title: Structure of the Trichomonas vaginalis Myb3 DNA-binding domain bound to a promoter sequence reveals a unique C-terminal β-hairpin conformation.
abstract: Trichomonas vaginalis Myb3 transcription factor (tvMyb3) recognizes the MRE-1 promoter sequence and regulates ap65-1 gene, which encodes a hydrogenosomal malic enzyme that may play a role in the cytoadherence of the parasite. Here, we identified tvMyb3(53-180) as the essential fragment for DNA recognition and report the crystal structure of tvMyb3(53-180) bound to MRE-1 DNA. The N-terminal fragment adopts the classical conformation of an Myb DNA-binding domain, with the third helices of R2 and R3 motifs intercalating in the major groove of DNA. The C-terminal extension forms a β-hairpin followed by a flexible tail, which is stabilized by several interactions with the R3 motif and is not observed in other Myb proteins. Interestingly, this unique C-terminal fragment does not stably connect with DNA in the complex structure but is involved in DNA binding, as demonstrated by NMR chemical shift perturbation, (1)H-(15)N heteronuclear-nuclear Overhauser effect and intermolecular paramagnetic relaxation enhancement. Site-directed mutagenesis also revealed that this C-terminal fragment is crucial for DNA binding, especially the residue Arg(153) and the fragment K(170)KRK(173). We provide a structural basis for MRE-1 DNA recognition and suggest a possible post-translational regulation of tvMyb3 protein.
authors: Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC.
authors: Shu-Yi
authors: SY
authors: Wei
authors: Yuan-Chao
authors: YC
authors: Lou
authors: Jia-Yin
authors: JY
authors: Tsai
authors: Meng-Ru
authors: MR
authors: Ho
authors: Chun-Chi
authors: CC
authors: Chou
authors: M
authors: M
authors: Rajasekaran
authors: Hong-Ming
authors: HM
authors: Hsu
authors: Jung-Hsiang
authors: JH
authors: Tai
authors: Chwan-Deng
authors: CD
authors: Hsiao
authors: Chinpan
authors: C
authors: Chen
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D016054:DNA, Protozoan / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics; D014246:Trichomonas vaginalis
chemical_list: D016054:DNA, Protozoan; D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D014157:Transcription Factors