title: Model Uracil-Rich RNAs and Membrane Protein mRNAs Interact Specifically with Cold Shock Proteins in Escherichia coli.
abstract: Are integral membrane protein-encoding mRNAs (MPRs) different from other mRNAs such as those encoding cytosolic mRNAs (CPRs)? This is implied from the emerging concept that MPRs are specifically recognized and delivered to membrane-bound ribosomes in a translation-independent manner. MPRs might be recognized through uracil-rich segments that encode hydrophobic transmembrane helices. To investigate this hypothesis, we designed DNA sequences encoding model untranslatable transcripts that mimic MPRs or CPRs. By utilizing in vitro-synthesized biotinylated RNAs mixed with Escherichia coli extracts, we identified a highly specific interaction that takes place between transcripts that mimic MPRs and the cold shock proteins CspE and CspC, which are normally expressed under physiological conditions. Co-purification studies with E. coli expressing 6His-tagged CspE or CspC confirmed that the specific interaction occurs in vivo not only with the model uracil-rich untranslatable transcripts but also with endogenous MPRs. Our results suggest that the evolutionarily conserved cold shock proteins may have a role, possibly as promiscuous chaperons, in the biogenesis of MPRs.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Daniel
authors.initials: D
authors.lastname: Benhalevy
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Elena S
authors.initials: ES
authors.lastname: Bochkareva
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ido
authors.initials: I
authors.lastname: Biran
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Eitan
authors.initials: E
authors.lastname: Bibi
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D057773:Cold Shock Proteins and Peptides / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding; D012329:RNA, Bacterial / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014498:Uracil / Q000378:metabolism*
chemical_list: D057773:Cold Shock Proteins and Peptides; D012329:RNA, Bacterial; D012333:RNA, Messenger; D014498:Uracil