The Zn 2 2 (II) Cys binuclear cluster of TamA is required for activation of gdhA expression in Aspergillus nidulans.

Ref ID: 18339

Author:

Downes, Damien J. , Brendan
1,2
L. Taig , Sara Lewis , Richard B. Todd , Meryl A. Davis

Author address:

Department of Genetics, University of Melbourne, Vic, Australia. Department of Plant
Pathology, Kansas State University, KS, USA

Full conference title:

Asperfest 8

Abstract:

NADP-dependent glutamate dehydrogenase (NADP-GDH) encoded by gdhA is required for the assimilation of alternate nitrogen sources through
ammonium in Aspergillus nidulans. Previousstudies have shown that gdhA expression is regulated by three transcription factors: the major transcription
activator of nitrogen metabolic genes, AreA, the regulator of leucine biosynthesis, LeuB, and TamA a co-activator of AreA that also interacts with LeuB.
At the gdhA promoter TamA isthe major contributor to gene expression, unlike at most nitrogen assimilation promoters, where TamA plays a minor role
in gene activation. We show that mutation of the DNA binding domain in any of AreA, LeuB or TamA reduces activity at the gdhA promoter. Significantly
2 2
this suggests a role for the Zn(II) Cys binuclear cluster of TamA, which is dispensable for function at other promoters. Using fragments of the gdhA
promoter fused to the lacZ reporter gene we identified two core regulatory regions in the promoter. One regulatory region contains a potential site of action
for TamA close to putative binding sites for both AreA and LeuB. At the second regulatory site LeuB acts independently as a modulated activator/repressor
to mediate glutamate feedback regulation.

Abstract Number: 17)

Conference Year: 2011

Link to conference website: NULL

New link: NULL

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