Research Article: De Novo RNA Sequencing and Transcriptome Analysis of Monascus purpureus and Analysis of Key Genes Involved in Monacolin K Biosynthesis

Date Published: January 23, 2017

Publisher: Public Library of Science

Author(s): Chan Zhang, Jian Liang, Le Yang, Baoguo Sun, Chengtao Wang, Maoteng Li.

http://doi.org/10.1371/journal.pone.0170149

Abstract

Monascus purpureus is an important medicinal and edible microbial resource. To facilitate biological, biochemical, and molecular research on medicinal components of M. purpureus, we investigated the M. purpureus transcriptome by RNA sequencing (RNA-seq). An RNA-seq library was created using RNA extracted from a mixed sample of M. purpureus expressing different levels of monacolin K output. In total 29,713 unigenes were assembled from more than 60 million high-quality short reads. A BLAST search revealed hits for 21,331 unigenes in at least one of the protein or nucleotide databases used in this study. The 22,365 unigenes were categorized into 48 functional groups based on Gene Ontology classification. Owing to the economic and medicinal importance of M. purpureus, most studies on this organism have focused on the pharmacological activity of chemical components and the molecular function of genes involved in their biogenesis. In this study, we performed quantitative real-time PCR to detect the expression of genes related to monacolin K (mokA-mokI) at different phases (2, 5, 8, and 12 days) of M. purpureus M1 and M1-36. Our study found that mokF modulates monacolin K biogenesis in M. purpureus. Nine genes were suggested to be associated with the monacolin K biosynthesis. Studies on these genes could provide useful information on secondary metabolic processes in M. purpureus. These results indicate a detailed resource through genetic engineering of monacolin K biosynthesis in M. purpureus and related species.

Partial Text

Monascus purpureus is a mold that is an important medicinal and edible resource. Products fermented with M. purpureus have been used for thousands of years in China and other Southeast Asian countries. M. purpureus metabolic components include bioactive compounds [1–3] such as pigments [4], monacolin K [5–7], citrinin [8], aminobutyric acid [9], ergosterol, toxins and other metabolites [10,11], hydrolytic enzymes [12] that are involved in a wide range of activities [13,14] and are used as ingredients in food coloring [15,16], wine and pharmaceuticals.

In this study, we obtained the transcriptome information of M. purpureus, including functional annotation and classification, which could provide insight into the role of intracellular metabolic pathways [54]. In this study, we examined the functions of M. purpureus unigenes by BLAST searches against various databases [55]. Illumina HiSeq 2000 sequencing generated 60 million high-quality short reads, which were assembled into 29,713 assembled unigenes in M. purpureus. In summary, 122,599 unigenes showed a match with the GO annotation. Meanwhile, biosynthetic pathways involving some of these unigenes have been identified. These results contribute to existing sequence resources of M. purpureus and will be useful for studies on the biosynthesis of secondary metabolites such as aminoacyl-tRNA, nitrogen metabolism, and terpenoids in M. purpureus.

 

Source:

http://doi.org/10.1371/journal.pone.0170149

 

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