Structural Similarity between Histone Chaperone Cia1p/Asf1p and DNA-Binding Protein NF-κB

Authors: Padmanabhan, Balasundaram; Kataoka, Kazuhiro; Umehara, Takashi; Yokoyama, Shigeyuki; Horikoshi, Masami

Source: The Journal of Biochemistry, Volume 138, Number 6, December 2005 , pp. 821-829(9)

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Abstract:

The structural relationships between histone-binding proteins and DNA-binding proteins are important, since nucleosome-interacting factors possess histone-binding and/or DNA-binding components. S. cerevisiae (Sc) Cia1p/Asf1p, a homologue of human CIA (CCG1-interacting factor A), is the most evolutionarily conserved histone chaperone, which facilitates nucleosome assembly by interacting with the nucleosome entry site of the core histones H3/H4. The crystal structure of the evolutionarily conserved domain (residues 1–169) of Cia1p (ScCia1p-ΔC2) was determined at 2.95 Å resolution. The refined model contains 166 residues in the asymmetric unit. The overall tertiary structure resembles a β-sandwich fold, and belongs to the “switched” immunoglobulin class of proteins. The crystal structure suggests that ScCia1p-ΔC2 is structurally related to the DNA-binding proteins, such as NF-κB and its family members. This is the first examination of the structural similarities between a histone chaperone and DNA-binding proteins. We discuss the possibilities that the strands β3 and β4, which possess highly electronegative surface potentials, are the important regions for the interaction with core histones, and that the histone chaperone ScCia1p/Asf1p and the DNA-binding protein NF-κB may have evolved from the same prototypal protein class.

Keywords: ASF1; chaperone; CIA; gene regulation; NFAT; NF-κB; nucleosome; p53; structure; transcription

Document Type: Research article

DOI: http://dx.doi.org/10.1093/jb/mvi182

Publication date: 2005-12-01