title: Structural basis for RNA recognition by a dimeric PPR-protein complex.
abstract: Thylakoid assembly 8 (THA8) is a pentatricopeptide repeat (PPR) RNA-binding protein required for the splicing of the transcript of ycf3, a gene involved in chloroplast thylakoid-membrane biogenesis. Here we report the identification of multiple THA8-binding sites in the ycf3 intron and present crystal structures of Brachypodium distachyon THA8 either free of RNA or bound to two of the identified RNA sites. The apostructure reveals a THA8 monomer with five tandem PPR repeats arranged in a planar fold. The complexes of THA8 bound to the two short RNA fragments surprisingly reveal asymmetric THA8 dimers with the bound RNAs at the dimeric interface. RNA binding induces THA8 dimerization, with a conserved G nucleotide of the bound RNAs making extensive contacts with both monomers. Together, these results establish a new model of RNA recognition by RNA-induced formation of an asymmetric dimer of a PPR protein.
authors.affiliation: 1] Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, Michigan, USA. [2].
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Ke
authors.forename: Run-Ze
authors.initials: RZ
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Ban
authors.forename: X Edward
authors.initials: XE
authors.lastname: Zhou
authors.forename: Xin
authors.initials: X
authors.lastname: Gu
authors.forename: M H Eileen
authors.initials: MH
authors.lastname: Tan
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Yanyong
authors.initials: Y
authors.lastname: Kang
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Brunzelle
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
authors.forename: Karsten
authors.initials: K
authors.lastname: Melcher
authors.forename: H Eric
authors.initials: HE
authors.lastname: Xu
mesh_terms: D001665:Binding Sites; D058431:Brachypodium / Q000235:genetics* / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D007438:Introns; D008957:Models, Genetic; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D018749:RNA, Plant; D016601:RNA-Binding Proteins