title: DNA recognition by beta-sheets in the Arc repressor-operator crystal structure.
abstract: Transcription of the ant gene during lytic growth of bacteriophage P22 (ref. 1) is regulated by the cooperative binding of two Arc repressor dimers to a 21-base-pair operator site. Here we report the co-crystal structure of this Arc tetramer-operator complex at 2.6 A resolution. As expected from genetic and structural studies and from the co-crystal structure of the homologous Escherichia coli MetJ repressor, each Arc dimer uses an antiparallel beta-sheet to recognize bases in the major groove. However, the Arc and MetJ complexes differ in several important ways: the beta-sheet-DNA interactions of Arc are far less symmetrical; DNA binding by Arc is accompanied by important conformational changes in the beta-sheet; and Arc uses a different part of its protein surface for dimer-dimer interactions.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: B E
authors.initials: BE
authors.lastname: Raumann
authors.forename: M A
authors.initials: MA
authors.lastname: Rould
authors.forename: C O
authors.initials: CO
authors.lastname: Pabo
authors.forename: R T
authors.initials: RT
authors.lastname: Sauer
mesh_terms: D001483:Base Sequence; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D017433:Protein Structure, Secondary; D012097:Repressor Proteins / Q000737:chemistry*; D014764:Viral Proteins / Q000737:chemistry*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D004247:DNA