A temperature upshift induces initiation of replication at oriC on the Escherichia coli chromosome.
A temperature upshift of 10 or more degrees in the growth temperature of a bacterial culture causes induction of extra rounds of chromosome replication. This heat-induced replication (HIR) initiates at oriC, is transitory, requires RNase H1 and RecA proteins and requires neither RNA polymerase activity nor de novo protein synthesis. The number of origins activated by heat is growth rate and temperature differential dependent. An origin activation higher than 20% increases the DNA:mass ratio around twofold, and this value is kept constant for the subsequent generations of growth at 41 C. We have also shown that HIR is neither related to SDR nor induced by the heat shock response. We suggest that a thermodynamic alteration of oriC structure or of membrane fluidity could explain the observed HIR.
Botello
E
E
Department of Bioquímica, Biología Molecular y Genética, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain.
Jiménez-Sánchez
A
A
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D006358:Hot Temperature; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D056968:Lac Repressors; D010957:Plasmids; D011938:Rec A Recombinases / Q000378:metabolism; D018741:Replication Origin; D012097:Repressor Proteins / Q000235:genetics; D016914:Ribonuclease H / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D012097:Repressor Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32; D007544:Isopropyl Thiogalactoside; D011938:Rec A Recombinases; D016914:Ribonuclease H; C078856:ribonuclease HI; D012293:Rifampin