Two Singular Types of Ccch Tandem Zinc Finger in Nab2P Contribute to Polyadenosine RNA Recognition.
Martinez-Lumbreras, S., Santiveri, C.M., Mirassou, Y., Zorrilla, S., Perez-Canadillas, J.M.(2013) Structure 21: 1800
- PubMed: 23994011 
- DOI: https://doi.org/10.1016/j.str.2013.07.019
- Primary Citation of Related Structures:  
3ZJ1, 3ZJ2 - PubMed 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.
Organizational Affiliation: 
Department of Biological Physical Chemistry, Instituto de Química-Física "Rocasolano," CSIC, Serrano 119, 28006 Madrid, Spain.