Development and application of variable strength expression vectors in Shewanella oneidensis MR-1

Abstract

A suite of expression vectors was designed and constructed with modular promoter and ribosome binding site sequences resulting in a wide range of protein expression levels in S. oneidensis MR-1. To allow IPTG induction regardless of host background, a subsequent set of vectors was constructed containing lacIq, the E. coli gene encoding lac operon repressor protein. The practical application of these inducible plasmids in S. oneidensis MR-1 was demonstrated by driving variable expression of genes involved in riboflavin biosynthesis and flavin adenosine dinucleotide transport across the inner membrane in order to increase extracellular flavin levels and thus extracellular respiration rates. This study demonstrates the benefit of being able to temporally control select gene expression and amplitude of expression by using a set of predesigned vectors. The modularity of this system will enable researchers to easily exchange alternative promoters or ribosome binding sites in order to modify protein expression for custom applications.