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The distal GATA sequences of the sid1 promoter of Ustilago maydis mediate iron repression of siderophore production and interact directly with Urbs1, a GATA family transcription factor
Author(s) -
An Zhiqiang,
Mei Baigen,
Yuan Walter M.,
Leong Sally A.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.7.1742
Subject(s) - biology , ustilago , gata transcription factor , transcription factor , psychological repression , genetics , transcription (linguistics) , siderophore , promoter , microbiology and biotechnology , gene , gene expression , linguistics , philosophy
The sid1 and urbs1 genes encode L‐ornithine N 5 ‐oxygenase and a GATA family transcription regulator, respectively, for siderophore biosynthesis in Ustilago maydis . The basic promoter and iron‐regulatory sequences of the U.maydis sid1 gene were defined by fusing restriction and Bal 31 nuclease‐generated deletion fragments of the promoter region with the Escherichia coli β‐glucuronidase (GUS) reporter gene. Sequences required for basal expression of sid1 mapped within 1043 bp upstream of the translation start site and include the first untranslated exon and first intron. Sequences needed for iron‐regulated expression of sid1 were localized to a 306 bp region mapping 2.3 and 2.6 kb upstream of the ATG. The 306 bp region contains two G/TGATAA sequences, consensus DNA binding sites of GATA family transcription factors. Deletion or site‐directed mutation of either or both GATA sequences resulted in deregulated expression of sid1 . In vitro DNA binding studies showed that Urbs1 binds to the 3′‐GATA site in the 306 bp iron‐responsive region. However, deletion of 1.1 kb between the distal GATA sites and the basal promoter region led to deregulated expression of GUS, indicating that these GATA sequences are by themselves insufficient to regulate sid1 . In vitro DNA binding and in vivo reporter gene analysis revealed that siderophores are not co‐repressors of Urbs1.