Suppression of SOS repair in E. coli: possible mechanism of antimutagenicity and protective effects of common vegetables

Abstract

This study aims to understand variations in antimutagenic potential of vegetables, as observed in reduction of UV-induced mutation (Rif^S→Rif^R) in Escherichia coli cells. On further investigation, the juice of vegetables [eggplant (small-violet), pepper (hot Arbol), bean (French), and tomato] was found to suppress mutagenic SOS response as measured by cell filamentation, LexA degradation, and induction of defective prophage as per their antimutagenic potential. Cell filamentation which was observed in 25 and 60% of the UV- and gamma-induced cells, reduced to 2–8%, and 3–16%, respectively in the presence of the vegetable juice; moreover, LexA was also not significantly affected. Phage induction frequency reduced upto 76% compared to control UV-exposed cells. The antimutagenic effect was found to be partially dependent on recB, ruvB gene functions, and was independent of uvrA function. Phenolic compounds were found to be the major contributors to the observed antimutagenicity.

• Antimutagenic potential
• cell filamentation
• LexA cleavage
• SIVET
• vegetables

Acknowledgements

The authors acknowledge Keio Collection, Japan for E. coli knockout strains provided to our institute, Bhabha Atomic Research Centre, Mumbai, India and S. H. Mangoli, our institutional colleague for sharing us these strains. We also thank Prof. M. Z. Humayun, UMDNJ, USA for gifting E. coli MG1655 and SG 104 strains.

Supplementary material available online Supplementary Figure S1