Species barrier to RNA recognition overcome with nonspecific RNA binding domains.
We show here that nonspecific RNA-protein interactions can significantly enhance the biological activity of an essential RNA. protein complex. Bacterial glutaminyl-tRNA synthetase poorly aminoacylates yeast tRNA and, as a consequence, cannot rescue a knockout allele of the gene for the yeast homologue. In contrast to the bacterial protein, the yeast enzyme has an extra appended domain at the N terminus. Previously, we showed that fusion of this yeast-specific domain to the bacterial protein enabled it to function as a yeast enzyme in vivo and in vitro. We suggested that the novel yeast-specific domain contributed to RNA interactions in a way that compensated for the poor fit between the yeast tRNA and bacterial enzyme. Here we establish that the novel appended domain by itself binds nonspecifically to different RNA structures. In addition, we show that fusion of an unrelated yeast protein, Arc1p, to the bacterial enzyme also converts it into a functional yeast enzyme in vivo and in vitro. A small C-terminal segment of Arc1p is necessary and sufficient for this conversion. This segment was shown by others to have nonspecific tRNA binding properties. Thus, nonspecific RNA binding interactions in general can compensate for barriers to formation of a specific and essential RNA.protein complex.
Wang
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The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Schimmel
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D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D012329:RNA, Bacterial / Q000378:metabolism*; D012331:RNA, Fungal / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity
C102145:ARC1 protein, S cerevisiae; D012329:RNA, Bacterial; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; C020659:glutaminyl-tRNA synthetase