Nab2p is an essential protein involved in mRNP (messenger ribonucleoprotein particles) formation and export in Saccharomyces cerevisiae. Its specific poly(A) RNA recognition ability resides on a region containing 7 CCCH-type zinc finger domains, of which, the last three zinc finger structure was previously known. In our group, we have solved the NMR structure of the first 4 zinc fingers that show novel elements in their fold. The first two zinc fingers (Zf1 and Zf2) form a compact tandem stabilized by a new -helix contacting both. Zf3 and Zf4 form a second tandem in which the metallic centres associate in a singular symmetric way with mutual recognition of the Zn²⁺ coordinating histidines. NMR, fluorescence anisotropy and mutagenesis studies identify the -helix in the first tandem and the exposed surface of Zf3 as the RNA binding interface. Our results allow us to propose a recognition model where Nab2p Zf1-4 cooperates with Nab2p Zf5-7 to reconstitute the poly(A) binding profile of the full-length protein.

Reference

Two Singular Types of CCCH Tandem Zinc Finger in Nab2p Contribute to Polyadenosine RNA Recognition.

Martínez-Lumbreras S^1,3, Santiveri CM^2,3, Mirassou Y¹, Zorrilla S^1,2, Pérez-Cañadillas JM¹*.

Structure. 2013 Aug 28. doi: 10.1016/j.str.2013.07.019.

1 IQFR-CSIC; 2 CIB-CSIC; 3 equal contribution;*corresponding author