9 Properties of the Escherichia coli Heat Shock Proteins and Their Role in Bacteriophage λ Growth

Abstract

I. INTRODUCTION
The history of the discovery of the heat shock response in E. coli in the laboratories of F. Neidhardt and T. Yura, as well as its regulation, has been ably outlined in the reviews by Neidhardt et al. (1985), Neidhardt and VanBogelen (1987), and Gross et al. (this volume). In this chapter, we concentrate on (1) a description of the biochemical properties of the known heat shock proteins, (2) an analysis of the roles that the heat shock proteins play in bacteriophage λ growth, (3) a summary of the known protein-protein interactions among the heat shock proteins, and (4) a model of heat shock gene regulation, based on the known biochemical properties of the heat shock proteins.

II. KNOWN HEAT SHOCK GENES AND THEIR PRODUCTS
Of the approximately 20 E. coli heat shock proteins under Eσ³² RNA polymerase transcriptional control, the identity of ten of the corresponding genes has been established during the past few years. Surprisingly, 5 of them were previously known in a different context, because certain mutations in their corresponding genes interfered with bacteriophage λ growth (for review, see Friedman et al. 1984; Neidhardt et al. 1985; Neidhardt and VanBogelen 1987; Lindquist and Craig 1988; Gross et al., this volume). Figure 1 shows the locations on the E. coli genetic map of the ten known Eσ³²-regulated heat shock genes. In addition, the rpoH (coding for σ³²) and the htrA genes are indicated because they have been shown to belong to a new heat shock regulon,...