ClpB is the Escherichia coli heat shock protein F84.1

J Bacteriol. 1991 Jul;173(14):4254-62. doi: 10.1128/jb.173.14.4254-4262.1991.

Abstract

ClpB is thought to be involved in proteolysis because of its sequence similarity to the ClpA subunit of the ClpA-ClpP protease. It has recently been shown that ClpP is a heat shock protein. Here we show that ClpB is the Escherichia coli heat shock protein F84.1. The F84.1 protein was overproduced in strains containing the clpB gene on a plasmid and was absent from two-dimensional gels from a clpB null mutation. Besides possessing a slower growth rate at 44 degrees C, the null mutant strain had a higher rate of death at 50 degrees C. We used reverse transcription of in vivo mRNA to show that the clpB gene was expressed from a sigma 32-specific promoter consensus sequence at both 37 and 42 degrees C. We noted that the clpB+ gene also caused the appearance of a second protein spot, F68.5, on two-dimensional gels. This spot was approximately 147 amino acids smaller than F84.1 and most probably is the result of a second translational start on the clpB mRNA. F68.5 can be observed on many published two-dimensional gels of heat-induced E. coli proteins, but the original catalog of 17 heat shock proteins did not include this spot.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Endopeptidase Clp
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Escherichia coli Proteins*
  • Genes, Bacterial*
  • Genotype
  • Heat-Shock Proteins / genetics*
  • Hot Temperature
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Oligonucleotide Probes
  • Plasmids
  • Promoter Regions, Genetic
  • Restriction Mapping
  • Sequence Homology, Nucleic Acid

Substances

  • Escherichia coli Proteins
  • Heat-Shock Proteins
  • Oligonucleotide Probes
  • Endopeptidase Clp
  • ClpB protein, E coli

Associated data

  • GENBANK/M29364
  • GENBANK/M74477
  • GENBANK/M74478
  • GENBANK/M74479
  • GENBANK/M74480
  • GENBANK/M74481
  • GENBANK/M74482
  • GENBANK/M74483
  • GENBANK/M74484
  • GENBANK/S39977