Model of the complex formed between the H2 domain of the TATA box binding protein and the L(281-301) fragment of the human transcription factor TFIIA.
Additional interactions possibly involving the well-exposed H2 helical domain of hTBP and the acidic fragment L(281-301) of the non-conserved domain of hTFIIA have been proposed to account for the apparent discrepancies between the results of mutagenesis experiments on human proteins and the structure of the ternary complex TBP/TATA box/TFIIA established from yeast proteins by X-ray crystallography. To verify this hypothesis both peptides were synthesized and their structures studied by circular dichroism (CD), NMR and molecular modelling. These peptides exist preferentially under helical conformations in solution (30% TFE in H2O). An interaction between the two peptides was observed by fluorescence (Kapp 170 microM), CD and NMR techniques. Molecular modelling studies indicate that this complex could be stabilized by electrostatic interactions involving the glutamate Glu287 and aspartates (Asp290, Asp294, Asp297 and Asp298) of L(281-301)TFIIA and lysine residues (Lys133, Lys138 and Lys145) and arginine residues (Arg137, Arg140) of H2(TBP) in agreement with mutagenesis experiments. Similar studies could now be carried out with human proteins to demonstrate the biological relevance of this interaction.
Ramboarina
S
S
Département de Pharmacochimie Moléculaire et Structurale, INSERM U266 - CNRS URA D 1500, UFR des Sciences Pharmaceutiques et Biologiques, Paris, France.
Morellet
N
N
Petitjean
P
P
Roques
B P
BP
Fournié-Zaluski
M C
MC
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017433:Protein Structure, Secondary; D055672:Static Electricity; D016385:TATA Box; D035181:TATA-Box Binding Protein; D035561:Transcription Factor TFIIA; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics
D004268:DNA-Binding Proteins; D035181:TATA-Box Binding Protein; D035561:Transcription Factor TFIIA; D014157:Transcription Factors