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TY - JOUR AU - Kawasaki, Yasuo AU - Wada, Chieko AU - Yura, Takashi PY - 1990 DA - 1990/01/01 TI - Roles of Escherichia coli heat shock proteins DnaK, DnaJ and GrpE in mini-F plasmid replication JO - Molecular and General Genetics MGG SP - 277 EP - 282 VL - 220 IS - 2 AB - A subset of Escherichia coli heat shock proteins, DnaK, DnaJ and GrpE were shown to be required for replication of mini-F plasmid. Strains of E. coli K12 carrying a missense mutation or deletion in the dnaK, dnaJ, or grpE gene were virtually unable to be transformed by mini-F DNA at the temperature (30° C) that permits cell growth. When excess amounts of the replication initiator protein (repE gene product) of mini-F were provided by means of a multicopy plasmid carrying repE, these mutant bacteria became capable of supporting mini-F replication under the same conditions. However, the copy number of a high copy number mini-F plasmid was reduced in these mutant bacteria as compared with the wild type in the presence of excess RepE protein. Furthermore, mini-F plasmid mutants that produce altered initiator protein and exhibit a very high copy number were able to replicate in strains deficient in any of the above heat shock proteins. These results indicate that the subset of heat shock proteins (DnaK, DnaJ and GrpE) play essential roles that help the functioning of the RepE initiator protein in mini-F DNA replication. SN - 1432-1874 UR - https://doi.org/10.1007/BF00260494 DO - 10.1007/BF00260494 ID - Kawasaki1990 ER -