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Life History Traits and Genome Structure Aerobiosis and G+C Content in Bacteria J.R. Lobry Université Claude Bernard - Lyon I CNRS UMR 5558 & INRIA Helix FRANCE Aerobic versus Anaerobic • You need the presence of O2 to live, you are aerobic (obligate) • You need the absence of O2 to live, you are anaerobic (obligate) • [...snip...] Anaerobic and Aerobic Species Only Anaerobic Species Aerobic >> Anaerobic • In aerobic conditions (with O2) the oxydation of one molecule of glucose (respiration) yields 38 ATP (metabolic currency unit). Short generation times. • In anaerobic conditions (without O2) the fermentation of one molecule of glucose yields 2 ATP (metabolic currency unit). Long generation times. The generation time is a life history trait Life History Traits and Genome Structure Aerobiosis and G+C Content in Bacteria J.R. Lobry Université Claude Bernard - Lyon I CNRS UMR 5558 & INRIA Helix FRANCE Bacteria in the Universal Tree of Life EUCARYA Oryza Drosophila Homo Saccharomyces Prorocentrum Tetrahymena Crithidia Physarum ARCHAEA Halococcus Halobacterium Methanococcus ? Methanobacterium Desulfurococcus Thermoproteus EUBACTERIA Escherichia Pseudomonas Thermus Streptomyces Anacystis Bacillus « BACTERIA » Bacteria and Eucarya Only Bacteria Bacterial Genomes: Circular dsDNA Here G+C = 50% The G+C content is a genome structure Life History Traits and Genome Structure Aerobiosis and G+C Content in Bacteria J.R. Lobry Université Claude Bernard - Lyon I CNRS UMR 5558 & INRIA Helix FRANCE Aerobiosis and G+C Content in Bacteria Anaerobic Aerobic Naya et al. (2002) J. Mol. Evol., 55:260 Aerobiosis and G+C Content in Bacteria Anaerobic Why? Aerobic Naya et al. (2002) J. Mol. Evol., 55:260 Metabolic cost of amino-acids in Aerobiosis 38.3 ATP 11.7 ATP 52.0 ATP 11.7 ATP 27.3 ATP 14.7 ATP 15.3 ATP 27.3 ATP Akashi & Gojobori (2002) PNAS, 99:3695 Protein cost in ATP From amino-acid cost to Protein cost Protein concentration in cells Akashi & Gojobori (2002) PNAS, 99:3695 So what? The growth of genomic data But available fossil DNA is < 0.00013 109 years... All data are here Dataset • ~300 bacterial species • ~1,000,000 proteins • ~100,000,000 amino-acids Akashi (2002) Naya (2002) Interpretation Aerobic bacteria have a higher genomic G+C content than anerobic bacteria because this induces an average protein composition which is less expensive in aerobic conditions Life History Traits and Genome Structure Aerobiosis and G+C Content in Bacteria J.R. Lobry Université Claude Bernard - Lyon I CNRS UMR 5558 & INRIA Helix FRANCE