This study aimed to clone and explore the differential expression of the C-24 sterol methyltransferase gene (ERG6), which is the key gene involved in the ergosterol biosynthesis pathway of S. baumii, to characterize the role of ERG6 in ergosterol biosynthesis pathway and provide a theoretical basis for obtaining the ergosterol high-yielding strains by biotechnology.

The full-length cDNA of ERG6 was cloned by PCR amplification and subsequently sequenced, and the prokaryotic expression of ERG6 was detected by SDS-PAGE. The sequence of the ERG6 promoter was cloned and analyzed by bioinformatics software. qRT-PCR was used to analyze the transcriptional level of ERG6 in S. baumii at different developmental stages. The content of ergosterol was determined by the spectrophotometer.

The full-length cDNA of ERG6 was successfully cloned. SDS-PAGE showed that the target ERG6 protein could be successfully expressed in the prokaryotic system, which expression was significantly higher than other proteins. At the same time, it was found that the protein expression increased gradually with the increase of induction time. Bioinformatics analyzed and found the gene sequence of ERG6 was 996 bp, encoding 331 amino acids, which had 42 potential phosphorylation sites and no signal peptides as well as transmembrane structures. The results of promoter sequence analysis showed that the ERG6 promoter had a core promoter region and 4 transcription factors that may be involved in its expression regulation. In addition to the typical promoter action elements, it also had a variety of response elements such as methyl jasmonate, gibberellin and abscisic acid. The results of fluorescence quantification and ergosterol content determination showed that the expression of ERG6 was positively correlated with the changing trend of the ergosterol content at different development stages.

ERG6 plays a positive regulatory role in ergosterol biosynthesis, which lays a foundation for the cultivation of ergosterol high-yielding strains in S. baumii.