title: Structures of the T. brucei kRNA editing factor MRB1590 reveal unique RNA-binding pore motif contained within an ABC-ATPase fold.
abstract: Kinetoplastid RNA (kRNA) editing is a process that creates translatable mitochondrial mRNA transcripts from cryptogene encoded RNAs and is unique for kinetoplastids, such as Trypanosoma brucei. In addition to the catalytic 20S editosome, multiple accessory proteins are required for this conversion. Recently, the multiprotein mitochondrial RNA binding complex 1 (MRB1) has emerged as a key player in this process. MRB1 consists of six core proteins but makes dynamic interactions with additional accessory proteins. Here we describe the characterization of one such factor, the 72 kDa MRB1590 protein. In vivo experiments indicate a role for MRB1590 in editing mitochondrial mRNA transcripts, in particular the transcript encoding the ATP synthase subunit 6 (A6). Structural studies show that MRB1590 is dimeric and contains a central ABC-ATPase fold embedded between novel N- and C-terminal regions. The N-terminal domains combine to create a basic pore and biochemical studies indicate residues in this region participate in RNA binding. Structures capturing distinct MRB1590 conformations reveal that the RNA binding pore adopts closed and open states, with the latter able to accommodate RNA. Based on these findings, implications for MRB1590 function are discussed.
authors.affiliation: Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: Porsha L R
authors.initials: PL
authors.lastname: Shaw
authors.affiliation: Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, NY, USA.
authors.forename: Natalie M
authors.initials: NM
authors.lastname: McAdams
authors.affiliation: Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hast
authors.affiliation: Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, NY, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Ammerman
authors.affiliation: Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, NY, USA.
authors.forename: Laurie K
authors.initials: LK
authors.lastname: Read
authors.affiliation: Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA maria.schumacher@duke.edu.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Schumacher
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism; D020816:Amino Acid Motifs; D001665:Binding Sites; D002460:Cell Line; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D011072:Poly U / Q000737:chemistry; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D012313:RNA / Q000378:metabolism*; D017393:RNA Editing; D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000235:genetics*
chemical_list: D009711:Nucleotides; D015800:Protozoan Proteins; D000077278:RNA, Mitochondrial; D016053:RNA, Protozoan; D016601:RNA-Binding Proteins; D011072:Poly U; D000244:Adenosine Diphosphate; D012313:RNA; D000251:Adenosine Triphosphatases