title: The histone-like H protein of Escherichia coli is ribosomal protein S3.
abstract: We report the purification of four proteins from Escherichia coli that stimulate or inhibit inter- and/or intramolecular recombination promoted by the yeast plasmid-encoded FLP protein. The proteins are identified as the ribosomal proteins S3 (27 kDa), L2 (26 kDa), S4 (24 kDa), and S5 (16 kDa), on the basis of N-terminal sequence analysis. The S3 protein is found to be identical to H protein, an E. coli histone-like protein that is related to histone H2A immunologically and by virtue of amino acid content. The H protein/S3 identity is based on co-migration on polyacrylamide gels, heat stability, amino acid analysis, and effects on FLP-promoted recombination. These results are relevant to current studies on the structure of the E. coli nucleoid. Since the H protein has previously been found associated with the E. coli nucleoid, the results indicate that either (a) some ribosomal proteins serve a dual function in E. coli, or, more likely, (b) ribosomal proteins can and are being mis-identified as nucleoid constituents.
authors.affiliation: Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706.
authors.forename: R C
authors.initials: RC
authors.lastname: Bruckner
authors.forename: M M
authors.initials: MM
authors.lastname: Cox
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology*; D002876:Chromosomes, Bacterial / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology*; D006657:Histones / Q000502:physiology; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D012269:Ribosomal Proteins / Q000302:isolation & purification / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D006657:Histones; D012269:Ribosomal Proteins; C044152:ribosomal protein S3