6uer | pdb_00006uer
Crystal form 2: Structure of TBP bound to C-C mismatch at pH 7
Structural highlights
FunctionTBP1_ARATH General transcription factor that functions at the core of the DNA-binding multiprotein factor TFIID. Binding of TFIID to the TATA box is the initial transcriptional step of the pre-initiation complex (PIC), playing a role in the activation of eukaryotic genes transcribed by RNA polymerase II. Publication Abstract from PubMedTranscription factors recognize specific genomic sequences to regulate complex gene-expression programs. Although it is well-established that transcription factors bind to specific DNA sequences using a combination of base readout and shape recognition, some fundamental aspects of protein-DNA binding remain poorly understood(1,2). Many DNA-binding proteins induce changes in the structure of the DNA outside the intrinsic B-DNA envelope. However, how the energetic cost that is associated with distorting the DNA contributes to recognition has proven difficult to study, because the distorted DNA exists in low abundance in the unbound ensemble(3-9). Here we use a high-throughput assay that we term SaMBA (saturation mismatch-binding assay) to investigate the role of DNA conformational penalties in transcription factor-DNA recognition. In SaMBA, mismatched base pairs are introduced to pre-induce structural distortions in the DNA that are much larger than those induced by changes in the Watson-Crick sequence. Notably, approximately 10% of mismatches increased transcription factor binding, and for each of the 22 transcription factors that were examined, at least one mismatch was found that increased the binding affinity. Mismatches also converted non-specific sites into high-affinity sites, and high-affinity sites into 'super sites' that exhibit stronger affinity than any known canonical binding site. Determination of high-resolution X-ray structures, combined with nuclear magnetic resonance measurements and structural analyses, showed that many of the DNA mismatches that increase binding induce distortions that are similar to those induced by protein binding-thus prepaying some of the energetic cost incurred from deforming the DNA. Our work indicates that conformational penalties are a major determinant of protein-DNA recognition, and reveals mechanisms by which mismatches can recruit transcription factors and thus modulate replication and repair activities in the cell(10,11). DNA mismatches reveal conformational penalties in protein-DNA recognition.,Afek A, Shi H, Rangadurai A, Sahay H, Senitzki A, Xhani S, Fang M, Salinas R, Mielko Z, Pufall MA, Poon GMK, Haran TE, Schumacher MA, Al-Hashimi HM, Gordan R Nature. 2020 Nov;587(7833):291-296. doi: 10.1038/s41586-020-2843-2. Epub 2020 Oct, 21. PMID:33087930[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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