title: Two singular types of CCCH tandem zinc finger in Nab2p contribute to polyadenosine RNA recognition.
abstract: The seven C-terminal CCCH-type zinc fingers of Nab2p bind the poly(A) tail of mRNA (∼A25). Using NMR, we demonstrated that the first four (Zf1-Zf4) contain two structurally independent tandems (TZF12 and TZF34) and bind A12 with moderate affinity (KD = 2.3 μM). Nab2p TZF12 contains a long α helix that contacts the zinc fingers Zf1 and Zf2 to arrange them similarly to Zf6-7 in the Nab2p Zf5-7 structure. Nab2p TZF34 exhibits a distinctive two-fold symmetry of the zinc centers with mutual recognition of histidine ligands. Our mutagenesis and NMR data demonstrate that the α helix of TZF12 and Zf3 of TZF34 define the RNA-binding interface, while Zf1, Zf2, and Zf4 seem to be excluded. These results further our understanding of polyadenosine RNA recognition by the CCCH domain of Nab2p. Moreover, we describe a hypothetical mechanism for controlling poly(A) tail length with specific roles for TZF12, TZF34, and Zf5-7 domains.
authors.affiliation: Department of Biological Physical Chemistry, Instituto de Química-Física "Rocasolano," CSIC, Serrano 119, 28006 Madrid, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Martínez-Lumbreras
authors.forename: Clara M
authors.initials: CM
authors.lastname: Santiveri
authors.forename: Yasmina
authors.initials: Y
authors.lastname: Mirassou
authors.forename: Silvia
authors.initials: S
authors.lastname: Zorrilla
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Pérez-Cañadillas
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D017124:Conserved Sequence; D056831:Coordination Complexes / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry* / Q000235:genetics; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D040681:Structural Homology, Protein; D013816:Thermodynamics; D016335:Zinc Fingers
chemical_list: D056831:Coordination Complexes; C080773:NAB2 protein, S cerevisiae; D029543:Nucleocytoplasmic Transport Proteins; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins