Abstract
Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane. In this study, we have analyzed the thermal adaptation in two closely related respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica Although B. pertussis represents a pathogen strictly adapted to the human body temperature, B. bronchiseptica causes infection in a broad range of animals and survives also outside of the host. We applied GC-MS to determine the fatty acids of both Bordetella species grown at different temperatures and analyzed the membrane fluidity by fluorescence anisotropy measurement. In parallel, we also monitored the effect of growth temperature changes on the expression and production of several virulence factors. In response to low temperatures, B. pertussis adapted its fatty acid composition and membrane fluidity to a considerably lesser extent when compared with B. bronchiseptica Remarkably, B. pertussis maintained the production of virulence factors at 24 °C, whereas B. bronchiseptica cells resumed the production only upon temperature upshift to 37 °C. This growth temperature-associated differential modulation of virulence factor production was linked to the phosphorylation state of transcriptional regulator BvgA. The observed differences in low-temperature adaptation between B. pertussis and B. bronchiseptica may result from selective adaptation of B. pertussis to the human host. We propose that the reduced plasticity of the B. pertussis membranes ensures sustained production of virulence factors at suboptimal temperatures and may play an important role in the transmission of the disease.
Highlights
Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane
We propose that the reduced plasticity of the B. pertussis membranes ensures sustained production of virulence factors at suboptimal temperatures and may play an important role in the transmission of the disease
We have determined membrane phospholipid fatty acid (FA) composition of B. pertussis Tohama I and B. bronchiseptica RB50 cells grown at 37 °C
Summary
Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane. B. pertussis represents a pathogen strictly adapted to the human body temperature, B. bronchiseptica causes infection in a broad range of animals and survives outside of the host. In response to low temperatures, B. pertussis adapted its fatty acid composition and membrane fluidity to a considerably lesser extent when compared with B. bronchiseptica. B. pertussis maintained the production of virulence factors at 24 °C, whereas B. bronchiseptica cells resumed the production only upon temperature upshift to 37 °C. Change in the ambient temperature is one of the major stresses that bacteria face as it, among other effects, influences the fluidity of their plasma membrane and function of the cell envelope [1]. Temperature-dependent regulation of fatty acid synthesis allows cells to maintain the appropriate fluidity of the membrane regardless of the ambient temperature [9, 10].
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