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Protein costs do not explain evolution of metabolic strategies and regulation of ribosomal content: does protein investment explain an anaerobic bacterial Crabtree effect?

Goel, A., Eckhardt, T. H., Puri, P., de Jong, A., Branco dos Santos, F., Giera, M., Fusetti, F., de Vos, W. M., Kok, J., Poolman, B., Molenaar, D., Kuipers, O. P. & Teusink, B. Jul-2015 In : Molecular Microbiology. 97, 1, p. 77-92 16 p.

Research output: Scientific - peer-reviewArticle

Protein investment costs are considered a major driver for the choice of alternative metabolic strategies. We tested this premise in Lactococcus lactis, a bacterium that exhibits a distinct, anaerobic version of the bacterial Crabtree/Warburg effect; with increasing growth rates it shifts from a high yield metabolic mode [mixed-acid fermentation; 3 adenosine triphosphate (ATP) per glucose] to a low yield metabolic mode (homolactic fermentation; 2 ATP per glucose). We studied growth rate-dependent relative transcription and protein ratios, enzyme activities, and fluxes of L.lactis in glucose-limited chemostats, providing a high-quality and comprehensive data set. A three- to fourfold higher growth rate rerouted metabolism from acetate to lactate as the main fermentation product. However, we observed hardly any changes in transcription, protein levels and enzyme activities. Even levels of ribosomal proteins, constituting a major investment in cellular machinery, changed only slightly. Thus, contrary to the original hypothesis, central metabolism in this organism appears to be hardly regulated at the level of gene expression, but rather at the metabolic level. We conclude that L.lactis is either poorly adapted to growth at low and constant glucose concentrations, or that protein costs play a less important role in fitness than hitherto assumed.

Original languageEnglish
Pages (from-to)77-92
Number of pages16
JournalMolecular Microbiology
Volume97
Issue number1
StatePublished - Jul-2015

    Keywords

  • LACTOCOCCUS-LACTIS IL1403, PYRUVATE-FORMATE-LYASE, ESCHERICHIA-COLI, STREPTOCOCCUS-LACTIS, SACCHAROMYCES-CEREVISIAE, TRANSCRIPTOME ANALYSIS, OVERFLOW METABOLISM, CHEMOSTAT CULTURES, GENE-EXPRESSION, FLUX ANALYSIS

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