Functional characterization of naturally occurring genetic variations of the human guanine-rich RNA sequence binding factor 1 (GRSF1)

• Published in: Biochimica et biophysica acta. General subjects Vol. 1862; no. 4; pp. 866 - 876
• Main Authors: Sofi, Sajad, Fitzgerald, Julia C., Jähn, Désirée, Dumoulin, Bernhard, Stehling, Sabine, Kuhn, Hartmut, Ufer, Christoph
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2018
• Subjects: alleles; Amino Acid Motifs - genetics; Amino Acid Sequence; amino acids; Binding Sites; crystal structure; gel electrophoresis; genetic databases; Genetic variation; hnRNP F/H; homozygosity; Humans; Kinetics; metabolism; mitochondrial RNA; Models, Molecular; mutants; Mutation; nuclear magnetic resonance spectroscopy; nucleotide sequences; Poly(A)-Binding Proteins - chemistry; Poly(A)-Binding Proteins - genetics; Poly(A)-Binding Proteins - metabolism; Protein Binding; Protein Domains; protein structure; ribonucleoproteins; RNA - chemistry; RNA - genetics; RNA - metabolism; RNA recognition motif; RNA-binding; RNA-binding proteins; Sequence Homology, Amino Acid; Thermostability; Thermostability; hnRNP F/H; Genetic variation; RNA-binding; RNA recognition motif
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2017.12.008

The guanine-rich RNA sequence binding factor 1 (GRSF1) constitutes an ubiquitously occurring RNA-binding protein (RBP), which belongs to the family of heterogeneous nuclear ribonucleoprotein F/H (hnRNP F/H). It has been implicated in nuclear, cytosolic and mitochondrial RNA metabolism. Although the crystal structures of GRSF1 orthologs have not been solved, amino acid alignments with similar RNA-binding proteins suggested the existence of three RNA-binding domains designated quasi-RNA recognition motifs (qRRMs). Here we established 3D–models for the three qRRMs of human GRSF1 on the basis of the NMR structure of hnRNP F and identified the putative RNA interacting amino acids. Next, we explored the genetic variability of the three qRRMs of human GRSF1 by searching genomic databases and tested the functional consequences of naturally occurring mutants. For this purpose the RNA-binding capacity of wild-type and mutant recombinant GRSF1 protein species was assessed by quantitative RNA electrophoretic mobility shift assays. We found that some of the naturally occurring GRSF1 mutants exhibited a strongly reduced RNA-binding activity although the general protein structure was hardly affected. These data suggested that homozygous allele carriers of these particular mutants express dysfunctional GRSF1 and thus may show defective GRSF1 signaling. •3D structure models of GRSF1 qRRMs indicate presence of canonical RRM fold•Genetic variations severely reduce RNA-binding activity of GRSF1 in vitro•RNA-binding is affected by geometry and chemistry of amino acid side chains