Sidiqi, M.; Wilce, J.A.; Vivian, J.P.; Porter, C.J.; Barker, A.; Leedman, P.J.; Wilce, M.C.J.
Structure and RNA binding of the third KH domain of poly(C)-binding protein 1
NUCLEIC ACIDS RESEARCH, 33:1213-1221, 2005

Poly(C)-binding proteins (CPs) are important regulators of mRNA stability and translational regulation. They recognize C-richRNA through their triple KH (hn RNP K homology) domain structures and are thought to carry out their function though direct protection of mRNA sites as well as through interactions with other RNA-binding proteins. We report the crystallographically derived structure of the third domain of alpha CP1 to 2.1 angstrom resolution. alpha CP1-KH3 assumes a classical type I KH domain fold with a triple-stranded beta-sheet held against a three-helix cluster in a beta alpha alpha beta beta alpha configuration. Its binding affinity to an RNA sequence from the 3'-untranslated region (3'-UTR) of androgen receptor mRNA was determined using surface plasmon resonance, giving a K-d of 4.37 mu M, which is indicative of intermediate binding. A model of alpha CP1- KH3 with poly(C)-RNA was generated by homology to a recently reported RNA-bound KH domain structure and suggests the molecular basis for oligonucleotide binding and poly(C)-RNA specificity.

DOI:10.1093/nar/gki265

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