A role for TBP dimerization in preventing unregulated gene expression.
The recruitment of the TATA box-binding protein (TBP) to promoters in vivo is often rate limiting in gene expression. We present evidence that TBP negatively autoregulates its accessibility to promoter DNA in yeast through dimerization. The crystal structure of TBP dimers was used to design point mutations in the dimer interface. These mutants are impaired for dimerization in vitro, and in vivo they generate large increases in activator-independent gene expression. Overexpression of wild-type TBP suppresses these mutants, possibly by heterodimerizing with them. In addition to loss of autorepression, dimerization-defective TBPs are rapidly degraded in vivo. Direct detection of TBP dimers in vivo was achieved through chemical cross-linking. Taken together, the data suggest that TBP dimerization prevents unregulated gene expression and its own degradation.
Jackson-Fisher
A J
AJ
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802, USA.
Chitikila
C
C
Mitra
M
M
Pugh
B F
BF
D019943:Amino Acid Substitution; D001667:Binding, Competitive; D003432:Cross-Linking Reagents; D003460:Crystallization; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D020043:Genes, Essential / Q000235:genetics; D006207:Half-Life; D008957:Models, Genetic; D008958:Models, Molecular; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016385:TATA Box / Q000235:genetics / Q000502:physiology; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019473:Transcription Factors, TFII / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation
D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C106785:TAF1 protein, S cerevisiae; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D004247:DNA