Paf1p, an RNA polymerase II-associated factor in Saccharomyces cerevisiae, may have both positive and negative roles in transcription.
Regulated transcription initiation requires, in addition to RNA polymerase II and the general transcription factors, accessory factors termed mediators or adapters. We have used affinity chromatography to identify a collection of factors that associate with Saccharomyces cerevisiae RNA polymerase II (P. A. Wade, W. Werel, R. C. Fentzke, N. E. Thompson, J. F. Leykam, R. R. Burgess, J. A. Jaehning, and Z. F. Burton, submitted for publication). Here we report identification and characterization of a gene encoding one of these factors, PAF1 (for RNA polymerase-associated factor 1). PAF1 encodes a novel, highly charged protein of 445 amino acids. Disruption of PAF1 in S. cerevisiae leads to pleiotropic phenotypic traits, including slow growth, temperature sensitivity, and abnormal cell morphology. Consistent with a possible role in transcription, Paf1p is localized to the nucleus. By comparing the abundances of many yeast transcripts in isogenic wild-type and paf1 mutant strains, we have identified genes whose expression is affected by PAF1. In particular, disruption of PAF1 decreases the induction of the galactose-regulated genes three- to fivefold. In contrast, the transcript level of MAK16, an essential gene involved in cell cycle regulation, is greatly increased in the paf1 mutant strain. Paf1p may therefore be required for both positive and negative regulation of subsets of yeast genes. Like Paf1p, the GAL11 gene product is found associated with RNA polymerase II and is required for regulated expression of many yeast genes including those controlled by galactose. We have found that a gal11 paf1 double mutant has a much more severe growth defect than either of the single mutants, indicating that these two proteins may function in parallel pathways to communicate signals from regulatory factors to RNA polymerase II.
Shi
X
X
Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, Denver 80262, USA.
Finkelstein
A
A
Wolf
A J
AJ
Wade
P A
PA
Burton
Z F
ZF
Jaehning
J A
JA
D000595:Amino Acid Sequence; D001483:Base Sequence; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000737:chemistry; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005690:Galactose / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005804:Genes, Lethal; D056892:Mediator Complex; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D012319:RNA Polymerase II / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D005656:Fungal Proteins; C058337:GAL11 protein, S cerevisiae; C097699:MAK16 protein, S cerevisiae; D056892:Mediator Complex; D009687:Nuclear Proteins; C097698:PAF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D012319:RNA Polymerase II; D005690:Galactose