Influence of membrane organization on the dimerization ability of ToxR from Photobacterium profundum under high hydrostatic pressure

Abstract

High hydrostatic pressure (HHP) is suggested to influence bacterial physiology by changing the structure and function of membranes and/or integral membrane proteins. In this work, the HHP-modulated dimerization behavior of the transmembrane regulatory protein ToxR from Photobacterium profundum SS9 was investigated, in response to changes in membrane organization induced by temperature and addition of phenethyl alcohol, in a background of different organisms (Escherichia coli and P. profundum) and mutants deficient in unsaturated fatty acid synthesis. Reporter strains were constructed by chromosomal integration of an ompL-promoter lacZ fusion cassette. Arabinose-controlled ToxR expression was achieved by plasmid pBADK-ToxR-his. The results demonstrate that changes in the lipid environment have a marginal effect on the function of ToxR; instead, ToxR activity appears to be largely determined by the properties of the protein itself.

Keywords:

• ToxR
• Photobacterium profundum
• high pressure
• signalling
• membrane protein