The role of chaperones in the initial steps of bacterial oxidoreductase maturation

Abstract

Bacterial oxidoreductases play a key role in anaerobic respiration and represent a group of enzymes with complex maturation pathways. A group of specific chaperones, or redox enzyme maturation proteins (REMP), have an essential role in the maturation of bioenergetics enzymes. While their role has yet to be defined, REMPs have been shown to interact tightly with the amino terminal signal peptide of oxidoreductase subunits. DmsD, the REMP associated with the oxidoreductase dimethyl sulfoxide (DMSO) reductase, has been putatively shown to interact with a number of proteins. These include the general chaperones DnaK, and Trigger Factor (TF), and also include MoeB, a protein involved in the molybdenum cofactor biosynthesis. An in vitro characterization of these protein‐protein interactions will improve our understanding of the early steps of oxidoreductase maturation, as well as provide further insight into the role of REMPs. Studies to date were done using an in vitro modified far‐western technique, a robust technique that quantitatively assesses protein‐protein interactions between folded and pure proteins. An interaction was found between MoeB and DmsD, but this technique failed to show an interaction between DnaK or TF and DmsD. Alternatively, both DnaK and TF were shown to interact with the DMSO reductase signal peptide. Size exclusion chromatography is used to confirm protein‐protein interactions as well as to determine if these proteins can interact concurrently or if binding excludes one or more proteins.