This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Philippe, N.
Right arrow Articles by Schneider, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Philippe, N.
Right arrow Articles by Schneider, D.

 Previous Article  |  Next Article 

Journal of Bacteriology, February 2009, p. 909-921, Vol. 191, No. 3
0021-9193/09/$08.00+0     doi:10.1128/JB.01419-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Evolution of Penicillin-Binding Protein 2 Concentration and Cell Shape during a Long-Term Experiment with Escherichia coli{triangledown}

Nadège Philippe,1,2,{dagger} Ludovic Pelosi,1,2,{dagger},{ddagger} Richard E. Lenski,3 and Dominique Schneider1,2*

Laboratoire Adaptation et Pathogénie des Micro-organismes, Université Joseph Fourier Grenoble 1, BP 170, F-38042 Grenoble cedex 9, France,1 CNRS UMR 5163, F-38042 Grenoble Cedex 9, France,2 Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 488243

Received 9 October 2008/ Accepted 17 November 2008

Peptidoglycan is the major component of the bacterial cell wall and is involved in osmotic protection and in determining cell shape. Cell shape potentially influences many processes, including nutrient uptake as well as cell survival and growth. Peptidoglycan is a dynamic structure that changes during the growth cycle. Penicillin-binding proteins (PBPs) catalyze the final stages of peptidoglycan synthesis. Although PBPs are biochemically and physiologically well characterized, their broader effects, especially their effects on organismal fitness, are not well understood. In a long-term experiment, 12 populations of Escherichia coli having a common ancestor were allowed to evolve for more than 40,000 generations in a defined environment. We previously identified mutations in the pbpA operon in one-half of these populations; this operon encodes PBP2 and RodA proteins that are involved in cell wall elongation. In this study, we characterized the effects of two of these mutations on competitive fitness and other phenotypes. By constructing and performing competition experiments with strains that are isogenic except for the pbpA alleles, we showed that both mutations that evolved were beneficial in the environment used for the long-term experiment and that these mutations caused parallel phenotypic changes. In particular, they reduced the cellular concentration of PBP2, thereby generating spherical cells with an increased volume. In contrast to their fitness-enhancing effect in the environment where they evolved, both mutations decreased cellular resistance to osmotic stress. Moreover, one mutation reduced fitness during prolonged stationary phase. Therefore, alteration of the PBP2 concentration contributed to physiological trade-offs and ecological specialization during experimental evolution.

* Corresponding author. Mailing address: Laboratoire Adaptation et Pathogénie des Microorganismes, Institut Jean Roget, CNRS UMR5163, Université Joseph Fourier, Campus Santé, Domaine de la Merci, BP170, 38042 Grenoble Cedex 9, France. Phone: (33) 4 76 63 74 90. Fax: (33) 4 76 63 74 97. E-mail: dominique.schneider{at}ujf-grenoble.fr

{triangledown} Published ahead of print on 1 December 2008.

{dagger} N.P. and L.P. contributed equally to this study.

{ddagger} Present address: Laboratoire de Biochimie et Biophysique des Systèmes Intégrés (BBSI), Institut de Recherches en Technologies et Sciences du Vivant (iRTSV), UMR 5092 CNRS-CEA-Université Joseph Fourier (UJF), CEA-Grenoble, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9, France.

Journal of Bacteriology, February 2009, p. 909-921, Vol. 191, No. 3
0021-9193/09/$08.00+0     doi:10.1128/JB.01419-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Barrick, J.E., Lenski, R.E. (2009). Genome-wide Mutational Diversity in an Evolving Population of Escherichia coli. Cold Spring Harb Symp Quant Biol 0: sqb.2009.74.018v1-sqb.2009.74.018 [Abstract]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»