title: Crystal structure of TBP-interacting protein (Tk-TIP26) and implications for its inhibition mechanism of the interaction between TBP and TATA-DNA.
abstract: TATA-binding protein (TBP)-interacting protein from the hyperthermophilic archaeon Thermococcus kodakaraensis strain KOD1 (Tk-TIP26) is a possible transcription regulatory protein in Thermococcales. Here, we report the crystal structure of Tk-TIP26 determined at 2.3 A resolution with multiple-wavelength anomalous dispersion (MAD) method. The overall structure of Tk-TIP26 consists of two domains. The N-terminal domain forms an alpha/beta structure, in which three alpha-helices enclose the central beta-sheet. The topology of this domain is similar to that of holliday junction resolvase Hjc from Pyrococcus furiosus. The C-terminal domain comprises three alpha-helices, six beta-strands, and two 3(10)-helices. In the dimer structure of Tk-TIP26, two molecules are related with the crystallographic twofold axis, and these molecules rigidly interact with each other via hydrogen bonds. The complex of Tk-TIP26/Tk-TBP is isolated and analyzed by SDS-PAGE and gel filtration column chromatography, resulting in a stoichiometric ratio of the interaction between Tk-TIP26 and Tk-TBP of 4:2, i.e., two dimer molecules of Tk-TIP26 formed a complex with one dimeric TBP. The electrostatic surfaces of Tk-TIP26 and TBP from Pyrocuccus woesei (PwTBP) allowed us to build a model of the Tk-TIP26/TBP complex, and to propose the inhibition mechanism where two dimer molecules of Tk-TIP26 bind to a dimeric TBP, preventing its binding to TATA-DNA.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Tomoki
authors.initials: T
authors.lastname: Matsuda
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Inoue
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Matsumura
authors.forename: Masaaki
authors.initials: M
authors.lastname: Morikawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kanaya
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kai
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000502:physiology; D018360:Crystallography, X-Ray; D019641:DNA, Archaeal / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019281:Dimerization; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016385:TATA Box; D035181:TATA-Box Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019712:Thermococcus / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000502:physiology
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D035181:TATA-Box Binding Protein; D014157:Transcription Factors