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SUMMARY:Contributed Talk 6: Carbon source-dependent metabolic costs of ami
 no acid biosynthesis in Escherichia coli - Waschina\, S (Max-Planck-Instit
 ut fr Chemische kologie)
DTSTART:20141028T151500Z
DTEND:20141028T153000Z
UID:TALK55738@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Co-authors: Glen D'Souza (Experimental Ecology and Evolution R
 esearch Group\, Max Planck Institute for Chemical Ecology)\, Christian Kos
 t (Experimental Ecology and Evolution Research Group\, Max Planck Institut
 e for Chemical Ecology)\, Christoph Kaleta (Theoretical Systems Biology Re
 search Group\, FSU Jena) \n\nBacteria invest a significant proportion of t
 heir available energy and resources into the biosynthesis of amino acids\,
  which are required for cell growth and maintenance. As a consequence\, th
 e costs of amino acid biosynthesis profoundly limit the growth rate and\, 
 hence\, the fitness of a bacterial species. Despite the substantial role f
 or the metabolic economics of a cell\, little is known about how these cos
 ts may shape the dynamics of cooperative cross-feeding interactions in bac
 terial communities. Here we show that the growth rates of Escherichia coli
  amino acid auxotrophic strains relative to the growth rate of the E. coli
  wild type are strongly carbon source-dependent\, when amino acid availabi
 lity is limiting. To understand these differences we developed a computati
 onal framework to quantitatively estimate biosynthetic costs of amino acid
  anabolism. This approach is based on a genome-scale metabolic network of 
 E. coli and essentially estimates the amount of a given carbon source whic
 h is needed to synthesize a specific amino acid. The observed carbon sourc
 e-dependent increase of the auxotroph's maximum growth rate max with incre
 asing amino acid concentration correlated positively with the predicted bi
 osynthetic costs. We conclude that the differences in the increase of max 
 are due to the metabolic costs\, which the auxotrophs save by taking up th
 e focal amino acid from the environment. These findings imply that there i
 s a high potential for mutualistic amino acid cross-feeding interactions t
 o evolve among sympatric populations of the same bacterial species that sp
 ecialize in the utilization of different substrates when multiple carbon s
 ources are available in the environment.\n
LOCATION:Seminar Room 1\, Newton Institute
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