title: Structural basis of HutP-mediated anti-termination and roles of the Mg2+ ion and L-histidine ligand.
abstract: HutP regulates the expression of the hut structural genes of Bacillus subtilis by an anti-termination mechanism and requires two components, Mg2+ ions and L-histidine. HutP recognizes three UAG triplet units, separated by four non-conserved nucleotides on the terminator region. Here we report the 1.60-A resolution crystal structure of the quaternary complex (HutP-L-histidine-Mg2+-21-base single-stranded RNA). In the complex, the RNA adopts a novel triangular fold on the hexameric surface of HutP, without any base-pairing, and binds to the protein mostly by specific protein-base interactions. The structure explains how the HutP and RNA interactions are regulated critically by the l-histidine and Mg2+ ion through the structural rearrangement. To gain insights into these structural rearrangements, we solved two additional crystal structures (uncomplexed HutP and HutP-L-histidine-Mg2+) that revealed the intermediate structures of HutP (before forming an active structure) and the importance of the Mg2+ ion interactions in the complexes.
authors.affiliation: Functional Nucleic Acids Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Thirumananseri
authors.initials: T
authors.lastname: Kumarevel
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuno
authors.forename: Penmetcha K R
authors.initials: PK
authors.lastname: Kumar
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010443:Peptide Chain Termination, Translational; D020836:Protein Structure, Quaternary; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002413:Cations, Divalent; D008024:Ligands; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D006639:Histidine; D008274:Magnesium