title: Solution structure and backbone dynamics of the DNA-binding domain of FOXP1: insight into its domain swapping and DNA binding.
abstract: FOXP1 belongs to the P-subfamily of forkhead transcription factors and contains a conserved forkhead DNA-binding domain. According to size exclusion chromatography analysis, the forkhead domain of FOXP1 existed as a mixture of monomer and dimer. The dissociation constants of the forkhead domain of wild-type, C61S, and C61Y mutants of FOXP1 were 27.3, 28.8, and 332.0 μM, respectively. In contrast, FOXP1 A39P mutant formed only a monomer. NMR analysis also showed that FOXP1 C61S and C61Y mutants existed as a mixture. The solution structure of FOXP1 A39P/C61Y mutant was similar to the X-ray structure of the FOXP2 monomer. Comparison of backbone dynamics of FOXP1 A39P/C61Y and C61Y mutants showed that the residues preceding helix 3, the hinge region, exhibited the largest conformational exchange in FOXP1 monomer. The A39 residue of FOXP1 dimer has a lower order parameter with internal motion on the ps-ns timescale, suggesting that the dynamics of the hinge region of FOXP1 are important in the formation of the swapped dimer. The analysis also showed that the residues exhibiting the motions on the ps-ns and μs-ms timescales were located at the DNA-binding surface of FOXP1, suggesting the interactions between FOXP1 and DNA may be highly dynamic.
authors.affiliation: Department of Biochemistry and Molecular Biology, National Cheng Kung University College of Medicine, Tainan, Taiwan.
authors.forename: Yuan-Ping
authors.initials: YP
authors.lastname: Chu
authors.forename: Chia-Hao
authors.initials: CH
authors.lastname: Chang
authors.forename: Jia-Hau
authors.initials: JH
authors.lastname: Shiu
authors.forename: Yao-Tsung
authors.initials: YT
authors.lastname: Chang
authors.forename: Chiu-Yueh
authors.initials: CY
authors.lastname: Chen
authors.forename: Woei-Jer
authors.initials: WJ
authors.lastname: Chuang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D013696:Temperature
chemical_list: C486626:FOXP1 protein, human; D051858:Forkhead Transcription Factors; D012097:Repressor Proteins; D012996:Solutions; D004247:DNA