Anchoring of DNA to the bacterial cytoplasmic membrane through cotranscriptional synthesis of polypeptides encoding membrane proteins or proteins for export: a mechanism of plasmid hypernegative supercoiling in mutants deficient in DNA topoisomerase I.
A homologous set of plasmids expressing tet, lacY, and melB, genes encoding integral cytoplasmic membrane proteins, and tolC and ampC, genes encoding proteins for export through the cytoplasmic membrane, was constructed for studying the effects of transcription and translation of such genes on the hypernegative supercoiling of plasmids in Escherichia coli cells deficient in DNA topoisomerase I. The results support the view that intracellular bacterial DNA is anchored to the cytoplasmic membrane at many points through cotranscriptional synthesis of membrane proteins or proteins designated for export across the cytoplasmic membrane; in the latter case, the presence of the signal peptide appears to be unnecessary for cotranscriptional membrane association.
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
A S
AS
Lynch
J C
JC
Wang
D001483:Base Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D004278:DNA, Superhelical; D008565:Membrane Proteins; D004264:DNA Topoisomerases, Type I