IbpA and IbpB, the new heat-shock proteins, bind to endogenous Escherichia coli proteins aggregated intracellularly by heat shock.

Abstract

IbpA/B, 16 kDa heat-shock proteins were recently described as recognizing heterologous protein inclusion bodies in Escherichia coli cells; the corresponding genes formed an operon regulated by the rpoH gene product, sigma 32 protein (Burland et al (1993) Genomics 16, 551; Allen et al (1992) J Bacteriol 174, 6938; Chuang et al (1993) Gene 134, 1; Chuang and Blattner (1993) J Bacteriol 175, 5242). We have found that IbpA/Bs also recognize endogenous bacterial proteins aggregated intracellularly by heat shock. IbpA/B proteins were isolated and purified from the aggregates (the S fraction), identified by amino acid microsequencing and used as immunogen for anti-IbpA/B serum preparation. Western blotting with the serum showed that in cells growing at 30 degrees C IbpA/B were located in the bacterial outer membrane and appeared in the S fraction after heat shock. Then the cellular level of the IbpA/B proteins increased about 20-fold as estimated by densitometry of the Western blots. In the E coli rpoH strain the level of IbpA/B was higher than in wild type before the heat shock and rose to still higher levels after it. This result pointed to a regulation of ibpA/B operon by another factor, besides that of sigma 32.

• Authors: E Laskowska, A Wawrzynów, A Taylor
• Journal: Biochimie (Biochimie) Vol. 78 Issue 2 Pg. 117-22 ( 1996) ISSN: 0300-9084 [Print] France
• PMID: 8818220 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Escherichia coli Proteins
• Heat-Shock Proteins
• IbpA protein, E coli
• IbpB protein, E coli

Topics

• Bacterial Proteins (metabolism)
• Cell Aggregation
• Cell Fractionation
• Electrophoresis, Polyacrylamide Gel
• Escherichia coli
• Escherichia coli Proteins
• Heat-Shock Proteins (metabolism)
• Inclusion Bodies (metabolism)
• Isoelectric Focusing
• Molecular Weight