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Lookup NU author(s): Dr Carys Watts,
Dr Heather Lamb,
Professor Alastair Hawkins
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The QutR protein is a multidomain repressor protein that interacts with the QutA activator protein. Both proteins are active in the signal transduction pathway that regulates transcription of the quinic acid utilization (qut) gene cluster of the microbial eukaryote Aspergillus nidulans. In the presence of quinate, production of mRNA from the eight genes of the qut pathway is stimulated by the QutA activator protein. The QutR protein plays a key role in signal recognition and transduction, and a deletion analysis has shown that the N-terminal 88 amino acids are sufficient to inactivate QutA function in vivo. Using surface plasmon resonance we show here that the N-terminal 88 amino acids of QutR are able to bind in vitro to a region of QutA that genetic analysis has previously implicated in transcription activation. We further show that increasing the concentration of a full-length (missense) mutant QutR protein in the original mutant strain can restore its repressing function. This is interpreted to mean that the qutR mutation in this strain increases the equilibrium dissociation constant for the interaction between QutA and QutR. We propose a model in which the QutA and QutR proteins are in dynamic equilibrium between bound (transcriptionally inactive) and unbound (transcriptionally active) states. © 2002 Wiley-Liss, Inc.
Author(s): Hawkins AR; Watts C; Lamb HK; Si-Hoe SM; Levett LJ; Coggins JR
Publication type: Article
Publication status: Published
Journal: Proteins: Structure, Function and Genetics
ISSN (print): 0887-3585
Publisher: John Wiley & Sons, Inc.
PubMed id: 12112685
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