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Journal of Bacteriology, August 2007, p. 5429-5440, Vol. 189, No. 15
0021-9193/07/$08.00+0     doi:10.1128/JB.01929-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

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

Christine A. White-Ziegler,^* Amy J. Malhowski, and Sarah Young

Department of Biological Sciences and Program in Biochemistry, Smith College, Northampton, Massachusetts

Received 21 December 2006/ Accepted 15 May 2007

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.

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* Corresponding author. Mailing address: Department of Biological Sciences, Smith College, Northampton, MA 01063. Phone: (413) 585-3815. Fax: (413) 585-3786. E-mail: cwhitezi{at}smith.edu

Published ahead of print on 25 May 2007.

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Journal of Bacteriology, August 2007, p. 5429-5440, Vol. 189, No. 15
0021-9193/07/$08.00+0     doi:10.1128/JB.01929-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• White-Ziegler, C. A., Davis, T. R. (2009). Genome-Wide Identification of H-NS-Controlled, Temperature-Regulated Genes in Escherichia coli K-12. J. Bacteriol. 191: 1106-1110 [Abstract] [Full Text]  
• White-Ziegler, C. A., Um, S., Perez, N. M., Berns, A. L., Malhowski, A. J., Young, S. (2008). Low temperature (23 {degrees}C) increases expression of biofilm-, cold-shock- and RpoS-dependent genes in Escherichia coli K-12. Microbiology 154: 148-166 [Abstract] [Full Text]