1.S.1.1.2
EutM pore-forming shell protein of 96 aas with most of the protein except the C-terminus showing substantial hydrophobicity. It is in the ethanolamine metabolizing Eut microcompartment (Takenoya et al. 2010).  Compartmentalization prevents escape of volatile or toxic intermediates, prevents off-pathway reactions, and creates private cofactor pools. Encapsulation in synthetic microcompartment organelles enhances the function of heterologous pathways. To this end, Slininger Lee et al. 2017 explored how small differences in the shell protein structure result in changes in the diffusion of metabolites through the shell. The ethanolamine utilization (Eut) protein EutM properly incorporates into the 1,2-propanediol utilization (Pdu) microcompartment, altering native metabolite accumulation and the resulting growth on 1,2-propanediol as the sole carbon source. Further, we identified a single pore-lining residue mutation that confers the same phenotype as substitution of the full EutM protein, indicating that small molecule diffusion through the shell is the cause of growth enhancement. The hydropathy index and charge of pore amino acids are important indicators to predict how pore mutations affect growth on 1,2-propanediol, likely by controlling diffusion of one or more metabolites. This study highlights the use of two strategies to engineer microcompartments to control metabolite transport: altering the existing shell protein pore via mutation of the pore-lining residues, and generating chimeras using shell proteins with the desired pores (Slininger Lee et al. 2017). This is a BMC-H protein.