Proteome analysis of the Escherichia coli heat shock response under steady-state conditions

Abstract

In this study a proteomic approach was used to investigate the steady-state response of Escherichia coli to temperature up-shifts in a cascade of two continuously operated bioreactors. The first reactor served as cell source with optimal settings for microbial growth, while in the second chemostat the cells were exposed to elevated temperatures. By using this reactor configuration, which has not been reported to be used for the study of bacterial stress responses so far, it is possible to study temperature stress under well-defined, steady-state conditions. Specifically the effect on the cellular adaption to temperature stress using two-dimensional gel electrophoresis was examined and compared at the cultivation temperatures of 37°C and 47.5°C. As expected, the steady-state study with the double bioreactor configuration delivered a different protein spectrum compared to that obtained with standard batch experiments in shaking flasks and bioreactors. Setting a high cut-out spot-to-spot size ratio of 5, proteins involved in defence against oxygen stress, functional cell envelope proteins, chaperones and proteins involved in protein biosynthesis, the energy metabolism and the amino acid biosynthesis were found to be differently expressed at high cultivation temperatures. The results demonstrate the complexity of the stress response in a steady-state culture not reported elsewhere to date.

Physiological and Proteomic Analysis of Escherichia coli Iron-Limited Chemostat Growth

“…Combining the defined, reproducible steady-state chemostat culturing conditions with 2-DE proteomics is especially powerful for discovering microbial metabolic responses to stresses. For instance, this combination of methods has been used to study the E. coli response to carbon limitation (39), heat shock (36), and phage predation survival (40).…”

Differential proteome analysis of a selected bacterial strain isolated from a high background radiation area in response to radium stress

“…However, the OmpA of E. coli showed a down-regulation at high cultivation temperatures. Synthesis of OmpA is growth rate dependent and this envelop stress could cause an extremely reduced growth [20].…”

The renaissance of continuous culture in the post-genomics age

“…It is interesting to recall that physiological states of this sort were being investigated in the early days of continuous culture using simple single stage chemostats [182]; the Porton group established glycerol-and ammonium-limited cultures of Aerobacter (now Enterobacter) aerogenes achieving a minimum specific growth rate of 0.004 h -1 (NB this required 1,250 h of chemostat cultivation and, thereby, very rigorous instrument reliability). The second study is of a familiar phenomenon, heat shock response, but employing temperature up-shifts in the second of a two-stage chemostat system enabling, the authors opine, the study of temperature stress under well-defined steady state conditions [116]. Proteome analyses revealed that proteins involved in the defence against oxygen stress, functional cell envelopes, chaperones, protein and amino acid biosyntheses, and energy metabolism were differently expressed at high cultivation temperatures, and that the patterns (not surprisingly) differed from those when E. coli was grown under batch conditions.…”

“…Knijnenburg et al [104] Proteome expression in Shewanella oneidensis Elias et al [56] Physiology: transition state behaviour Proteomics of heat-shocked E. coli in 2-stage chemostats Luders et al [116] SFP1 and nutrient-dependent regulation of yeast ribosome biogenesis and cell size Cipollina et al [38] Bioenergetics of yeast during glucose ? galactose transitions van der Brink et al [189] Metabolic studies Definition of a Zn-specific regulon in yeast involved in storage carbohydrate metabolism…”