Biosynthesis of the Carbamoylated D‐Gulosamine Moiety of Streptothricins: Involvement of a Guanidino‐N‐glycosyltransferase and an N‐Acetyl‐D‐gulosamine Deacetylase |
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| Authors: | Dr Zhengyan Guo Dr Jine Li Dr Hua Qin Dr Min Wang Dr Xun Lv Prof Xuebing Li Prof Yihua Chen |
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| Institution: | 1. State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101 (China);2. CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101 (China) |
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| Abstract: | Streptothricins (STNs) are atypical aminoglycosides containing a rare carbamoylated D ‐gulosamine (D ‐GulN) moiety, and the antimicrobial activity of STNs has been exploited for crop protection. Herein, the biosynthetic pathway of the carbamoylated D ‐GulN moiety was delineated. An N‐acetyl‐D ‐galactosamine is first attached to the streptolidine lactam by the glycosyltransferse StnG and then epimerized to N‐acetyl‐D ‐gulosamine by the putative epimerase StnJ. After carbamoylation by the carbamoyltransferase StnQ, N‐acetyl‐D ‐GulN is deacetylated by StnI to furnish the carbamoylated D ‐GulN moiety. In vitro studies characterized two novel enzymes: StnG is an unprecedented GT‐A fold N‐glycosyltransferase that glycosylates the imine nitrogen atom of guanidine, and StnI is the first reported N‐acetyl‐D ‐GulN deacetylase. |
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| Keywords: | aminoglycoside biosynthesis deacetylation D‐gulosamine glycosylation |
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