title: The molecular recognition of kink-turn structure by the L7Ae class of proteins.
abstract: L7Ae is a member of a protein family that binds kink-turns (k-turns) in many functional RNA species. We have solved the X-ray crystal structure of the near-consensus sequence Kt-7 of Haloarcula marismortui bound by Archaeoglobus fulgidus L7Ae at 2.3-Å resolution. We also present a structure of Kt-7 in the absence of bound protein at 2.2-Å resolution. As a result, we can describe a general mode of recognition of k-turn structure by the L7Ae family proteins. The protein makes interactions in the widened major groove on the outer face of the k-turn. Two regions of the protein are involved. One is an α-helix that enters the major groove of the NC helix, making both nonspecific backbone interactions and specific interactions with the guanine nucleobases of the conserved G • A pairs. A hydrophobic loop makes close contact with the L1 and L2 bases, and a glutamate side chain hydrogen bonds with L1. Taken together, these interactions are highly selective for the structure of the k-turn and suggest how conformational selection of the folded k-turn occurs.
authors.forename: Lin
authors.initials: L
authors.lastname: Huang
authors.forename: David M J
authors.initials: DM
authors.lastname: Lilley
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry*; D019611:Archaeoglobus fulgidus / Q000737:chemistry*; D020029:Base Pairing; D001483:Base Sequence; D018360:Crystallography, X-Ray; D019614:Haloarcula marismortui / Q000235:genetics*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D019642:RNA, Archaeal / Q000737:chemistry*; D012269:Ribosomal Proteins / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins; D019642:RNA, Archaeal; D012269:Ribosomal Proteins
keywords: RNA structure; RNA-protein recognition; X-ray crystallography; k-turn motif