CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum

• Published in: Molecular plant pathology Vol. 13; no. 1; pp. 58 - 71
• Main Authors: KERSEY, CALEB M., AGYEMANG, PAUL A., DUMENYO, C. KORSI
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2012; Blackwell
• Subjects: Amino Acid Sequence; Apium graveolens - drug effects; Apium graveolens - microbiology; Bacterial plant pathogens; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Cellulase; Cobalt; Cobalt - toxicity; Data processing; Daucus carota - drug effects; Daucus carota - microbiology; DNA; Environmental factors; Enzymes - biosynthesis; Enzymes - chemistry; Enzymes - genetics; Erwinia carotovora; Extracellular enzymes; Extracellular Space - drug effects; Extracellular Space - enzymology; Extrachromosomal Inheritance - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial - drug effects; Genetic Complementation Test; Host plants; Magnesium; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Molecular Sequence Data; Motility; Mutant Proteins - chemistry; Mutant Proteins - isolation & purification; Mutant Proteins - metabolism; Mutation - genetics; Nickel; Original; Pathogenicity; Pathogens; Pectate lyase; Pectobacterium; Pectobacterium carotovorum - enzymology; Pectobacterium carotovorum - genetics; Pectobacterium carotovorum - growth & development; Pectobacterium carotovorum - pathogenicity; Peptide Hydrolases - genetics; Peptide Hydrolases - metabolism; Phenotype; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - genetics; Plant Diseases - microbiology; Polygalacturonase; Polysaccharide-Lyases - genetics; Polysaccharide-Lyases - metabolism; Proteinase; Salmonella enterica; Sequence Alignment; Soft rot; Virulence; Virulence - drug effects; Erwinia carotovora; Plant pathogen; Enzyme; Virulence; Bacteria; Nickel; Magnesium; Cobalt; Extracellular; Enterobacteriaceae
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/j.1364-3703.2011.00726.x

SUMMARY Pectobacterium carotovorum (formerly Erwinia carotovora ssp. carotovora) is a phytopathogenic bacterium that causes soft rot disease, characterized by water‐soaked soft decay, resulting from the action of cell wall‐degrading exoenzymes secreted by the pathogen. Virulence in soft rot bacteria is regulated by environmental factors, host and bacterial chemical signals, and a network of global and gene‐specific bacterial regulators. We isolated a mini‐Tn5 mutant of P. carotovorum that is reduced in the production of extracellular pectate lyase, protease, polygalacturonase and cellulase. The mutant is also decreased in virulence as it macerates less host tissues than its parent and is severely impaired in multiplication in planta. The inactivated gene responsible for the reduced virulent phenotype was identified as corA. CorA, a magnesium/nickel/cobalt membrane transporter, is the primary magnesium transporter for many bacteria. Compared with the parent, the CorA‐ mutant is cobalt resistant. The mutant phenotype was confirmed in parental strain P. carotovorum by marker exchange inactivation of corA. A functional corA+ DNA from P. carotovorum restored exoenzyme production and pathogenicity to the mutants. The P. carotovorum corA+ clone also restored motility and cobalt sensitivity to a CorA‐ mutant of Salmonella enterica. These data indicate that CorA is required for exoenzyme production and virulence in P. carotovorum.