Borrelia burgdorferi Proteins Whose Expression Is Similarly Affected by Culture Temperature and pH

Abstract

Previously, we had demonstrated the upregulation in the expression of several proteins, including the lipoproteins OspC and P35, of Borrelia burgdorferi in the stationary growth phase. Since the expression of OspC is also known to be affected by culture temperature and pH, we examined the effects of both variables on the expression of the remaining stationary-phase-upregulated proteins. Our study revealed that the expression of each of the remaining stationary-phase-upregulated proteins, P35 included, was also influenced by culture temperature; these proteins were selectively expressed at 34°C but not at 24°C. Significantly, the expression of a majority of these proteins was also affected by culture pH, since they were abundantly expressed at pH 7.0 (resembling the tick midgut pH of 6.8 during feeding) but only sparsely at pH 8.0 (a condition closer to that of the unfed tick midgut pH of 7.4). We propose that this group of B. burgdorferi proteins, which in culture is selectively expressed under conditions of 34°C and pH 7.0, may be induced in the tick midgut during the feeding event. Furthermore, the differential and coordinate expression of these proteins under different environmental conditions suggests that the encoding genes may be coregulated.

Coordinated expression and immunogenicity of an outer membrane protein from Salmonella enterica serovar Typhi under iron limitation, oxidative stress and anaerobic conditions

“…The ability of the organism to switch on a common regulatory network suggest that there is a class of 'stress regulated' genes that are regulated by common sensing mechanism in response to different environmental signals [6,35]. The results of the present study indicating the overlapping expression of proteins under different stress conditions are in agreement with earlier studies of Chander et al [21] and Ramamoorthy and Schoel-Meeker [36]. The results suggest that expression of proteins does not depend on single environmental stimulus in host but there may be an interaction among stimuli.…”

Borrelia burgdorferi RevA Antigen Is a Surface-Exposed Outer Membrane Protein Whose Expression Is Regulated in Response to Environmental Temperature and pH

“…We and others have previously observed that some spirochete proteins involved in mammalian infection are regulated by temperature, with greater amounts of protein synthesized by bacteria cultivated at temperatures similar to the mammalian body temperature than by bacteria grown at ambient temperature (17,31,38,46,51,54,55,62). For these reasons, we examined the levels of RevA protein synthesized by bacteria cultivated at either 23 or 34°C.…”

“…Since the production of some B. burgdorferi proteins preferentially synthesized during infection of warm-blooded animals are also regulated by pH (12,13,46,62), we examined the effect of culture medium pH on RevA expression. Significantly higher levels of RevA were produced by bacteria cultivated in medium buffered to remain at pH 7.0 than by those grown in medium having a pH of 8.0 (Fig.…”

Genetic Variation at thevlsELocus ofBorrelia burgdorferiwithin Ticks and Mice over the Course of a Single Transmission Cycle

“…We propose that the vlsE locus falls into the growing category of Borrelia genes that are preferentially expressed in the host and not the vector (10,13). Several studies have identified temperature and pH as signals that regulate the expression of Borrelia genes (7,8,28,35,39). These signals are likely to play a role during natural transmission, because spirochetes experience an increase in temperature and decrease in pH as they move from the vector to the vertebrate.…”