The Paf1 complex is essential for histone monoubiquitination by the Rad6-Bre1 complex, which signals for histone methylation by COMPASS and Dot1p.
Monoubiquitination of histone H2B, catalyzed by Rad6-Bre1, is required for methylation of histone H3 on lysines 4 and 79, catalyzed by the Set1-containing complex COMPASS and Dot1p, respectively. The Paf1 protein complex, which associates with RNA polymerase II, is known to be required for these histone H3 methylation events. During the early elongation stage of transcription, the Paf1 complex is required for association of COMPASS with RNA polymerase II, but the role the Paf1 complex plays at the promoter has not been clear. We present evidence that the Paf1 complex is required for monoubiquitination of histone H2B at promoters. Strains deleted for several components of the Paf1 complex are defective in monoubiquitination of histone H2B, which results in the loss of methylation of lysines 4 and 79 of histone H3. We also show that Paf1 complex is required for the interaction of Rad6 and COMPASS with RNA polymerase II. Finally, we show that the Paf1 complex is required for Rad6-Bre1 catalytic activity but not for the recruitment of Rad6-Bre1 to promoters. Thus, in addition to its role during the elongation phase of transcription, the Paf1 complex appears to activate the function but not the placement of the Rad6-Bre1 ubiquitin-protein ligase at the promoters of active genes.
Wood
Adam
A
Department of Biochemistry, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA.
Schneider
Jessica
J
Dover
Jim
J
Johnston
Mark
M
Shilatifard
Ali
A
D004257:DNA Polymerase II / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000378:metabolism*; D008025:Ligases / Q000378:metabolism*; D008239:Lysine; D008745:Methylation; D009687:Nuclear Proteins / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes
C472168:Bre1 protein, S cerevisiae; D006657:Histones; D009687:Nuclear Proteins; C097698:PAF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; C416235:Dot1 protein, S cerevisiae; D011495:Histone-Lysine N-Methyltransferase; C471606:RAD6 protein, S cerevisiae; D044763:Ubiquitin-Conjugating Enzymes; D012319:RNA Polymerase II; D004257:DNA Polymerase II; D008025:Ligases; D008239:Lysine