Sub1 and RPA associate with RNA polymerase II at different stages of transcription

Timothy W. Sikorski, Scott B. Ficarro, John Holik, Tae Soo Kim, Oliver J. Rando, Jarrod A. Marto, Stephen Buratowski

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


Single-stranded DNA-binding proteins play many roles in nucleic acid metabolism, but their importance during transcription remains unclear. Quantitative proteomic analysis of RNA polymerase II (RNApII) preinitiation complexes (PICs) identified Sub1 and the replication protein A complex (RPA), both of which bind single-stranded DNA (ssDNA). Sub1, homolog of mammalian coactivator PC4, exhibits strong genetic interactions with factors necessary for promoter melting. Sub1 localizes near the transcription bubble in vitro and binds to promoters in vivo dependent upon PIC assembly. In contrast, RPA localizes to transcribed regions of active genes, strongly correlated with transcribing RNApII but independently of replication. RFA1 interacts genetically with transcription elongation factor genes. Interestingly, RPA levels increase at active promoters in cells carrying a Sub1 deletion or ssDNA-binding mutant, suggesting competition for a common binding site. We propose that Sub1 and RPA interact with the nontemplate strand of RNApII complexes during initiation and elongation, respectively.

Original languageEnglish
Pages (from-to)397-409
Number of pages13
JournalMolecular Cell
Issue number3
StatePublished - 4 Nov 2011


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