文献类型：期刊文献

英文题名：Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons

作者：Zhao, Yun-Qiu[1];Liu, Yong-Jun[1];Song, Lu[1];Yu, Dingyan[1];Liu, Kun[1];Liu, Ke[1];Gao, Bei[1];Tao, Xin-Yi[1];Xiong, Liang-Bin[1,2];Wang, Feng-Qing[1];Wei, Dong-Zhi[1]

机构：[1]East China Univ Sci & Technol, Newworld Inst Biotechnol, State Key Lab Bioreactor Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China;[2]Shanghai Univ Med & Hlth Sci, Shanghai Key Lab Mol Imaging, Shanghai 201318, Peoples R China

年份：2023

卷号：16

期号：1

外文期刊名：BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS

收录：;EI(收录号：20233314533391);WOS:【SCI-EXPANDED(收录号:WOS:001039773500001)】；

语种：英文

外文关键词：Mycolicibacteria; HBC sub-pathway; atf1; HBC operon; C-22 steroid; 4-HBC

摘要：BackgroundHarnessing engineered Mycolicibacteria to convert cheap phytosterols into valuable steroid synthons is a basic way in the industry for the production of steroid hormones. Thus, C-19 and C-22 steroids are the two main types of commercial synthons and the products of C17 side chain degradation of phytosterols. During the conversion process of sterols, C-19 and C-22 steroids are often produced together, although one may be the main product and the other a minor byproduct. This is a major drawback of the engineered Mycolicibacteria for industrial application, which could be attributed to the co-existence of androstene-4-ene-3,17-dione (AD) and 22-hydroxy-23,24-bisnorchol-4-ene-3-one (HBC) sub-pathways in the degradation of the sterol C17 side chain. Since the key mechanism underlying the HBC sub-pathway has not yet been clarified, the above shortcoming has not been resolved so far.ResultsThe key gene involved in the putative HBC sub-pathway was excavated from the genome of M. neoaurum by comparative genomic analysis. Interestingly, an aldolase- encoding gene, atf1, was identified to be responsible for the first reaction of the HBC sub-pathway, and it exists as a conserved operon along with a DUF35-type gene chsH4, a reductase gene chsE6, and a transcriptional regulation gene kstR3 in the genome. Subsequently, atf1 and chsH4 were identified as the key genes involved in the HBC sub-pathway. Therefore, an updated strategy was proposed to develop engineered C-19 or C-22 steroid-producing strains by simultaneously modifying the AD and HBC sub-pathways. Taking the development of 4-HBC and 9-OHAD-producing strains as examples, the improved 4-HBC-producing strain achieved a 20.7 g/L production titer with a 92.5% molar yield and a 56.4% reduction in byproducts, and the improved 9-OHAD producing strain achieved a 19.87 g/L production titer with a 94.6% molar yield and a 43.7% reduction in byproduct production.ConclusionsThe excellent performances of these strains demonstrated that the primary operon involved in the HBC sub-pathway improves the industrial strains in the conversion of phytosterols to steroid synthons.