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Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons
BACKGROUND: Harnessing 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 degrada...
Autores principales: | , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10398937/ https://www.ncbi.nlm.nih.gov/pubmed/37533054 http://dx.doi.org/10.1186/s13068-023-02376-2 |
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author | Zhao, Yun-Qiu Liu, Yong-Jun Song, Lu Yu, Dingyan Liu, Kun Liu, Ke Gao, Bei Tao, Xin-Yi Xiong, Liang-Bin Wang, Feng-Qing Wei, Dong-Zhi |
author_facet | Zhao, Yun-Qiu Liu, Yong-Jun Song, Lu Yu, Dingyan Liu, Kun Liu, Ke Gao, Bei Tao, Xin-Yi Xiong, Liang-Bin Wang, Feng-Qing Wei, Dong-Zhi |
author_sort | Zhao, Yun-Qiu |
collection | PubMed |
description | BACKGROUND: Harnessing 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. RESULTS: The 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. CONCLUSIONS: The 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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-023-02376-2. |
format | Online Article Text |
id | pubmed-10398937 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-103989372023-08-04 Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons Zhao, Yun-Qiu Liu, Yong-Jun Song, Lu Yu, Dingyan Liu, Kun Liu, Ke Gao, Bei Tao, Xin-Yi Xiong, Liang-Bin Wang, Feng-Qing Wei, Dong-Zhi Biotechnol Biofuels Bioprod Research BACKGROUND: Harnessing 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. RESULTS: The 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. CONCLUSIONS: The 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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-023-02376-2. BioMed Central 2023-08-02 /pmc/articles/PMC10398937/ /pubmed/37533054 http://dx.doi.org/10.1186/s13068-023-02376-2 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
spellingShingle | Research Zhao, Yun-Qiu Liu, Yong-Jun Song, Lu Yu, Dingyan Liu, Kun Liu, Ke Gao, Bei Tao, Xin-Yi Xiong, Liang-Bin Wang, Feng-Qing Wei, Dong-Zhi Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title | Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title_full | Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title_fullStr | Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title_full_unstemmed | Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title_short | Unravelling and engineering an operon involved in the side-chain degradation of sterols in Mycolicibacterium neoaurum for the production of steroid synthons |
title_sort | unravelling and engineering an operon involved in the side-chain degradation of sterols in mycolicibacterium neoaurum for the production of steroid synthons |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10398937/ https://www.ncbi.nlm.nih.gov/pubmed/37533054 http://dx.doi.org/10.1186/s13068-023-02376-2 |
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