Genetics. Published Articles Ahead of Print: May 6, 2005, Copyright © 2005
doi:10.1534/genetics.105.041863


A more recent version of this article appeared on July 1, 2005.

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The inactivation of KlNOT4, a Kluyveromyces lactis gene encoding a component of the CCR4-NOT complex, reveals new regulatory functions

Cristina Mazzoni 1*, Agnese Serafini 1 and Claudio Falcone 1

1 University of Rome

* To whom correspondence should be addressed. E-mail: cristina.mazzoni{at}uniroma1.it.

Submitted on February 9, 2005
Revised on March 20, 2005
Accepted on 20 March 2005


Abstract

We have isolated the KlNOT4 gene of the yeast Kluyveromyces lactis encoding a component of the evolutionary conserved CCR4-NOT complex. We show that inactivation of the gene leads to pleiotropic defects that were differently suppressed by the NOT4 gene of S. cerevisiae, indicating that these genes have overlapping, but not identical functions. K. lactis strains lacking Not4p were defective in fermentation and showed reduced transcription of glucose transporter and glycolytic genes, which are phenotypes that are not found in the corresponding mutant of S. cerevisiae. We also show that Not4 proteins control the respiratory pathway in both yeasts, although with some differences. They activate transcription of KlACS2 and KlCYC1, but repress KlICL1, ScACS1, ScICL1 and ScCYC1. Altogether, our results indicate Not4p is a pivotal factor involved in the regulation of carbon metabolism in yeast.

Key Words: CCR4-NOT, Kluyveromyces lactis, carbon metabolism, cell wall, transcriptional regulation