| Structural highlights
Function
[PAF1_HUMAN] Component of the PAF1 complex (PAF1C) which has multiple functions during transcription by RNA polymerase II and is implicated in regulation of development and maintenance of embryonic stem cell pluripotency. PAF1C associates with RNA polymerase II through interaction with POLR2A CTD non-phosphorylated and 'Ser-2'- and 'Ser-5'-phosphorylated forms and is involved in transcriptional elongation, acting both indepentently and synergistically with TCEA1 and in cooperation with the DSIF complex and HTATSF1. PAF1C is required for transcription of Hox and Wnt target genes. PAF1C is involved in hematopoiesis and stimulates transcriptional activity of KMT2A/MLL1; it promotes leukemogenesis through association with KMT2A/MLL1-rearranged oncoproteins, such as KMT2A/MLL1-MLLT3/AF9 and KMT2A/MLL1-MLLT1/ENL. PAF1C is involved in histone modifications such as ubiquitination of histone H2B and methylation on histone H3 'Lys-4' (H3K4me3). PAF1C recruits the RNF20/40 E3 ubiquitin-protein ligase complex and the E2 enzyme UBE2A or UBE2B to chromatin which mediate monoubiquitination of 'Lys-120' of histone H2B (H2BK120ub1); UB2A/B-mediated H2B ubiquitination is proposed to be coupled to transcription. PAF1C is involved in mRNA 3' end formation probably through association with cleavage and poly(A) factors. In case of infection by influenza A strain H3N2, PAF1C associates with viral NS1 protein, thereby regulating gene transcription. Connects PAF1C with the RNF20/40 E3 ubiquitin-protein ligase complex. Involved in polyadenylation of mRNA precursors. Has oncogenic activity in vivo and in vitro.[1] [2] [3] [4] [5] [6] [7]
Publication Abstract from PubMed
The highly conserved Paf1 complex (PAF1C) plays critical roles in RNA polymerase II transcription elongation and in the regulation of histone modifications. It has also been implicated in other diverse cellular activities, including posttranscriptional events, embryonic development and cell survival and maintenance of embryonic stem cell identity. Here, we report the structure of the human Paf1/Leo1 subcomplex within PAF1C. The overall structure reveals that the Paf1 and Leo1 subunits form a tightly associated heterodimer through antiparallel beta-sheet interactions. Detailed biochemical experiments indicate that Leo1 binds to PAF1C through Paf1 and that the Ctr9 subunit is the key scaffold protein in assembling PAF1C. Furthermore, we show that the Paf1/Leo1 heterodimer is necessary for its binding to histone H3, the histone octamer, and nucleosome in vitro. Our results shed light on the PAF1C assembly process and substrate recognition during various PAF1C-coordinated histone modifications.
Structural insights into Paf1 complex assembly and histone binding.,Chu X, Qin X, Xu H, Li L, Wang Z, Li F, Xie X, Zhou H, Shen Y, Long J Nucleic Acids Res. 2013 Sep 14. PMID:24038468[8]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Kim J, Guermah M, McGinty RK, Lee JS, Tang Z, Milne TA, Shilatifard A, Muir TW, Roeder RG. RAD6-Mediated transcription-coupled H2B ubiquitylation directly stimulates H3K4 methylation in human cells. Cell. 2009 May 1;137(3):459-71. doi: 10.1016/j.cell.2009.02.027. PMID:19410543 doi:10.1016/j.cell.2009.02.027
- ↑ Chen Y, Yamaguchi Y, Tsugeno Y, Yamamoto J, Yamada T, Nakamura M, Hisatake K, Handa H. DSIF, the Paf1 complex, and Tat-SF1 have nonredundant, cooperative roles in RNA polymerase II elongation. Genes Dev. 2009 Dec 1;23(23):2765-77. doi: 10.1101/gad.1834709. PMID:19952111 doi:10.1101/gad.1834709
- ↑ Muntean AG, Tan J, Sitwala K, Huang Y, Bronstein J, Connelly JA, Basrur V, Elenitoba-Johnson KS, Hess JL. The PAF complex synergizes with MLL fusion proteins at HOX loci to promote leukemogenesis. Cancer Cell. 2010 Jun 15;17(6):609-21. doi: 10.1016/j.ccr.2010.04.012. PMID:20541477 doi:10.1016/j.ccr.2010.04.012
- ↑ Kim J, Guermah M, Roeder RG. The human PAF1 complex acts in chromatin transcription elongation both independently and cooperatively with SII/TFIIS. Cell. 2010 Feb 19;140(4):491-503. doi: 10.1016/j.cell.2009.12.050. PMID:20178742 doi:10.1016/j.cell.2009.12.050
- ↑ Nagaike T, Logan C, Hotta I, Rozenblatt-Rosen O, Meyerson M, Manley JL. Transcriptional activators enhance polyadenylation of mRNA precursors. Mol Cell. 2011 Feb 18;41(4):409-18. doi: 10.1016/j.molcel.2011.01.022. PMID:21329879 doi:10.1016/j.molcel.2011.01.022
- ↑ Marazzi I, Ho JS, Kim J, Manicassamy B, Dewell S, Albrecht RA, Seibert CW, Schaefer U, Jeffrey KL, Prinjha RK, Lee K, Garcia-Sastre A, Roeder RG, Tarakhovsky A. Suppression of the antiviral response by an influenza histone mimic. Nature. 2012 Mar 14;483(7390):428-33. doi: 10.1038/nature10892. PMID:22419161 doi:10.1038/nature10892
- ↑ Chu X, Qin X, Xu H, Li L, Wang Z, Li F, Xie X, Zhou H, Shen Y, Long J. Structural insights into Paf1 complex assembly and histone binding. Nucleic Acids Res. 2013 Sep 14. PMID:24038468 doi:10.1093/nar/gkt819
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