Protein Microcompartments Open New Possibilities in Biocatalytic Engineering

After observing protein compartments in certain bacteria that could isolate enzyme reactions, a team of University researchers worked to reproduce these reaction-containing microcompartments in a non-native host organism. Their goal was to create small bioreactors – nanobioreactors – within cells where specific enzyme actions could be targeted. The group, guided by BTI faculty member Claudia Schmidt-Dannert and post-doctoral researcher Swati Choudhary, recently succeeded in producing these protein microcompartments in non-native E. coli bacteria from the microcompartment shell proteins of the bacteria Salmonella enterica.

A bacterial microcompartment (BMC) is a polyhedral protein complex that acts as a kind of box or room within a cell where enzymes can react more efficiently. The BMC can contain enzymes involved in specific metabolic pathway reactions while also preventing toxic byproducts of the reactions from harming the host cell. BMCs were first observed by microscope in cyanobacteria in the 1950’s. Since then, it has become clear that these protein structures are produced by many types of bacteria for various functions.

“Bacterial microcompartment proteins have been identified in over 400 bacterial genomes,” explained Choudhary, “and they are associated with diverse metabolic pathways such as fixing CO2 and utilizing small organic compounds as sources of carbon and nitrogen.”

Interest in BMCs and their natural functions has grown in recent years. With more information on their properties now available, BMCs are becoming more practical for applications in synthetic biology.

The team of University researchers working to harness the potential of BMC’s as nanobioreactors was able to identify the proteins forming the outer shell and use these proteins to reproduce the compartments in non-native host bacteria. The results of the group’s project have potentially valuable applications beyond simply reproducing the microcompartment structure. Being able to create these reaction compartments in a variety of hosts will improve and streamline biocatalytic processes.

-Tim Montgomery