7ohc

From Proteopedia

Cryo-EM structure of nucleosome core particle composed of the Widom 601 DNA sequence

Structural highlights

7ohc is a 10 chain structure with sequence from Xenopus laevis and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 2.5Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

H32_XENLA Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.

Publication Abstract from PubMed

The TATA box-binding protein (TBP) is highly conserved throughout eukaryotes and plays a central role in the assembly of the transcription preinitiation complex (PIC) at gene promoters. TBP binds and bends DNA, and directs adjacent binding of the transcription factors TFIIA and TFIIB for PIC assembly. Here, we show that yeast TBP can bind to a nucleosome containing the Widom-601 sequence and that TBP-nucleosome binding is stabilized by TFIIA. We determine three cryo-electron microscopy (cryo-EM) structures of TBP-nucleosome complexes, two of them containing also TFIIA. TBP can bind to superhelical location (SHL) -6, which contains a TATA-like sequence, but also to SHL +2, which is GC-rich. Whereas binding to SHL -6 can occur in the absence of TFIIA, binding to SHL +2 is only observed in the presence of TFIIA and goes along with detachment of upstream terminal DNA from the histone octamer. TBP-nucleosome complexes are sterically incompatible with PIC assembly, explaining why a promoter nucleosome generally impairs transcription and must be moved before initiation can occur.

Structures and implications of TBP-nucleosome complexes.,Wang H, Xiong L, Cramer P Proc Natl Acad Sci U S A. 2021 Jul 27;118(30):e2108859118. doi: , 10.1073/pnas.2108859118. PMID:34301908^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Wang H, Xiong L, Cramer P. Structures and implications of TBP-nucleosome complexes. Proc Natl Acad Sci U S A. 2021 Jul 27;118(30):e2108859118. PMID:34301908 doi:10.1073/pnas.2108859118