Lambda Xis degradation in vivo by Lon and FtsH.
Lambda Xis, which is required for site-specific excision of phage lambda from the bacterial chromosome, has a much shorter functional half-life than Int, which is required for both integration and excision (R. A. Weisberg and M. E. Gottesman, p. 489-500, in A. D. Hershey, ed., The Bacteriophage Lambda, 1971). We found that Xis is degraded in vivo by two ATP-dependent proteases, Lon and FtsH (HflB). Xis was stabilized two- to threefold more than in the wild type in a lon mutant and as much as sixfold more in a lon ftsH double mutant at the nonpermissive temperature for the ftsH mutation. Integration of lambda into the bacterial chromosome was delayed in the lon ftsH background, suggesting that accumulation of Xis in vivo interferes with integration. Overexpression of Xis in wild-type cells from a multicopy plasmid inhibited integration of lambda and promoted curing of established lysogens, confirming that accumulation of Xis interferes with the ability of Int to establish and maintain an integrated prophage.
Leffers
G G
GG
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892-4255, USA.
Gottesman
S
S
D049069:ATP-Dependent Proteases; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D010582:Bacteriophage lambda / Q000235:genetics / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008242:Lysogeny / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D049070:Protease La; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D014764:Viral Proteins; D004254:DNA Nucleotidyltransferases; C063911:excisionase; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La