Lobastova Tatyana, Fokina Victoria, Tarlachkov Sergey, Shutov Andrey, Bragin Eugeny, Kazantsev Alexey, Donova Marina
G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Pr. Nauki 5, 142290 Pushchino, Russia.
Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia.
Microorganisms. 2021 Dec 10;9(12):2554. doi: 10.3390/microorganisms9122554.
The application of thermophilic microorganisms opens new prospects in steroid biotechnology, but little is known to date on steroid catabolism by thermophilic strains. The thermophilic strain VKM Ac-666 has been shown to convert various steroids and to fully degrade cholesterol. Cholest-4-en-3-one, cholesta-1,4-dien-3-one, 26-hydroxycholest-4-en-3-one, 3-oxo-cholest-4-en-26-oic acid, 3-oxo-cholesta-1,4-dien-26-oic acid, 26-hydroxycholesterol, 3β-hydroxy-cholest-5-en-26-oic acid were identified as intermediates in cholesterol oxidation. The structures were confirmed by H and C-NMR analyses. Aliphatic side chain hydroxylation at C26 and the A-ring modification at C3, which are putatively catalyzed by cytochrome P450 monooxygenase CYP125 and cholesterol oxidase, respectively, occur simultaneously in the strain and are followed by cascade reactions of aliphatic sidechain degradation and steroid core destruction via the known 9(10)--pathway. The genes putatively related to the sterol and bile acid degradation pathways form three major clusters in the genome. The sets of the genes include the orthologs of those involved in steroid catabolism in H37Rv and RHA1 and related actinobacteria. Bioinformatics analysis of 52 publicly available genomes of thermophilic bacteria revealed only seven candidate strains that possess the key genes related to the 9(10)- pathway of steroid degradation, thus demonstrating that the ability to degrade steroids is not widespread among thermophilic bacteria.
嗜热微生物的应用为甾体生物技术开辟了新前景，但迄今为止，关于嗜热菌株对甾体的分解代谢知之甚少。嗜热菌株VKM Ac-666已被证明能转化多种甾体并完全降解胆固醇。胆甾-4-烯-3-酮、胆甾-1,4-二烯-3-酮、26-羟基胆甾-4-烯-3-酮、3-氧代胆甾-4-烯-26-酸、3-氧代胆甾-1,4-二烯-26-酸、26-羟基胆固醇、3β-羟基胆甾-5-烯-26-酸被鉴定为胆固醇氧化的中间产物。其结构通过氢核磁共振和碳核磁共振分析得以确认。该菌株中，分别由细胞色素P450单加氧酶CYP125和胆固醇氧化酶催化的C26位脂肪族侧链羟基化和C3位A环修饰同时发生，随后通过已知的9(10)-途径进行脂肪族侧链降解和甾体核心破坏的级联反应。推测与甾醇和胆汁酸降解途径相关的基因在基因组中形成三个主要簇。这些基因集包括与H37Rv、RHA1及相关放线菌中甾体分解代谢相关的直系同源基因。对52个公开可用的嗜热细菌基因组进行生物信息学分析，仅发现7个候选菌株拥有与甾体降解9(10)-途径相关的关键基因，这表明降解甾体的能力在嗜热细菌中并不普遍。
