Cellular nucleic acid binding protein binds G-rich single-stranded nucleic acids and may function as a nucleic acid chaperone.
Cellular nucleic acid binding protein (CNBP) is a small single-stranded nucleic acid binding protein made of seven Zn knuckles and an Arg-Gly rich box. CNBP is strikingly conserved among vertebrates and was reported to play broad-spectrum functions in eukaryotic cells biology. Neither its biological function nor its mechanisms of action were elucidated yet. The main goal of this work was to gain further insights into the CNBP biochemical and molecular features. We studied Bufo arenarum CNBP (bCNBP) binding to single-stranded nucleic acid probes representing the main reported CNBP putative targets. We report that, although bCNBP is able to bind RNA and single-stranded DNA (ssDNA) probes in vitro, it binds RNA as a preformed dimer whereas both monomer and dimer are able to bind to ssDNA. A systematic analysis of variant probes shows that the preferred bCNBP targets contain unpaired guanosine-rich stretches. These data expand the knowledge about CNBP binding stoichiometry and begins to dissect the main features of CNBP nucleic acid targets. Besides, we show that bCNBP presents a highly disordered predicted structure and promotes the annealing and melting of nucleic acids in vitro. These features are typical of proteins that function as nucleic acid chaperones. Based on these data, we propose that CNBP may function as a nucleic acid chaperone through binding, remodeling, and stabilizing nucleic acids secondary structures. This novel CNBP biochemical activity broadens the field of study about its biological function and may be the basis to understand the diverse ways in which CNBP controls gene expression.
Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Dpto. de Ciencias Biológicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina.
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D020121:5' Untranslated Regions / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002022:Bufo arenarum; D015342:DNA Probes / Q000737:chemistry / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000737:chemistry / Q000378:metabolism; D054856:G-Quadruplexes; D018507:Gene Expression Regulation, Developmental; D006151:Guanosine / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D014176:Protein Biosynthesis; D015347:RNA Probes / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis / Q000378:metabolism; D016335:Zinc Fingers
D020121:5' Untranslated Regions; C433227:CNBP protein, human; D015342:DNA Probes; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D018832:Molecular Chaperones; D015347:RNA Probes; D016601:RNA-Binding Proteins; D006151:Guanosine