Novel polyoxins generated by heterologously expressing polyoxin biosynthetic gene cluster in the <it>sanN</it> inactivated mutant of <it>Streptomyces ansochromogenes</it>

• Main Authors: Li Jine, Li Lei, Feng Chi, Chen Yihua, Tan Huarong
• Format: Article
• Language: English
• Published: BMC 2012-10-01
• Series: Microbial Cell Factories
• Subjects: Polyoxin; Gene cluster; Heterologous expression; <it>S. ansochromogenes</it>
• Online Access: http://www.microbialcellfactories.com/content/11/1/135

<p>Abstract</p> <p>Background</p> <p>Polyoxins are potent inhibitors of chitin synthetases in fungi and insects. The gene cluster responsible for biosynthesis of polyoxins has been cloned and sequenced from <it>Streptomyces cacaoi</it> and tens of polyoxin analogs have been identified already.</p> <p>Results</p> <p>The polyoxin biosynthetic gene cluster from <it>Streptomyces cacaoi</it> was heterologously expressed in the <it>sanN</it> inactivated mutant of <it>Streptomyces ansochromogenes</it> as a nikkomycin producer. Besides hybrid antibiotics (polynik A and polyoxin N) and some known polyoxins, two novel polyoxin analogs were accumulated. One of them is polyoxin P that has 5-aminohexuronic acid with <it>N</it>-glycosidically bound thymine as the nucleoside moiety and dehydroxyl-carbamoylpolyoxic acid as the peptidyl moiety. The other analog is polyoxin O that contains 5-aminohexuronic acid bound thymine as the nucleoside moiety, but recruits polyoximic acid as the sole peptidyl moiety. Bioassay against phytopathogenic fungi showed that polyoxin P displayed comparatively strong inhibitory activity, whereas the inhibitory activity of polyoxin O was weak under the same testing conditions.</p> <p>Conclusion</p> <p>Two novel polyoxin analogs (polyoxin P and O) were generated by the heterologous expression of polyoxin biosynthetic gene cluster in the <it>sanN</it> inactivated mutant of <it>Streptomyces ansochromogenes</it>. Polyoxin P showed potent antifungal activity,while the activity of polyoxin O was weak. The strategy presented here may be available for other antibiotics producers.</p>