title: The RRM domain of human fused in sarcoma protein reveals a non-canonical nucleic acid binding site.
abstract: Fused in sarcoma (FUS) is involved in many processes of RNA metabolism. FUS and another RNA binding protein, TDP-43, are implicated in amyotrophic lateral sclerosis (ALS). It is significant to characterize the RNA recognition motif (RRM) of FUS as its nucleic acid binding properties are unclear. More importantly, abolishing the RNA binding ability of the RRM domain of TDP43 was reported to suppress the neurotoxicity of TDP-43 in Drosophila. The sequence of FUS-RRM varies significantly from canonical RRMs, but the solution structure of FUS-RRM determined by NMR showed a similar overall folding as other RRMs. We found that FUS-RRM directly bound to RNA and DNA and the binding affinity was in the micromolar range as measured by surface plasmon resonance and NMR titration. The nucleic acid binding pocket in FUS-RRM is significantly distorted since several critical aromatic residues are missing. An exceptionally positively charged loop in FUS-RRM, which is not found in other RRMs, is directly involved in the RNA/DNA binding. Substituting the lysine residues in the unique KK loop impaired the nucleic acid binding and altered FUS subcellular localization. The results provide insights into the nucleic acid binding properties of FUS-RRM and its potential relevance to ALS.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.
authors.forename: Xuehui
authors.initials: X
authors.lastname: Liu
authors.forename: Chunyan
authors.initials: C
authors.lastname: Niu
authors.forename: Jintao
authors.initials: J
authors.lastname: Ren
authors.forename: Jiayu
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xie
authors.forename: Haining
authors.initials: H
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Weimin
authors.initials: W
authors.lastname: Gong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009696:Nucleic Acids / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance
chemical_list: D009696:Nucleic Acids; D016601:RNA-Binding Proteins