Author
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YUAN, WALTER - UNIVERSITY OF WISCONSIN |
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Leong, Sally |
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Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 2/1/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Two genes required for ferrichrome siderophore biosynthesis in Ustilago maydis, have been cloned and characterized. sid1 encodes ornithine-Nx10**5-oxygenase, while sid2 encodes a ferrichrome peptide synthetase. The two sid genes are divergently transcribed from a 4.5 kb intergenic region. Urbs1, a GATA-family transcription factor, regulates sid gene expression under different iron conditions. Multiple GATA motifs have been identified in the intergenic region by DNA sequence analysis. Using site-directed mutagenesis and gel mobility shift analysis, one pair of GATA sequences in the near center of the intergenic region was shown to be crucial for iron-mediated regulation of sid1 expression. It is hypothesized that sid1 and sid2 expression may be divergently governed by the same promoter region. A twin-reporter system will be exploited to test this hypothesis. LacZ and GUS reporter genes will be translationally fused in opposite orientations with the intergenic region in a self-replicating vector and site-directed mutagenesis will be performed to identify important cis elements. To eliminate copy number effects, the key dual reporter constructs will be further tested at single copy in U. maydis by gene replacement. The extent of the sid gene cluster and its coregulation will be assessed by Northern hybridization analysis of RNA extracted from cells grown in low and high iron media. |
