title: Molecular mechanism of heat shock-provoked disassembly of the coliphage lambda replication complex.
abstract: We have found previously that, in contrast to the free O initiator protein of lambda phage or plasmid rapidly degraded by the Escherichia coli ClpP/ClpX protease, the lambdaO present in the replication complex (RC) is protected from proteolysis. However, in cells growing in a complete medium, a temperature shift from 30 to 43 degrees C resulted in the decay of the lambdaO fraction, which indicated disassembly of RC. This process occurred due to heat shock induction of the groE operon, coding for molecular chaperones of the Hsp60 system. Here we demonstrate that an increase in the cellular concentration of GroEL and GroES proteins is not in itself sufficient to cause RC disassembly. Another requirement is a DNA gyrase-mediated negative resupercoiling of lambda plasmid DNA, which counteracts DNA relaxation and starts to dominate 10 min after the temperature upshift. We presume that RC dissociates from lambda DNA during the negative resupercoiling, becoming susceptible to the subsequent action of GroELS and ClpP/ClpX proteins. In contrast to lambda cro+, in lambda cro- plasmid-harboring cells, the RC reveals heat shock resistance. After temperature upshift of the lambda crots plasmid-harboring cells, a Cro repressor-independent control of lambda DNA replication and heat shock resistance of RC are established before the period of DNA gyrase-mediated negative supercoiling. We suggest that the tight binding of RC to lambda DNA is due to interaction of RC with other DNA-bound proteins, and is related to the molecular basis of the lambda cro- plasmid replication control.
authors.affiliation: Laboratory of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of Sciences (University of Gdańsk).
authors.forename: A
authors.initials: A
authors.lastname: Wegrzyn
authors.forename: A
authors.initials: A
authors.lastname: Herman-Antosiewicz
authors.forename: K
authors.initials: K
authors.lastname: Taylor
authors.forename: G
authors.initials: G
authors.lastname: Wegrzyn
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism; D010582:Bacteriophage lambda / Q000254:growth & development*; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000821:virology*; D029968:Escherichia coli Proteins; D018869:Heat-Shock Response; D008957:Models, Genetic; D018832:Molecular Chaperones; D010957:Plasmids / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins; D014779:Virus Replication
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; C024013:DNA replication complex protein, Bacteriophage lambda; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities; D004250:DNA Topoisomerases, Type II