Promoter study was performed to understand the transcriptional control of Delta(9)-desaturase gene of Mucor rouxii. Several putative cis-elemients involved in lipid metabolism were mapped by computational analysis. 5' deletion analysis shows the presence of elements with repressing activity, especially in 122 bp located upstream of the transcription start site. Truncation of these repressor domains showed that the promoter of M. rouxii is functional in Saccharomyces cerevisiae without additional components and is insensitive to nutritional depletion. The promoter also drove effectively the expression of a M. rouxii Delta(12) -desaturase gene, and the linoleic acid content increased with the age of the yeast culture in parallel with the promoter activity. This approach provides a genetic tool for programming heterologous protein production in the yeast. (c) 2005 Elsevier Inc. All rights reserved.