Interaction of PC4 with melted DNA inhibits transcription.
PC4 is a nuclear DNA-binding protein that stimulates activator-dependent class II gene transcription in vitro. Recent biochemical and X-ray analyses have revealed a unique structure within the C-terminal domain of PC4 that binds tightly to unpaired double-stranded (ds)DNA. The cellular function of this evolutionarily conserved dimeric DNA-binding fold is unknown. Here we demonstrate that PC4 represses transcription through this motif. Interaction with melted promoters is not required for activator-dependent transcription in vitro. The inhibitory activity is attenuated on bona fide promoters by (i) transcription factor TFIIH and (ii) phosphorylation of PC4. PC4 remains a potent inhibitor of transcription in regions containing unpaired ds DNA, in single-stranded DNA that can fold into two antiparallel strands, and on DNA ends. Our observations are consistent with a novel inhibitory function of PC4.
Laboratorium voor Fysiologische Chemie, Utrecht University, Stratenum Universiteitsweg 100, Bijvoet Center for Biomolecular Research, Utrecht, The Netherlands.
S
S
Werten
G
G
Stelzer
A
A
Goppelt
F M
FM
Langen
P
P
Gros
H T
HT
Timmers
P C
PC
Van der Vliet
M
M
Meisterernst
D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009692:Nucleic Acid Heteroduplexes / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011487:Protein Conformation; D012319:RNA Polymerase II; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009692:Nucleic Acid Heteroduplexes; D019384:Nucleic Acid Synthesis Inhibitors; D010750:Phosphoproteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D012319:RNA Polymerase II