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Characterization of the mupirocin biosynthesis gene cluster from Pseudomonas fluorescens NCIMB 10586
A Kassem El-Sayed1, Joanne Hothersall, Sian M Cooper
1School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
Abstract:
The polyketide antibiotic mupirocin (pseudomonic acid) produced by Pseudomonas fluorescens NCIMB 10586 competitively inhibits bacterial isoleucyl-tRNA synthase and is useful in controlling Staphylococcus aureus, particularly methicillin-resistant Staphylococcus aureus. The 74 kb mupirocin biosynthesis cluster has been sequenced, and putative enzymatic functions of many of the open reading frames (ORFs) have been identified. The mupirocin cluster is a combination of six larger ORFs (mmpA-F), containing several domains resembling the multifunctional proteins of polyketide synthase and fatty acid synthase type I systems, and individual genes (mupA-X and macpA-E), some of which show similarity to type II systems (mupB, mupD, mupG, and mupS). Gene knockout experiments demonstrated the importance of regions in mupirocin production, and complementation of the disrupted gene confirmed that the phenotypes were not due to polar effects. A model for mupirocin biosynthesis is presented based on the sequence and biochemical evidence.
Insights
Mupirocin, an antibiotic from Pseudomonas fluorescens, inhibits bacterial isoleucyl-tRNA synthase. Its 74 kb biosynthesis gene cluster was sequenced, revealing key genes for producing this important Staphylococcus aureus treatment.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Mupirocin (pseudomonic acid) is a polyketide antibiotic effective against Staphylococcus aureus, including MRSA.
- It functions by competitively inhibiting bacterial isoleucyl-tRNA synthase.
Purpose of the Study:
- To elucidate the genetic basis of mupirocin biosynthesis.
- To identify the enzymatic functions within the mupirocin gene cluster.
Main Methods:
- Sequencing of the 74 kb mupirocin biosynthesis gene cluster.
- Identification of open reading frames (ORFs) and their putative enzymatic functions.
- Gene knockout and complementation experiments to validate gene functions.
Main Results:
- The mupirocin cluster comprises six large ORFs (mmpA-F) and individual genes (mupA-X, macpA-E).
- ORF domains resemble polyketide synthase and fatty acid synthase type I systems, with some genes showing type II system similarity.
- Gene knockout studies confirmed the essentiality of specific regions for mupirocin production.
Conclusions:
- A detailed model for mupirocin biosynthesis has been proposed based on sequence and biochemical data.
- Understanding the biosynthesis pathway provides insights into antibiotic production and potential engineering strategies.