Life History Traits and Genome Structure

Aerobiosis and G+C Content in Bacteria

J.R. LobryUniversité 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...]

Only Anaerobic Species

Anaerobic and Aerobic 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. LobryUniversité Claude Bernard - Lyon I

CNRS UMR 5558 & INRIA Helix

FRANCE

Bacteria in the Universal Tree of Life

PseudomonasEscherichia

Halobacterium

Methanobacterium

Desulfurococcus

Halococcus

Methanococcus

Thermoproteus

Thermus

AnacystisBacillus

Physarum

CrithidiaTetrahymena

ProrocentrumSaccharomycesOryza

Homo

Drosophila

Streptomyces

EUCARYA

ARCHAEA

EUBACTERIA« BACTERIA »

?

Only Bacteria

Bacteria and Eucarya

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. LobryUniversité Claude Bernard - Lyon I

CNRS UMR 5558 & INRIA Helix

FRANCE

Aerobiosis and G+C Content in Bacteria

AerobicAnaerobic

Naya et al. (2002) J. Mol. Evol., 55:260

Aerobiosis and G+C Content in Bacteria

AerobicAnaerobic

Naya et al. (2002) J. Mol. Evol., 55:260

Why?

Metabolic cost of amino-acids in Aerobiosis

Akashi & Gojobori (2002) PNAS, 99:3695

11.7 ATP

38.3 ATP11.7 ATP

52.0 ATP

15.3 ATP14.7 ATP

27.3 ATP

27.3 ATP

From amino-acid cost to Protein cost

Akashi & Gojobori (2002) PNAS, 99:3695

Pro

tein

cos

t in

AT

P

Protein concentration in cells

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

Aerobiosis and G+C Content in Bacteria

Life History Traits and Genome Structure

J.R. LobryUniversité Claude Bernard - Lyon I

CNRS UMR 5558 & INRIA Helix

FRANCE