The Enigma of Oxygen Intolerance in Campylobacter Jejuni: An Integrative Transcriptomic, Proteomic and Physiological Approach

Campylobacter jejuni is a microaerophile which requires oxygen for growth, but is unable to grow at normal atmospheric oxygen tensions. The molecular bases for oxygen inhibition of growth on the one hand, and an oxygen requirement on the other, are very poorly understood in this pathogen. One problem that confounds comparative studies at a range of oxygen tensions in batch cultures is changes in growth rate and other cellular parameters that will have secondary effects on gene expression. <P>
In this project we propose to use defined chemostat cultures of Campylobacter jejuni, which will be carbon-limited at a constant growth rate, in which the oxygen tension can be varied to establish a series of steady-states. These will be sampled to determine any differences in gene and protein expression, using a combined transcriptomic and proteomic approach. Because cells are derived from cultures at the same growth rate, we will be able to ensure that changes that we observe are due to the influence of oxygen. Comparative changes in the activities of the respiratory chains and key metabolic enzymes will be compared with these results, in order to test hypotheses concerning the oxygen sensitivity of this pathogen. We are thus particularly interested in genes and proteins, which show significant up- or down- regulation/activity at oxygen tensions above that for optimum growth (yield) and these will be subjected to mutagenesis, phenotypic and proteomic analysis. <P>The aim is to obtain an accurate picture of the molecular responses of this important pathogen to changes in oxygen. (Joint with BB/E014429/1)