The role of the Cronobacter sakazakii ProP C-terminal coiled coil domain in osmotolerance

Abstract

Background: We investigate the role of the C-terminal coiled coil of the secondary proline porter ProP in contributing to Cronobacter sakazakii osmotolerance.

Findings: The extended C-terminal domain of ProP1 (encoded by ESA_02131) was spliced onto the truncated C-terminal end of ProP2 (encoded by ESA_01706); creating a chimeric protein (ProPc) which exhibits increased osmotolerance relative to the wild type.

Conclusions: It appears that the C-terminal coiled coil domain tunes ProP at low osmolality, whereas ProP transporters lacking the coiled coil domain are more active at a higher osmolality range.

Figure 1

Predicted transmembrane and tertiary structures of A) ProP2 encoded by ESA_01706, B) ProP1 encoded by ESA_02131 and C) ProPc.

Figure 2

Physiological analysis of E. coli MKH13 expressing ProP1, ProP2, ProPc and the empty pUC18 plasmid. A) Optical density was measured over a 48 hour period in media supplemented with 0-10% added NaCl. B) The growth rate of E. coli MKH13 expressing each of the proteins of interest was measured in media supplemented with 0-10% added NaCl.