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Journal of Bacteriology, February 2008, p. 1184-1189, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01517-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Influence of the spxB Gene on Competence in Streptococcus pneumoniae{triangledown}

Patrick Bättig1* and Kathrin Mühlemann1,2

Institute for Infectious Diseases, University of Bern, Bern, Switzerland,1 University Hospital, Bern, Switzerland2

Received 20 September 2007/ Accepted 23 November 2007

In Streptococcus pneumoniae expression of pyruvate oxidase (SpxB) peaks during the early growth phase, coincident with the time of natural competence. This study investigated whether SpxB influences parameters of competence, such as spontaneous transformation frequency, expression of competence genes, and DNA release. Knockout of the spxB gene in strain D39 abolished spontaneous transformation (compared to a frequency of 6.3 x 10–6 in the parent strain [P < 0.01]). It also reduced expression levels of comC and recA as well as DNA release from bacterial cells significantly during the early growth phase, coincident with the time of spontaneous competence in the parent strain. In the spxB mutant, supplementation with competence-stimulating peptide 1 (CSP-1) restored transformation (rate, 1.8 x 10–2). This speaks against the role of SpxB as a necessary source of energy for competence. Neither supplementation with CSP-1 nor supplementation with the SpxB products H2O2 and acetate altered DNA release. Supplementation of the parent strain with catalase did not reduce DNA release significantly. In conclusion, the pneumococcal spxB gene influences competence; however, the mechanism remains elusive.

* Corresponding author. Mailing address: Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, CH-3010 Bern, Switzerland. Phone: 41 31 632 32 59. Fax: 41 31 632 87 66. E-mail: kathrin.muehlemann{at}ifik.unibe.ch

{triangledown} Published ahead of print on 7 December 2007.

Journal of Bacteriology, February 2008, p. 1184-1189, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01517-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





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