title: The crystal structure of CCG1/TAF(II)250-interacting factor B (CIB).
abstract: The general transcription initiation factor TFIID and its interactors play critical roles in regulating the transcription from both naked and chromatin DNA. We have isolated a novel TFIID interactor that we denoted as CCG1/TAF(II)250-interacting factor B (CIB). We show here that CIB activates transcription. To further understand the function of this protein, we determined its crystal structure at 2.2-Angstroms resolution. The tertiary structure of CIB reveals an alpha/beta-hydrolase fold that resembles structures in the prokaryotic alpha/beta-hydrolase family proteins. It is not similar in structure or primary sequence to any eukaryotic transcription or chromatin factors that have been reported to date. CIB possesses a conserved catalytic triad that is found in other alpha/beta-hydrolases, and our in vitro studies confirmed that it bears hydrolase activity. However, CIB differs from other alpha/beta-hydrolases in that it lacks a binding site excursion, which facilitates the substrate selectivity of the other alpha/beta-hydrolases. Further functional characterization of CIB based on its tertiary structure and through biochemical studies may provide novel insights into the mechanisms that regulate eukaryotic transcription.
authors.affiliation: Horikoshi Gene Selector Project, Exploratory Research for Advanced Technology, Japan Science and Technology Corporation, 5-9-6 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
authors.forename: Balasundaram
authors.initials: B
authors.lastname: Padmanabhan
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuzuhara
authors.forename: Naruhiko
authors.initials: N
authors.lastname: Adachi
authors.forename: Masami
authors.initials: M
authors.lastname: Horikoshi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D051548:Histone Acetyltransferases; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D035381:TATA-Binding Protein Associated Factors / Q000737:chemistry* / Q000378:metabolism; D035362:Transcription Factor TFIID / Q000737:chemistry* / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D051548:Histone Acetyltransferases; C069001:TATA-binding protein associated factor 250 kDa