A Theoretical Lower Bound for Selection on the Expression Levels of Proteins.
We use simple models of the costs and benefits of microbial gene expression to show that changing a protein's expression away from its optimum by 2-fold should reduce fitness by at least [Formula: see text], where P is the fraction the cell's protein that the gene accounts for. As microbial genes are usually expressed at above 5 parts per million, and effective population sizes are likely to be above 10(6), this implies that 2-fold changes to gene expression levels are under strong selection, as [Formula: see text], where Ne is the effective population size and s is the selection coefficient. Thus, most gene duplications should be selected against. On the other hand, we predict that for most genes, small changes in the expression will be effectively neutral.
Environmental Genomics and Systems Biology, Lawrence Berkeley National Lab morgannprice@yahoo.com.
Morgan N
MN
Price
Environmental Genomics and Systems Biology, Lawrence Berkeley National Lab.
Adam P
AP
Arkin
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D056084:Genetic Fitness; D008957:Models, Genetic; D009154:Mutation; D012641:Selection, Genetic
D001426:Bacterial Proteins
gene expression levels; metabolic models; microbiology