Previous Article | Next Article 
Infection and Immunity, December 2009, p. 5418-5427, Vol. 77, No. 12
0019-9567/09/$08.00+0 doi:10.1128/IAI.00178-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Pyruvate Formate Lyase Is Required for Pneumococcal Fermentative Metabolism and Virulence
,
Hasan Yesilkaya,1*
Francesca Spissu,1
Sandra M. Carvalho,2
Vanessa S. Terra,1
Karen A. Homer,3
Rachel Benisty,4
Nurith Porat,4
Ana R. Neves,2 and
Peter W. Andrew1
Department of Infection, Immunity & Inflammation, University of Leicester, Leicester LE1 9HN, United Kingdom,1 Instituto de Tecnologia Química e Biologíca, Universidade Nova de Lisboa, Oeiras 2781-901, Portugal,2 Department of Microbiology, The Dental Institute, King's College London, London SE1 9RT, United Kingdom,3 Pediatric Infectious Disease Unit, Soroka University Medical Center, Faculty of Health Sciences P.O. Box 151, Beer Sheva 84101, Israel4
Received 16 February 2009/ Returned for modification 28 March 2009/ Accepted 4 September 2009
Knowledge of the in vivo physiology and metabolism of Streptococcus pneumoniae is limited, even though pneumococci rely on efficient acquisition and metabolism of the host nutrients for growth and survival. Because the nutrient-limited, hypoxic host tissues favor mixed-acid fermentation, we studied the role of the pneumococcal pyruvate formate lyase (PFL), a key enzyme in mixed-acid fermentation, which is activated posttranslationally by PFL-activating enzyme (PFL-AE). Mutations were introduced to two putative pfl genes, SPD0235 and SPD0420, and two putative pflA genes, SPD0229 and SPD1774. End-product analysis showed that there was no formate, the main end product of the reaction catalyzed by PFL, produced by mutants defective in SPD0420 and SPD1774, indicating that SPD0420 codes for PFL and SPD1774 for putative PFL-AE. Expression of SPD0420 was elevated in galactose-containing medium in anaerobiosis compared to growth in glucose, and the mutation of SPD0420 resulted in the upregulation of fba and pyk, encoding, respectively, fructose 1,6-bisphosphate aldolase and pyruvate kinase, under the same conditions. In addition, an altered fatty acid composition was detected in SPD0420 and SPD1774 mutants. Mice infected intranasally with the SPD0420 and SPD1774 mutants survived significantly longer than the wild type-infected cohort, and bacteremia developed later in the mutant cohort than in the wild type-infected group. Furthermore, the numbers of CFU of the SPD0420 mutant were lower in the nasopharynx and the lungs after intranasal infection, and fewer numbers of mutant CFU than of wild-type CFU were recovered from blood specimens after intravenous infection. The results demonstrate that there is a direct link between pneumococcal fermentative metabolism and virulence.
* Corresponding author. Mailing address: Department of Infection, Immunity & Inflammation, University of Leicester, University Road, P.O. Box 138, Leicester, LE1 9HN, United Kingdom. Phone: 00 44 116 2231556. Fax: 00 44 116 2525030. E-mail: hy3{at}le.ac.uk
Published ahead of print on 14 September 2009.
The authors have paid a fee to allow immediate free access to this article.
Infection and Immunity, December 2009, p. 5418-5427, Vol. 77, No. 12
0019-9567/09/$08.00+0 doi:10.1128/IAI.00178-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»