Streptomyces Scabies 87-22 Possesses a Functional Tomatinase

J Bacteriol. 2008 Dec;190(23):7684-92. doi: 10.1128/JB.01010-08. Epub 2008 Oct 3.

Abstract

The actinomycete Streptomyces scabies 87-22 is the causal agent of common scab, an economically important disease of potato and taproot crops. Sequencing of the S. scabies 87-22 genome revealed the presence of a gene with high homology to the gene encoding the alpha-tomatine-detoxifying enzyme tomatinase found in fungal tomato pathogens. The tomA gene from S. scabies 87-22 was cotranscribed with a putative family 1 glycosyl hydrolase gene, and purified TomA protein was active only on alpha-tomatine and not potato glycoalkaloids or xylans. Tomatinase-null mutants were more sensitive to alpha-tomatine than the wild-type strain in a disk diffusion assay. Interestingly, tomatine affected only aerial mycelium and not vegetative mycelium, suggesting that the target(s) of alpha-tomatine is not present during vegetative growth. Severities of disease for tomato seedlings affected by S. scabies 87-22 wild-type and DeltatomA1 strains were indistinguishable, suggesting that tomatinase is not important in pathogenicity on tomato plants. However, conservation of tomA on a pathogenicity island in S. acidiscabies and S. turgidiscabies suggests a role in plant-microbe interaction.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism*
  • Gene Expression Regulation, Bacterial / physiology
  • Glycoside Hydrolases / genetics*
  • Glycoside Hydrolases / metabolism*
  • Molecular Sequence Data
  • Molecular Structure
  • Streptomyces / enzymology*
  • Tomatine / analogs & derivatives
  • Tomatine / chemistry
  • Tomatine / metabolism

Substances

  • Bacterial Proteins
  • tomatidine
  • Tomatine
  • Glycoside Hydrolases
  • tomatinase