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Infection and Immunity, September 2008, p. 4038-4045, Vol. 76, No. 9
0019-9567/08/$08.00+0     doi:10.1128/IAI.00477-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

An Iron-Binding Protein, Dpr, Decreases Hydrogen Peroxide Stress and Protects Streptococcus pyogenes against Multiple Stresses{triangledown}

Chih-Cheng Tsou,1 Chuan Chiang-Ni,1 Yee-Shin Lin,2 Woei-Jer Chuang,3 Ming-T. Lin,6 Ching-Chuan Liu,4 and Jiunn-Jong Wu1,5*

Institute of Basic Medical Sciences,1 Departments of Microbiology and Immunology,2 Biochemistry,3 Pediatrics,4 Medical Laboratory Science and Biotechnology,5 College of Medicine, National Cheng Kung University, Tainan, and Institute of Medical Science, Medical College, Tzu Chi University, Hualien, Taiwan6

Received 17 April 2008/ Returned for modification 19 May 2008/ Accepted 27 May 2008

Streptococcus pyogenes does not produce catalase, but it can grow in aerobic environments and survive in the presence of peroxide. One of the stress proteins of this organism, peroxide resistance protein (Dpr), has been studied to examine its role in resistance to hydrogen peroxide, but the protective mechanism of Dpr is not clear. The aim of this study was to characterize the dpr gene and its role in dealing with different stresses. A dpr deletion mutant was constructed by double-crossover mutagenesis. The dpr mutant was more sensitive to H2O2, and complementation could partially restore the defect in the mutant. Pretreatment with the iron chelator deferoxamine mesylate rescued the survival activity of the mutant under oxidative stress conditions. The dpr mutant also showed a low survival rate in the long-term stationary phase, when it was treated with extreme acids, and under alkaline pH conditions compared to the wild-type strain. The growth of the dpr mutant was slower than that of the wild-type strain in iron-limiting conditions. The dpr mutant showed high sensitivity to iron and zinc but not to manganese, copper, nickel, and calcium. Recombinant Dpr protein was purified and showed iron-binding activity, whereas no DNA-binding activity was found. These data indicate that an iron-binding protein, Dpr, provides protection from hydrogen peroxide stress by preventing the Fenton reaction, and Dpr was identified as a novel stress protein that protects against several stresses in group A streptococci.

* Corresponding author. Mailing address: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan, Taiwan 701. Phone: 886-6-2353535, ext. 5775. Fax: 886-6-2363956. E-mail: jjwu{at}mail.ncku.edu.tw

{triangledown} Published ahead of print on 9 June 2008.

Editor: A. J. Bäumler

Infection and Immunity, September 2008, p. 4038-4045, Vol. 76, No. 9
0019-9567/08/$08.00+0     doi:10.1128/IAI.00477-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





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