title: The properties of the RNA-binding protein NF90 are considerably modulated by complex formation with NF45.
abstract: Nuclear factor 90 (NF90) is an RNA-binding protein (RBP) that regulates post-transcriptionally the expression of various mRNAs. NF90 was recently shown to be capable of discriminating between different RNA substrates. This is mediated by an adaptive and co-operative interplay between three RNA-binding motifs (RBMs) in the protein's C-terminus. In many cell types, NF90 exists predominantly in a complex with NF45. Here, we compared the RNA-binding properties of the purified NF90 monomer and the NF90-NF45 heterodimer by biophysical and biochemical means, and demonstrate that the interaction with NF45 considerably affects the characteristics of NF90. Along with a thermodynamic stabilization, complex formation substantially improves the RNA-binding capacity of NF90 by modulating its binding mode and by enhancing its affinity for single- and double-stranded RNA substrates. Our data suggest that features of both the N- and C-termini of NF90 participate in the heterodimerization with NF45 and that the formation of NF90-NF45 changes the conformation of NF90's RBMs to a status in which the co-operative interplay of the RBMs is optimal. NF45 is considered to act as a conformational scaffold for NF90's RBMs, which alters the RNA-binding specificity of NF90. Accordingly, the monomeric NF90 and the NF90-NF45 heterodimer may exert different functions in the cell.
authors.affiliation: Institute of Biochemistry and Biotechnology (NFI), Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Schmidt
authors.affiliation: Institute of Biochemistry and Biotechnology (NFI), Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Knick
authors.affiliation: Section Protein Biochemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany.
authors.forename: Hauke
authors.initials: H
authors.lastname: Lilie
authors.affiliation: Institute of Biochemistry and Biotechnology (NFI), Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany.
authors.forename: Susann
authors.initials: S
authors.lastname: Friedrich
authors.affiliation: Institute of Biochemistry and Biotechnology (NFI), Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany.
authors.forename: Ralph Peter
authors.initials: RP
authors.lastname: Golbik
authors.affiliation: Institute of Biochemistry and Biotechnology (NFI), Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle/Saale, Germany sven.behrens@biochemtech.uni-halle.de.
authors.forename: Sven-Erik
authors.initials: SE
authors.lastname: Behrens
mesh_terms: D020816:Amino Acid Motifs; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D051903:Nuclear Factor 45 Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D050779:Nuclear Factor 90 Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D012330:RNA, Double-Stranded / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: C494013:ILF2 protein, human; C429643:ILF3 protein, human; D051903:Nuclear Factor 45 Protein; D050779:Nuclear Factor 90 Proteins; D009841:Oligonucleotides; D012330:RNA, Double-Stranded; D011994:Recombinant Proteins
keywords: RBP; RGG; RNA–protein interactions; dsRBM; posttranscriptional regulation