CCR4 is a glucose-regulated transcription factor whose leucine-rich repeat binds several proteins important for placing CCR4 in its proper promoter context.

Abstract

The yeast CCR4 protein is required for the expression of a number of genes involved in nonfermentative growth, including glucose-repressible ADH2, and is the only known suppressor of mutations in the SPT6 and SPT10 genes, two genes which are believed to be involved in chromatin maintenance. We show here that although CCR4 did not bind DNA under the conditions tested, it was able to activate transcription when fused to a heterologous DNA-binding domain. The transcriptional activation ability of CCR4, in contrast to that of many other activators, was glucose regulated. Two activation domains one of which was glucose responsive and encompassed a glutamine-proline-rich region similar to that found in other eukaryotic transcriptional factors were identified. The two transactivation regions, when separated from the leucine-rich repeat and the C terminus of CCR4, were unable to complement a defective ccr4 allele, suggesting that the leucine-rich repeat and the C terminus make contacts that link the activation regions to the proper gene context. Native immunoprecipitation of CCR4 revealed that CCR4 was complexed with at least four other proteins. The leucine-rich repeat of CCR4 was both necessary and sufficient for interaction with at least two of these factors. We propose that the leucine-rich repeat links CCR4 through its associated factors to its promoter context at ADH2 and other loci where it is required for proper transcriptional regulation.The general transcription factor CCR4 from Saccharomyces cerevisiae is required for the transcription of a number of genes involved in nonfermentative growth, including that of the ADH2 gene (encoding the glucose-repressible alcohol dehydrogenase II) (11). Strains containing a deletion of CCR4 also fail to grow at elevated temperatures on a nonfermentative medium, consistent with the global role played by CCR4 under these growth conditions (14). Cells lacking CCR4, however, display other phenotypes, suggesting that CCR4 is involved in processes in addition to that of controlling nonfermentative growth. ccr4 mutations display a cold sensitivity phenotype under glucose growth conditions, a phenotype observed for defects in transcription initiation complex factors such as TFIIB, RPB1, SRB2, and SRB4 (1,2,29,30,33,34,37,41). In addition, CCR4 is required for the elevated expression at the ADH2 locus and for the altered transcriptional initiation at the his4-9128 locus that results from defects in the SPT6 and SPT10 genes (14). The SPT6 and SPT10 genes encode factors that are responsible for maintaining proper transcriptional control over a wide range of genes, and SPT6 has been specifically implicated in the maintenance of chromatin structure (11,26,27,39,40). spt6 mutations, moreover, suppress defects in the global transactivators SNF2 and SNF5, which are known to be involved in maintaining proper nucleosome positioning (5,6,19,28,43 known suppressor of spt6, may be functioning to counteract the repressive effects that SPT6 has on chromatin structure. CCR4 is also required for ADR...

Characterization of Two Age-induced Intracisternal A-particle-related Transcripts in the Mouse Liver

“…40, and is therefore involved in auto-immune reactions in the aging mice. It could also encode a factor involved in transcriptional regulations: actually, the CCR4 protein is a transcription factor for the glucose-repressible genes in yeast (41), and recently Draper et al (42) identified a mouse protein that binds to the yeast CCR4 protein, resulting in a protein complex with evolutionarily conserved transcriptional functions. The presently identified ORF could be an exon of the mouse homologue (which still remains to be characterized) of the yeast CCR4 gene, and the IAP sequence be inserted within an intron of the corresponding gene.…”

Characterization of a Mammalian Gene Related to the Yeast CCR4 General Transcription Factor and Revealed by Transposon Insertion

“…2). The Xenopus, murine, and human proteins appear to lack the N-terminal region of yeast CCR4 (from amino acids 1 to 432), which contains a leucine-rich repeat region (amino acids 350 -467) and two activation domains (6). Yet, they display a significant similarity (close to 30%, including conservative amino acid changes) with the yeast CCR4 protein within their C-terminal domains, in a region corresponding to the second and third exons of the Xenopus, murine, and human genes.…”

“…13 and 15). In this respect, we had previously characterized three IAP transcripts of abnormal size (3,6, and 10 kb, named IAP-AR transcripts), which are induced exclusively in the liver of old mice (16). We have shown that the 10-kb IAP-AR transcript is initiated within the 5Ј-LTR of an * This work was supported by grants from the Association pour la Recherche sur le Cancer.…”

“…Although the mechanism of how yCCR4 functions remains undefined (yet the yCCR4 protein does not bind DNA by itself, Ref. 6), several lines of evidence suggest that the complex plays an important and conserved role in vertebrate gene regulation as well. Actually, there is increasing evidence for the existence of yCCR4-like proteins in higher eucaryotes.…”

“…It is part of a multi-subunit complex, several components of which have been characterized including DBF2, a cell cycle-regulated protein kinase (3), and proteins of the NOT family, involved in repression of transcription (4). yCCR4 displays a glutamine-rich N terminus, like many factors involved in transcriptional activation, and a leucine-rich repeat motif that is necessary for protein-protein interactions within the complex (5,6). Both motifs are required for transcriptional activation by yCCR4.…”