Quantitative features of gene regulation by small RNA – Supporting Information

Here c is the concentration of sRNA-mRNA complexes, and p is the probability that degradation of the mRNA in the complex is accompanied by degradation of the sRNA. The limit p = 0 describes a catalytic mode of action, while the case p > 0 allows for mutual degradation and a non-catalytic interaction, as is the case of some endogenous E. coli small RNAs such as RyhB [1]. Assuming fast equilibration of the complex‡, namely dc/dt ' 0, we eliminate c from these equations, yielding