Molecular cloning and characterization of an ML-236B (compactin) biosynthetic gene cluster in Penicillium citrinum

Abstract

Cloning of genes encoding polyketide synthases (PKSs) has allowed us to identify a gene cluster for ML-236B biosynthesis in Penicillium citrinum. Like lovastatin, which is produced by Aspergillus terreus, ML-236B (compactin) inhibits the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Genomic sequencing and Northern analysis showed that nine predicted genes for ML-236B biosynthesis were located within a 38-kb region and were transcribed when ML-236B was produced. The predicted amino acid sequences encoded by these nine genes, designated mlcA- mlcH and mlcR, were similar to those encoded by the genes for lovastatin synthesis, and were therefore assumed to be involved either directly or indirectly in ML-236B biosynthesis. Targeted disruption experiments provided evidence that two PKS genes in the cluster, mlcA and mlcB, are required for the biosynthesis of the nonaketide and the diketide moieties, respectively, of ML-236B, suggesting that the gene cluster as a whole is responsible for ML-236B biosynthesis in P. citrinum. Bioconversion of some of the predicted intermediates by an mlcA-disrupted mutant was also investigated in order to analyze the ML-236B biosynthetic pathway. The molecular organization of the gene cluster and proposed functions for the ML-236B biosynthetic genes in P. citrinum are described.

Crystal structure and biochemical studies of the trans-acting polyketide enoyl reductase LovC from lovastatin biosynthesis

“…1A; tetra-, penta-, and heptaketides). Similar trans-acting ERs have also been reported in other fungi such as MokE in Monascus pilosus (8), MlcG in Penicillium citrinum (9), ApdC in Aspergilus nidulans (10-12), cytochalasans (12,13), and tenellin_ORF3 in Beauveria bassiana (14). These trans-acting ERs are highly homologous (38-80% sequence identity; Fig.…”

The Reacquisition of Biotin Prototrophy in Saccharomyces cerevisiae Involved Horizontal Gene Transfer, Gene Duplication and Gene Clustering

“…The limited number of dispensable pathway clusters in S. cerevisiae is likely a reflection of the absence of secondary metabolism. Dispensable pathway clusters have been widely reported in other fungi including indolediterpene biosynthesis in Neotyphodium lolii (Young et al 2006) and Aspergillus flavus (Zhang et al 2004), the penicillin biosynthetic gene cluster in Penicillium chrysogenum (Smith et al1990;Abe et al 2002), P. nalgiovense (Cherry et al 1997). (Laich et al 1999), P. griseofulvum, and P. verrucosum (Laich et al 2002), the aflatoxin pathway in A. nidulans (Keller andAdams 1995) andA.…”

A PKS gene, pks-1, is involved in chaetoglobosin biosynthesis, pigmentation and sporulation in Chaetomium globosum

“…Molecular studies have also been performed to determine the biosynthetic principle of important bioactive polyketides, such as aflatoxin [17][18][19][20][21][22]. Regulatory networks governing secondary metabolism have been gradually uncovered in several fungal species, for example, the central roles of the G protein-cAMP-PKA pathway and the LaeA and VeA protein complex have been determined [19,[23][24][25].…”