NMR structure of the three quasi RNA recognition motifs (qRRMs) of human hnRNP F and interaction studies with Bcl-x G-tract RNA: a novel mode of RNA recognition.
The heterogeneous nuclear ribonucleoprotein (hnRNP) F belongs to the hnRNP H family involved in the regulation of alternative splicing and polyadenylation and specifically recognizes poly(G) sequences (G-tracts). In particular, hnRNP F binds a G-tract of the Bcl-x RNA and regulates its alternative splicing, leading to two isoforms, Bcl-x(S) and Bcl-x(L), with antagonist functions. In order to gain insight into G-tract recognition by hnRNP H members, we initiated an NMR study of human hnRNP F. We present the solution structure of the three quasi RNA recognition motifs (qRRMs) of hnRNP F and identify the residues that are important for the interaction with the Bcl-x RNA by NMR chemical shift perturbation and mutagenesis experiments. The three qRRMs exhibit the canonical betaalphabetabetaalphabeta RRM fold but additional secondary structure elements are present in the two N-terminal qRRMs of hnRNP F. We show that qRRM1 and qRRM2 but not qRRM3 are responsible for G-tract recognition and that the residues of qRRM1 and qRRM2 involved in G-tract interaction are not on the beta-sheet surface as observed for the classical RRM but are part of a short beta-hairpin and two adjacent loops. These regions define a novel interaction surface for RNA recognition by RRMs.
Dominguez
Cyril
C
Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland.
Allain
Frédéric H-T
FH
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D024322:Amino Acids, Aromatic / Q000235:genetics; D001665:Binding Sites; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019906:Nuclear Magnetic Resonance, Biomolecular; D011068:Poly G / Q000737:chemistry; D011485:Protein Binding; D012313:RNA / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D051020:bcl-X Protein / Q000235:genetics*
D024322:Amino Acids, Aromatic; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D051020:bcl-X Protein; D011068:Poly G; D012313:RNA