文献类型：期刊文献

英文题名：Unraveling and engineering the production of 23,24-bisnorcholenic steroids in sterol metabolism

作者：Xu, Li-Qin[1];Liu, Yong-Jun[1];Yao, Kang[1];Liu, Hao-Hao[1];Tao, Xin-Yi[1];Wang, Feng-Qing[1];Wei, Dong-Zhi[1]

机构：[1]E China Univ Sci & Technol, Newworld Inst Biotechnol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China

年份：2016

卷号：6

外文期刊名：SCIENTIFIC REPORTS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000370518400001)】；

基金：We thank T. Parish (Department of Infectious and Tropical Diseases, United Kingdom) for providing plasmids, p2NIL and pGOAL19, and W. R. Jacobs, Jr. (Howard Hughes Medical Institute) for providing plasmid pMV261. This research was financially supported by the National Natural Science Foundation of China (No. 31370080), the National Special Fund for State Key Laboratory of Bioreactor Engineering, the National Basic Research Program of China (973, Program No. 2012CB721003) and the National Major Science and Technology Projects of China (No. 2012ZX09304009).

语种：英文

摘要：The catabolism of sterols in mycobacteria is highly important due to its close relevance in the pathogenesis of pathogenic strains and the biotechnological applications of nonpathogenic strains for steroid synthesis. However, some key metabolic steps remain unknown. In this study, the hsd4A gene from Mycobacterium neoaurum ATCC 25795 was investigated. The encoded protein, Hsd4A, was characterized as a dual-function enzyme, with both 17 beta-hydroxysteroid dehydrogenase and beta-hydroxyacyl-CoA dehydrogenase activities in vitro. Using a kshAs-null strain of M. neoaurum ATCC 25795 (NwIB-XII) as a model, Hsd4A was further confirmed to exert dual-function in sterol catabolism in vivo. The deletion of hsd4A in NwIB-XII resulted in the production of 23,24-bisnorcholenic steroids (HBCs), indicating that hsd4A plays a key role in sterol side-chain degradation. Therefore, two competing pathways, the AD and HBC pathways, were proposed for the side-chain degradation. The proposed HBC pathway has great value in illustrating the production mechanism of HBCs in sterol catabolism and in developing HBCs producing strains for industrial application via metabolic engineering. Through the combined modification of hsd4A and other genes, three HBCs producing strains were constructed that resulted in promising productivities of 0.127, 0.109 and 0.074 g/ l/ h, respectively.