Team:Hong Kong HKU/background

From 2014.igem.org

Background

Background

Bacterial microcompartments (BMCs) - by its name, refers to large organelles that occur in prokaryotes to provide micro-compartmentalizations for various metabolical process. Lacking the feature of lipid membrane-bound organelles of eukaryotes, prokaryotes overcome the issue by constructing the compartment entirely of proteins, coded by just a few, small genes.

These gene products multimerize sequentially and exponentially, forming the compartment. The fact that these BMCs are coded by a few, simple genes makes them applicable to genetic engineering to various desired purposes.

Various BMCs that serve different metabolic purposes are well-characterized. Among the others, we chose a specific type termed the Eut BMC (Eut for Ethanolamine utilization) originated from Salmonella enterica. For a more detailed description of the BMCs, readers are recommended to refer to various expert reviews.

To structurally construct the compartments, 5 genes from the Eut gene cluster is required. They are: EutS, EutM, EutN, EutL, and EutK, the suffix alphabets being the designation of order of genes found in the Eut gene cluster.

The reason why Eut BMC was chosen is because (1) it is relatively unexplored, yet have an understanding deep enough for genetic engineering experiments; (2) a ready-to-use gene cluster was available from the iGEM Biobrick registry, backed by trustable literature characterization; (3) the "signal" peptide that targets enzymes to localize in the microcompartment is relatively simple compared to other BMCs.

Previous literatures have already described the N-terminal "signal" peptide that specifically targets proteins to localize into the BMCs, as well as isolating the BMC intact despite a relatively tedious and specialized method. To these we asked the questions from an engineering point of view: (1) can we isolate the compartment with a simpler method to make it more accessible by others? (2) can we construct a convenient genetic system that aids the BMC's expression, construction, cargo targeting, right to the end of its isolation? These two questions have both been answered and explored in our project with significant results.