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Translational Coupling and Regulation in Prokaryotic Operons

Lon Chubiz, Chemical and Biomolecular Engineering, University of Illinois, 600 South Matthews Ave., 211 Roger Adams Laboratory, Box C-3, Urbana, IL 61801 and Christopher V. Rao, Department of Chemical and Biomolecular Engineering, University of Illinois, 600 South Matthews Ave., 211 Roger Adams Laboratory, Box C-3, Urbana, IL 61801.

The operon is the fundamental transcriptional unit in bacteria. In the most general terms, an operon is a collection of genes transcribed on the same mRNA strand. Typically, the genes within an operon are associated with common cellular processes such as a metabolic pathway. It has been observed experimentally that the numbers of the proteins expressed from a given operon are not equal. Developing predictive models for bacterial cellular processes requires a detailed knowledge of the stoichiometry of the protein components within an operon. Moreover, having predictive capability for protein expression in operons will facilitate the introduction of novel, non-native cellular processes into bacterial hosts, allowing for applications in pharmaceutical and biochemical production. In this work, we explore the role of translational coupling as a mechanism for controlling the differential expression of proteins within a operon using a combination of computational and experimental approaches. We demonstrate how translational coupling can be used to control the relative stoichiometry of protein expression and as a mechanism to attenuate the effect of translational noise.