Shifts in growth strategies reflect tradeoffs in cellular economics

Mol Syst Biol. 2009;5:323. doi: 10.1038/msb.2009.82. Epub 2009 Nov 3.

Abstract

The growth rate-dependent regulation of cell size, ribosomal content, and metabolic efficiency follows a common pattern in unicellular organisms: with increasing growth rates, cell size and ribosomal content increase and a shift to energetically inefficient metabolism takes place. The latter two phenomena are also observed in fast growing tumour cells and cell lines. These patterns suggest a fundamental principle of design. In biology such designs can often be understood as the result of the optimization of fitness. Here we show that in basic models of self-replicating systems these patterns are the consequence of maximizing the growth rate. Whereas most models of cellular growth consider a part of physiology, for instance only metabolism, the approach presented here integrates several subsystems to a complete self-replicating system. Such models can yield fundamentally different optimal strategies. In particular, it is shown how the shift in metabolic efficiency originates from a tradeoff between investments in enzyme synthesis and metabolic yields for alternative catabolic pathways. The models elucidate how the optimization of growth by natural selection shapes growth strategies.

MeSH terms

  • Animals
  • Cell Growth Processes*
  • Cells / metabolism*
  • Models, Biological
  • Recombinant Proteins / metabolism
  • Substrate Specificity

Substances

  • Recombinant Proteins