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Published on: January 13, 2017
[Identification of a pigment-polyketide synthase gene deleted mutant of Monascus ruber M7]
Objective:
To reveal the function of a polyketide synthase gene (pksPT), probably responsible for the synthesis of Monascus pigments in Monascus ruber M7.
Methods:
The pksPT was analyzed using bioinformatics method; it was disrupted using Agrobacterium tumefaciens mediated transformation method, generating the pksPT-deleted mutant (ΔpksPT). Colonial morphology, conidial germination, pigment and citrinin production, and growth rate of ΔpksPT were analyzed.
Results:
The pksPT with the length of 8687 bp encoded a putative protein of 2690 amino acids, which is a non-reduced type III polyketide synthase and has some active domains with the arrangement of KS (β-ketosynthase)-AT (Acyltransferase)-ACP (Acyl carrier protein)-ACP-ME (Methyltransferase). The analysis of ΔpksPT displayed that it could generate cleistothecum and conidum normally and was unable to produce any kinds of Monascus pigments; compared to M7, the growth rate of ΔpksPT was increased obviously and the yield of citrinin in ΔpksPT was increased about 2. 8 times.
Conclusion:
pksPT is of extremely importance to the biosynthetic pathways of Monascus pigments in M7 and the synthesis of Monascus pigments gives a significant effect on the produce of citrinin as well as the growth of M7.
Insights
The polyketide synthase gene (pksPT) is crucial for Monascus pigment production in Monascus ruber M7. Deleting this gene boosted citrinin yield and fungal growth, indicating pigment synthesis impacts these factors.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Monascus pigments are valuable natural colorants.
- The genetic basis for Monascus pigment biosynthesis is not fully understood.
- Polyketide synthases (PKS) are key enzymes in secondary metabolite production.
Purpose of the Study:
- To elucidate the function of the polyketide synthase gene (pksPT) in Monascus ruber M7.
- To determine the role of pksPT in Monascus pigment synthesis.
- To investigate the impact of pksPT deletion on other metabolites and fungal growth.
Main Methods:
- Bioinformatic analysis of the pksPT gene.
- Gene disruption using Agrobacterium tumefaciens mediated transformation to create a pksPT-deleted mutant (ΔpksPT).
- Analysis of colonial morphology, conidial germination, pigment and citrinin production, and growth rate.
Main Results:
- The pksPT gene encodes a non-reduced type III polyketide synthase with conserved active domains.
- The ΔpksPT mutant failed to produce Monascus pigments.
- The ΔpksPT mutant exhibited enhanced growth rate and approximately 2.8-fold increased citrinin yield compared to the wild type M7.
Conclusions:
- The pksPT gene is essential for Monascus pigment biosynthesis in M7.
- Monascus pigment synthesis significantly influences citrinin production and fungal growth.
- This study provides insights into the metabolic regulation of secondary metabolites in Monascus species.
