Browsing by Author "Wang, Wei-Yi"

Now showing 1 - 2 of 2

Exploring the Distribution of Citrinin Biosynthesis Related Genes among Monascus Species
(2008-12-24)
Chen, Yi-Pei
;
Tseng, Ching-Ping
;
Chien, I-Ling
;
Wang, Wei-Yi
;
Liaw, Li-Ling
Citrinin, a hepato-nephrotoxic compound to humans, can be produced by the food fermentation microorganisms Monascus spp. In this study, we investigated the distribution of mycotoxin citrinin biosynthesis genes in 18 Monascus strains. The results show that the acyl-transferase and keto-synthase domains of the pksCT gene encoding citrinin polyketide synthase were found in Monascus purpureus, Monascus kaoliang, and Monascus sanguineus. Furthermore, the ctnA gene, a major activator for citrinin biosynthesis, was found in M. purpureus and U kaoliang, but was absent in M. sanguineus. The orf3 gene encoding oxygenase, located between pksCT and ctnA, was also present in M. purpureus and M. kaoliang. The pksCT gene was highly conserved in M. purpureus, U kaoliang, and M. sanguineus, while the ctnA and orf3 genes were shown to be highly homologous in M. purpureus and M. kaoliang. In contrast, the PCR and Southern blot analyses suggest that pksCT, ctnA, and orf3 were absent or significantly different in Monascus pilosus, Monascus ruber, Monascus barkeri, Monascus floridanus, Monascus lunisporas, and Monascus pallens. A citrinin-producing phenotype was detected only in M. purpureus and M., kaoliang using high performance liquid chromatography (HPLC). These results clearly indicate that the highly conserved citrinin gene cluster in M. purpureus and U kaoliang carry out citrinin biosynthesis. In addition, according to the phylogenetic subgroups established with the beta-tubulin gene, the citrinin gene cluster can group the species of Monascus.
Identification of the mokH Gene Encoding Transcription Factor for the Upregulation of Monacolin K Biosynthesis in Monascus pilosus
(2010-01-13)
Chen, Yi-Pei
;
Yuan, Gwo-Fang
;
Hsieh, Sung-Yuan
;
Lin, Yu-Shan
;
Wang, Wei-Yi
Monacolin K is a secondary metabolite synthesized by polyketide synthases (PKS) from Monascus. The monacolin K biosynthetic gene cluster, mokA-mokI, has been characterized in Monascus pilosus. The mokH gene encoding Zn(II)2Cys6 binuclear DNA binding protein is assumed to be an activator for monacolin K production. In this study, the mokH gene was cloned and driven by the glyceraldehyde-3-phosphate dehydrogenase (gpd) promoter for overexpression in M. pilosus. The transformants containing an extra copy of the mokH gene were obtained and verified by PCR and Southern hybridization. The transcripts of mokH in the transformants were expressed significantly higher than those of the wild-type strain. The transformants were stably inherited through the next generation, as determined by observation of the enhanced green fluorescent protein (EGFP). The transformant T-mokH1 also showed a 1.7-fold higher production of monacolin K than the wild-type strain in a time course analysis. Analysis of the RT-PCR products demonstrated that the monacolin K biosynthetic genes in the transformant were expressed to a greater extent than those in the wildtype strain. These results indicated that mokH upregulated the transcription of monacolin K biosynthetic genes and increased monacolin K production.