Streptomyces scabies 87-22 possesses a functional tomatinase.

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.

• Authors: Ryan F Seipke, Rosemary Loria
• Journal: Journal of bacteriology (J Bacteriol) Vol. 190 Issue 23 Pg. 7684-92 (Dec 2008) ISSN: 1098-5530 [Electronic] United States
• PMID: 18835993 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

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

Topics

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