemistry; RNA, Bacterial - genetics; SECUENCIA NUCLEOTIDICA; Sequence Deletion; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; SEQUENCE NUCLEOTIDIQUE; Systematics. Structure, properties and multiplication. Genetics; Virulence - genetics; Plant pathogen; Nucleotide sequence; Virulence; Sequence alignment; Secondary structure; Strain; Plasmid; Pathogenicity; Messenger RNA; Clavibacter michiganensis; Bacteria; Actinomycetes; Comparative study; Aminoacid sequence; Structural analysis
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.1997.10.2.195

The tomato pathogen Clavibacter michiganensis subsp. michiganensis NCPPB382, causing bacterial wilt and canker, harbors two plasmids, pCM1 (27.5 kb) and pCM2 (72 kb), carrying genes involved in virulence. The region of plasmid pCM2 encoding the pathogenicity locus pat-1 was mapped by deletion analysis and complementation studies to a 1.5-kb BglII/SmaI DNA fragment. Introduction of the pat-1 region into endophytic, plasmid-free isolates of C. michiganensis subsp. michiganensis converted these bacteria into virulent pathogens. Based on the nucleotide sequence of the pas-1 region, an open reading frame (ORF1) can be predicted, coding for a protein of 280 amino acids and 29.7 kDa with homology to serine proteases. Introduction of a frame-shift mutation in ORF1 leads to a loss of the pathogenic phenotype. Northern (RNA) hybridizations identified an 1.5-knt transcript of the pat-1 structural gene. The site of transcription initiation was mapped by primer extension and a typical -10/-35 region was located with significant homology to the consensus Escherichia coli sigma 70 and Bacillus subtilis sigma 43 promoters. Downstream of the pat-1 structural gene, a peculiar repetitive sequence motif (pat-1rep) is located, consisting of 20 direct tandem repeats preceded by a run of 14 guanosine residues. DNA sequences homologous to pat-1rep were isolated and characterized from four virulent C. michiganensis subsp. michiganensis strains exhibiting a high extent of structural conservation. The deletion of this repetitive sequence reduced virulence significantly but did not lead to a complete loss of the virulence phenotype