title: Structure and Mechanism of Dimer-Monomer Transition of a Plant Poly(A)-Binding Protein upon RNA Interaction: Insights into Its Poly(A) Tail Assembly.
abstract: Poly(A)-binding proteins (PABPs) play crucial roles in mRNA biogenesis, stability, transport and translational control in most eukaryotic cells. Although animal PABPs are well-studied proteins, the biological role, three-dimensional structure and RNA-binding mode of plant PABPs remain largely uncharacterized. Here, we report the structural features and RNA-binding mode of a Citrus sinensis PABP (CsPABPN1). CsPABPN1 has a domain architecture of nuclear PABPs (PABPNs) with a single RNA recognition motif (RRM) flanked by an acidic N-terminus and a GRPF-rich C-terminus. The RRM domain of CsPABPN1 displays virtually the same three-dimensional structure and poly(A)-binding mode of animal PABPNs. However, while the CsPABPN1 RRM domain specifically binds poly(A), the full-length protein also binds poly(U). CsPABPN1 localizes to the nucleus of plant cells and undergoes a dimer-monomer transition upon poly(A) interaction. We show that poly(A) binding by CsPABPN1 begins with the recognition of the RNA-binding sites RNP1 and RNP2, followed by interactions with residues of the β2 strands, which stabilize the dimer, thus leading to dimer dissociation. Like human PABPN1, CsPABPN1 also seems to form filaments in the presence of poly(A). Based on these data, we propose a structural model in which contiguous CsPABPN1 RRM monomers wrap around the RNA molecule creating a superhelical structure that could not only shield the poly(A) tail but also serve as a scaffold for the assembly of additional mRNA processing factors.
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Mariane Noronha
authors.initials: MN
authors.lastname: Domingues
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Mauricio Luis
authors.initials: ML
authors.lastname: Sforça
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Adriana Santos
authors.initials: AS
authors.lastname: Soprano
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, Durham, County Durham DH1, United Kingdom.
authors.forename: Jack
authors.initials: J
authors.lastname: Lee
authors.affiliation: Instituto Carlos Chagas, Fundação Oswaldo Cruz, Curitiba, PR CEP81350-010, Brazil.
authors.forename: Tatiana de Arruda Campos Brasil
authors.initials: TACB
authors.lastname: de Souza
authors.affiliation: Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Cassago
authors.affiliation: Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Rodrigo Villares
authors.initials: RV
authors.lastname: Portugal
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: de Mattos Zeri
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Mario Tyago
authors.initials: MT
authors.lastname: Murakami
authors.affiliation: School of Biological and Biomedical Sciences, Durham University, Durham, County Durham DH1, United Kingdom.
authors.forename: Ari
authors.initials: A
authors.lastname: Sadanandom
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil.
authors.forename: Paulo Sergio Lopes
authors.initials: PSL
authors.lastname: de Oliveira
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP CP6192, Brazil. Electronic address: celso.benedetti@lnbio.cnpem.br.
authors.forename: Celso Eduardo
authors.initials: CE
authors.lastname: Benedetti
mesh_terms: D000595:Amino Acid Sequence; D032084:Citrus sinensis / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D039102:Poly(A)-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D017386:Sequence Homology, Amino Acid
chemical_list: D010940:Plant Proteins; D039102:Poly(A)-Binding Proteins; D018749:RNA, Plant; D016601:RNA-Binding Proteins
keywords: Citrus sinensis; CsPABPN1; RRM domain; dimer–monomer transition; poly(A)-binding protein