title: Escherichia coli ribosomal protein S1 has two polynucleotide binding sites.
abstract: The interaction of Escherichia coli ribosomal protein S1 with a variety of RNA and DNA oligomers and polymers has been studied, using both a sedimentation technique and the quenching of intrinsic protein fluorescence upon nucleic acid binding to obtain equilibrium binding parameters. Two polynucleotide binding sites have been detected on S1: site I binds either single-stranded DNA or RNA and does not discriminate between adenine- and cytidine-containing polynucleotides, while the II binding is highly specific for RNA over DNA and shows a marked preference for cytidine polynucleotides over the corresponding adenine-containing species. On the basis of the binding properties of S1 to denatured DNA cellulose and poly(rC)-cellulose, it is demonstrated that every S1 molecule carries both a site I and a site II. Some possible implications of these results for mechanisms of protein synthesis and phage Qbeta replication are briefly considered.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D011119:Polynucleotides / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011119:Polynucleotides; D012329:RNA, Bacterial; D012269:Ribosomal Proteins