Human Body Temperature (37°C) Increases the Expression of Iron, Carbohydrate, and Amino Acid Utilization Genes in Escherichia coli K-12

Abstract

Using DNA microarrays, we identified 126 genes in Escherichia coli K-12 whose expression is increased at human body temperature (37°C) compared to growth at 23°C. Genes involved in the uptake and utilization of amino acids, carbohydrates, and iron dominated the list, supporting a model in which temperature serves as a host cue to increase expression of bacterial genes needed for growth. Using quantitative real-time PCR, we investigated the thermoregulatory response for representative genes in each of these three categories (hisJ, cysP, srlE, garP, fes, and cirA), along with the fimbrial gene papB. Increased expression at 37°C compared to 23°C was retained in both exponential and stationary phases for all of the genes and in most of the various media tested, supporting the relative importance of this cue in adapting to changing environments. Because iron acquisition is important for both growth and virulence, we analyzed the regulation of the iron utilization genes cirA and fes and found that growth in iron-depleted medium abrogated the thermoregulatory effect, with high-level expression at both temperatures, contrasting with papB thermoregulation, which was not greatly altered by limiting iron levels. A positive role for the environmental regulator H-NS was found for fes, cirA, hisJ, and srlE transcription, whereas it had a primarily negative effect on cysP and garP expression. Together, these studies indicate that temperature is a broadly used cue for regulating gene expression in E. coli and that H-NS regulates iron, carbohydrate, and amino acid utilization gene expression.

Hha Controls Escherichia coli O157:H7 Biofilm Formation by Differential Regulation of Global Transcriptional Regulators FlhDC and CsgD

“…Tempera-ture was one of the first environmental cues recognized to affect the expression of global regulatory cascades that redirect bacterial cells to form biofilms by upregulating production of curli and extracellular polysaccharides along with bacterial cell surface-associated proteins and nucleic acids (19,24,(30)(31)(32)(33)(34)(35)(36). The selective expression of desired sets of genes in response to temperature cues is a common theme among commensal and pathogenic bacterial species for conserving energy and ensuring their survival and persistence in a specific niche as well as transmission to a new host or locale (28,29,37). A recent study comparing the global gene expression profiles of E. coli K-12 grown at 37°C or 30°C showed elevated expression of metabolic pathways, such as uptake and utilization of amino acids, carbohydrates, and iron needed for rapid growth at 37°C (29).…”

“…For example, flagellar genes are expressed under conditions favoring rapid growth and expression of curli is enhanced during slow growth or stationary phase, nutritional deprivation, low temperature, low osmolarity, and oxidative stress (26)(27)(28)(29)(30). Tempera-ture was one of the first environmental cues recognized to affect the expression of global regulatory cascades that redirect bacterial cells to form biofilms by upregulating production of curli and extracellular polysaccharides along with bacterial cell surface-associated proteins and nucleic acids (19,24,(30)(31)(32)(33)(34)(35)(36).…”

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

“…One aspect contributing to this mismatch was that the simple nature of these solutions was not appropriate as already discussed. Another aspect was that the temperature was below the human body temperature of 37°C [101]. This is significant as an increase in temperature is associated with increased chemical activity, due to the increase in kinetic energy that is afforded from the increased temperature.…”

Glucose-Dependent Activation ofBacillus anthracisToxin Gene Expression and Virulence Requires the Carbon Catabolite Protein CcpA

“…Investigations into bacterial pathogenesis have revealed an intuitive connection between basic metabolic processes of adaptation and virulence. For example, it has been reported that bacteria alter the transcription of carbohydrate utilization genes and virulence factor-encoding genes in response to the sugar availability encountered in the environment, in particular, in the infected host (44,65,67,69,79). Consequently, regulatory mechanisms that connect carbohydrate metabolism to virulence factor production must have evolved.…”