Document Detail

Genetic analysis of biosurfactant production in Ustilago maydis.
MedLine Citation:
PMID:  15932999     Owner:  NLM     Status:  MEDLINE    
The dimorphic basidiomycete Ustilago maydis produces large amounts of surface-active compounds under conditions of nitrogen starvation. These biosurfactants consist of derivatives of two classes of amphipathic glycolipids. Ustilagic acids are cellobiose lipids in which the disaccharide is O-glycosidically linked to 15,16-dihydroxyhexadecanoic acid. Ustilipids are mannosylerythritol lipids derived from acylated beta-d-mannopyranosyl-d-erythritol. Whereas the chemical structure of these biosurfactants has been determined, the genetic basis for their biosynthesis and regulation is largely unknown. Here we report the first identification of two genes, emt1 and cyp1, that are essential for the production of fungal extracellular glycolipids. emt1 is required for mannosylerythritol lipid production and codes for a protein with similarity to prokaryotic glycosyltransferases involved in the biosynthesis of macrolide antibiotics. We suggest that Emt1 catalyzes the synthesis of mannosyl-d-erythritol by transfer of GDP-mannose. Deletion of the gene cyp1 resulted in complete loss of ustilagic acid production. Cyp1 encodes a cytochrome P450 monooxygenase which is highly related to a family of plant fatty acid hydroxylases. Therefore we assume that Cyp1 is directly involved in the biosynthesis of the unusual 15,16-dihydroxyhexadecanoic acid. We could show that mannosylerythritol lipid production is responsible for hemolytic activity on blood agar, whereas ustilagic acid secretion is required for long-range pheromone recognition. The mutants described here allow for the first time a genetic analysis of glycolipid production in fungi.
Sandra Hewald; Katharina Josephs; Michael Bölker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  71     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-06-03     Completed Date:  2005-08-11     Revised Date:  2010-09-21    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3033-40     Citation Subset:  IM    
Philipps-Universität Marburg, Fachbereich Biologie, 35032 Marburg, Germany.
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MeSH Terms
Amino Acid Sequence
Cytochrome P-450 Enzyme System / genetics,  metabolism
Fungal Proteins / genetics*,  metabolism
Gene Expression Regulation, Fungal*
Glycolipids / biosynthesis*
Glycosyltransferases / chemistry,  genetics,  metabolism
Mixed Function Oxygenases / genetics,  metabolism
Molecular Sequence Data
Sequence Alignment
Surface-Active Agents / metabolism*
Ustilago / genetics*,  metabolism
Reg. No./Substance:
0/Fungal Proteins; 0/Glycolipids; 0/Surface-Active Agents; 0/mannosylerythritol lipid; 9035-51-2/Cytochrome P-450 Enzyme System; EC 1.-/Mixed Function Oxygenases; EC 2.4.-/Glycosyltransferases

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