title: NMR studies of Arc repressor mutants: proton assignments, secondary structure, and long-range contacts for the thermostable proline-8----leucine variant of Arc.
abstract: Arc repressor is a 53-residue sequence-specific DNA binding protein. We report the assignment of the proton NMR spectrum and the secondary structure for the thermostable PL8 variant of Arc. This mutant, which differs from wild type by a Pro-8----Leu substitution, was chosen for study because its enhanced stability allows spectra to be acquired at elevated temperatures where spectral resolution is higher. The first five residues of the protein play important roles in DNA binding but appear to be disordered in solution. Residues 6-14 form the remaining part of the N-terminal DNA binding region of the protein and assume an antiparallel beta-conformation. This indicates that Arc is a member of a new class of DNA binding proteins. The observed interresidue nuclear Overhauser effects are consistent with a beta-strand, gamma-turn, beta-strand structure for the residue 6-14 region, although other structures are also consistent with the data. The remaining portion of the protein is predominantly alpha-helical. Residues 16-26 and 35-50 form amphipathic alpha-helices which may pack together in a four-helix bundle in the protein dimer.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
authors.forename: M G
authors.initials: MG
authors.lastname: Zagorski
authors.forename: J U
authors.initials: JU
authors.lastname: Bowie
authors.forename: A K
authors.initials: AK
authors.lastname: Vershon
authors.forename: R T
authors.initials: RT
authors.lastname: Sauer
authors.forename: D J
authors.initials: DJ
authors.lastname: Patel
mesh_terms: D000595:Amino Acid Sequence; D001330:Electronic Data Processing; D007930:Leucine; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009154:Mutation; D011392:Proline; D011487:Protein Conformation; D012097:Repressor Proteins / Q000235:genetics; D012483:Salmonella Phages / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D011392:Proline; D007930:Leucine