题目: Biochemical and Structural Insights into the Aminotransferase CrmG in Caerulomycin Biosynthesis

作者: Yiguang Zhu+, Jinxin Xu+, Xiangui Mei+, Zhan Feng, Liping Zhang, Qingbo Zhang, Guangtao Zhang, Weiming Zhu*, Jinsong Liu*, Changsheng Zhang*.

刊物: ACS Chemical Biology

年卷期页: 2016,11(4):943-952

摘要: Caerulomycin A (CRM A 1) belongs to a family of natural products containing a 2,2′-bipyridyl ring core structure and is currently under development as a potent novel immunosuppressive agent. Herein, we report the functional characterization, kinetic analysis, substrate specificity, and structure insights of an aminotransferase CrmG in 1 biosynthesis. The aminotransferase CrmG was confirmed to catalyze a key transamination reaction to convert an aldehyde group to an amino group in the 1 biosynthetic pathway, preferring L-glutamate and L-glutamine as the amino donor substrates. The crystal structures of CrmG in complex with the cofactor 5′-pyridoxal phosphate (PLP) or 5′-pyridoxamine phosphate (PMP) or the acceptor substrate were determined to adopt a canonical fold-type I of PLP-dependent enzymes with a unique small additional domain. The structure guided site-directed mutagenesis identified key amino acid residues for substrate binding and catalytic activities, thus providing insights into the transamination mechanism of CrmG.