Original Article

Biosynthesis of 3′-Deoxy-carbamoylkanamycin C in a Streptomyces tenebrarius Mutant Strain by tacB Gene Disruption

Yonghong Yu, Xifan Hou, Xianpu Ni, Huanzhang Xia

Received: July 11, 2007 / Accepted: February 1, 2008
© Japan Antibiotics Research Association

Abstract Streptomyces tenebrarius H6 mainly produces three kinds of antibiotics: apramycin, carbamoyltobramycin and some carbamoylkanamycin B. In our present study, a dehydrogenase gene tacB in the tobramycin biosynthetic gene cluster was disrupted by in-frame deletion. The result of TLC bio-autograph analysis demonstrated the disruption mutant strain produced apramycin and a new antibiotic. The new antibiotic was identified as 3′-deoxy-carbamoylkanamycin C by MS and NMR analysis after isolation and purification. The disruption mutant was restored to produce carbamoyltobramycin in a complementation experiment by the intact tacB gene. Our studies suggested that the tacB gene encodes a 6′-dehydrogenase, which reduces the 6′-hydroxyl group of paromamine to a keto group, thus facilitating the transfer of an aminogroup to form neamine. This study is the first report on the generation of a tobramycin derivative by gene engineering, and will contribute to clarify the complete biosynthetic pathway of tobramycin.

Keywords Streptomyces tenebrarius, in-frame deletion, complementation, 6′-dehydrogenase, 3′-deoxy-carbamoylkanamycin C

H. Xia (Corresponding author), Y. Yu, X. Hou, X. Ni: The School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, China, E-mail: xiahz612@sina.com