A synthetic system for expression of components of a bacterial microcompartment

In general, prokaryotes are considered to be single-celled organisms that lack internal membrane-bound organelles. However, many bacteria produce proteinaceous microcompartments that serve a similar purpose; that is to concentrate specific enzymatic reactions together or to shield the wider cytoplasm from toxic metabolic intermediates. In this work, a synthetic operon encoding the key structural components of a microcompartment was designed based on the genes for the Salmonella propanediol utilisation (Pdu) microcompartment. The genes chosen included pduA, -B, -J, -K, -N, -T, and -U, and each were shown to produce protein in an Escherichia coli chassis. In parallel, a set of compatible vectors designed to express non-native cargo proteins were also designed and tested. Engineered hexa-Histidine tags allowed isolation of the components of the microcompartments together with co-expressed, untagged, cargo proteins. Finally, an in vivo protease accessibility assay suggested that a PduD-GFP fusion could be protected from proteolysis when co-expressed with the synthetic microcompartment operon. This work gives encouragement that it may be possible to harness the genes encoding a non-native microcompartment for future biotechnological applications.