The Bicarbonate Transporter Is Essential for Bacillus anthracis Lethality

PLoS Pathogens

James A. Hoch¹  Magali Soyer¹  Marta Perego¹  Adam C. Wilson¹ 

[1] The Scripps Research Institute, Department of Molecular and Experimental Medicine, Division of Cellular Biology, La Jolla, California, United States of America

关键词: Bicarbonates;    Bacillus anthracis;    Toxins;    Carbon dioxide;    Gene expression;    Virulence factors;    Animal models of infection;    Mouse models;   

DOI  :  10.1371/journal.ppat.1000210

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

In the pathogenic bacterium Bacillus anthracis, virulence requires induced expression of the anthrax toxin and capsule genes. Elevated CO2/bicarbonate levels, an indicator of the host environment, provide a signal ex vivo to increase expression of virulence factors, but the mechanism underlying induction and its relevance in vivo are unknown. We identified a previously uncharacterized ABC transporter (BAS2714-12) similar to bicarbonate transporters in photosynthetic cyanobacteria, which is essential to the bicarbonate induction of virulence gene expression. Deletion of the genes for the transporter abolished induction of toxin gene expression and strongly decreased the rate of bicarbonate uptake ex vivo, demonstrating that the BAS2714-12 locus encodes a bicarbonate ABC transporter. The bicarbonate transporter deletion strain was avirulent in the A/J mouse model of infection. Carbonic anhydrase inhibitors, which prevent the interconversion of CO2 and bicarbonate, significantly affected toxin expression only in the absence of bicarbonate or the bicarbonate transporter, suggesting that carbonic anhydrase activity is not essential to virulence factor induction and that bicarbonate, and not CO2, is the signal essential for virulence induction. The identification of this novel bicarbonate transporter essential to virulence of B. anthracis may be of relevance to other pathogens, such as Streptococcus pyogenes, Escherichia coli, Borrelia burgdorferi, and Vibrio cholera that regulate virulence factor expression in response to CO2/bicarbonate, and suggests it may be a target for antibacterial intervention.

【 授权许可】

CC BY