Genome-wide response on phytosterol in 9-hydroxyandrostenedione-producing strain of Mycobacterium sp. VKM Ac-1817D

Abstract

Background Aerobic side chain degradation of phytosterols by actinobacteria is the basis for the industrial production of androstane steroids which are the starting materials for the synthesis of steroid hormones. A native strain of Mycobacterium sp. VKM Ac-1817D effectively produces 9α-hydroxyandrost-4-ene-3,17-dione (9-OH-AD) from phytosterol, but also is capable of slow steroid core degradation. However, the set of the genes with products that are involved in phytosterol oxidation, their organisation and regulation remain poorly understood. Results High-throughput sequencing of the global transcriptomes of the Mycobacterium sp. VKM Ac-1817D cultures grown with or without phytosterol was carried out. In the presence of phytosterol, the expression of 260 genes including those related to steroid catabolism pathways significantly increased. Two of the five genes encoding the oxygenase unit of 3-ketosteroid-9α-hydroxylase ( kshA ) were highly up-regulated in response to phytosterol (55- and 25-fold, respectively) as well as one of the two genes encoding its reductase subunit ( kshB ) (40-fold). Only one of the five putative genes encoding 3-ketosteroid-∆ 1 -dehydrogenase (KstD_1) was up-regulated in the presence of phytosterol (61-fold), but several substitutions in the conservative positions of its product were revealed. Among the genes over-expressed in the presence of phytosterol, several dozen genes did not possess binding sites for the known regulatory factors of steroid catabolism. In the promoter regions of these genes, a regularly occurring palindromic motif was revealed. The orthologue of TetR-family transcription regulator gene Rv0767c of M. tuberculosis was identified in Mycobacterium sp. VKM Ac-1817D as G155_05115 . Conclusions High expression levels of the genes related to the sterol side chain degradation and steroid 9α-hydroxylation in combination with possible defects in KstD_1 may contribute to effective 9α-hydroxyandrost-4-ene-3,17-dione accumulation from phytosterol provided by this biotechnologically relevant strain. The TetR-family transcription regulator gene G155_05115 presumably associated with the regulation of steroid catabolism. The results are of significance for the improvement of biocatalytic features of the microbial strains for the steroid industry. Electronic supplementary material The online version of this article (10.1186/s12896-019-0533-7) contains supplementary material, which is available to authorized users.

Different genome-wide transcriptome responses of Nocardioides simplex VKM Ac-2033D to phytosterol and cortisone 21-acetate

“…Acyl-CoA synthetase FadD19 catalyzes the formation of the cholestanoate CoA-thioester [ 13 ] that is further oxidized to C-17-ketosteroids by three successive cycles of β-oxidation [ 4 , 14 ]. 9α-Hydroxylase (KshAB, consisting of KshA and KshB subunits) and 3-ketosteroid-∆ 1 -dehydrogenase (KstD) [ 15 , 16 ] are well-known as key enzymes of steroid core degradation whose cooperative action provides the ring B opening (Fig. 1 ).…”

Whole-genome and enzymatic analyses of an androstenedione-producing Mycobacterium strain with residual phytosterol-degrading pathways

“…The global transcriptome analysis of Mycobacterium sp . VKM Ac-1817D, a strain producing 9OH-AD and genetically close to NRRL B-3805, revealed that phytosterols stimulated the increased expression of 260 genes, including those related to steroid catabolism in mycobacteria [ 19 ]. Other bacteria contain either a similar steroid degradation pathway, e.g., in Pseudomonas sp.…”

Genome-Wide Transcriptome Profiling Provides Insight on Cholesterol and Lithocholate Degradation Mechanisms in Nocardioides simplex VKM Ac-2033D

“…The cells taken in the exponential growth phase (16 h) were harvested by centrifuge at 8000× g for 10 min. mRNA was isolated as described earlier [ 27 ]. The resulting mixture was treated with a Turbo DNA-free kit (Thermo Fisher Scientific, Whaltham, MA, USA).…”