The activity of sigma 32 is reduced under conditions of excess heat shock protein production in Escherichia coli.

The expression of heat shock genes in Escherichia coli is controlled by the action of an alternate sigma-factor of RNA polymerase, sigma 32, which directs core RNA polymerase to recognize the promoters for heat shock genes. After a shift from 30 degrees C to 42 degrees C, both the level of sigma 32 and transcription initiation at heat shock promoters transiently increase, indicating that heat shock gene expression is regulated by changes in the concentration of sigma 32. Here, we report that heat shock gene expression is regulated by changes in the activity of sigma 32 under some conditions. Our results show that the transient repression of heat shock protein synthesis, which follows a shift down from 42 degrees C to 30 degrees, occurs as a result of decreased transcription initiation at heat shock promoters, but this repression is accompanied by only a small decrease in the level of sigma 32. In addition, the induction of heat shock proteins following overproduction of sigma 32 from a multicopy plasmid is only transient, despite the fact that the level of sigma 32 remains elevated. Constitutive overproduction of sigma 32 also fails to cause a proportionate increase in heat shock gene transcription. These three examples suggest that the activity of sigma 32 is reduced under conditions of excess heat shock gene expression.

[1]  F. Neidhardt,et al.  Positive regulatory gene for temperature-controlled proteins in Escherichia coli. , 1981, Biochemical and biophysical research communications.

[2]  R. Burgess,et al.  Rapid micromethod for the purification of Escherichia coli ribonucleic acid polymerase and the preparation of bacterial extracts active in ribonucleic acid synthesis , 1976, Journal of bacteriology.

[3]  H. Echols,et al.  Specialized nucleoprotein structures at the origin of replication of bacteriophage lambda. Protein association and disassociation reactions responsible for localized initiation of replication. , 1989, The Journal of biological chemistry.

[4]  G. Lorimer,et al.  GroE heat-shock proteins promote assembly of foreign prokaryotic ribulose bisphosphate carboxylase oligomers in Escherichia coli , 1989, Nature.

[5]  C. Gross,et al.  Consensus sequence for Escherichia coli heat shock gene promoters. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[6]  F. Neidhardt,et al.  In vitro effect of the Escherichia coli heat shock regulatory protein on expression of heat shock genes , 1986, Journal of bacteriology.

[7]  K. Ito,et al.  Transient shut off of Escherichia coli heat shock protein synthesis upon temperature shift down. , 1989, Biochemical and biophysical research communications.

[8]  T. Yamamori,et al.  Genetic control of heat-shock protein synthesis and its bearing on growth and thermal resistance in Escherichia coli K-12. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[9]  G. Walker,et al.  Defect in expression of heat-shock proteins at high temperature in xthA mutants , 1986, Journal of bacteriology.

[10]  R. Burgess,et al.  The operen that encodes the sigma subunit of RNA polymerase also encodes ribosomal protein S21 and DNA primase in E. coli K12 , 1983, Cell.

[11]  F. Neidhardt,et al.  Levels of major proteins of Escherichia coli during growth at different temperatures , 1979, Journal of bacteriology.

[12]  D. Court,et al.  Induction of the heat shock response of E. coli through stabilization of sigma 32 by the phage lambda cIII protein. , 1987, Genes & development.

[13]  D. Court,et al.  A system to study promoter and terminator signals recognized by Escherichia coli RNA polymerase. , 1981, Gene amplification and analysis.

[14]  F. Neidhardt,et al.  Transient rates of synthesis of individual polypeptides in E. coli following temperature shifts , 1978, Cell.

[15]  F. Neidhardt,et al.  Escherichia Coli and Salmonella: Typhimurium Cellular and Molecular Biology , 1987 .

[16]  N. Brot,et al.  Correlation between the 32-kDa sigma factor levels and in vitro expression of Escherichia coli heat shock genes. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[17]  A. Grossman,et al.  The htpR gene product of E. coli is a sigma factor for heat-shock promoters , 1984, Cell.

[18]  A. Berk,et al.  Spliced early mRNAs of simian virus 40. , 1978, Proceedings of the National Academy of Sciences of the United States of America.

[19]  N. Thompson,et al.  Studies of the role of the Escherichia coli heat shock regulatory protein sigma 32 by the use of monoclonal antibodies. , 1987, The Journal of biological chemistry.

[20]  S. Kessler.  Use of protein A-bearing staphylococci for the immunoprecipitation and isolation of antigens from cells. , 1981, Methods in enzymology.

[21]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[22]  C. Gross,et al.  Isolation and characterization of Escherichia coli mutants that lack the heat shock sigma factor sigma 32 , 1988, Journal of bacteriology.

[23]  A. Grossman,et al.  Sigma 32 synthesis can regulate the synthesis of heat shock proteins in Escherichia coli. , 1987, Genes & development.

[24]  C. Georgopoulos,et al.  Role of the Escherichia coli DnaK and DnaJ heat shock proteins in the initiation of bacteriophage lambda DNA replication. , 1988, Proceedings of the National Academy of Sciences of the United States of America.