A component of the bacterial microcompartment (BMC) shell dedicated to ethanolamine degradation. Its unusual hexameric shape may help form the BMC shell (Probable). Targets at least 2 proteins (EutC and EutE) to the interior of the BMC (By similarity). Proteins such as EutS containing circularly permuted BMC domains may play a key role in conferring heterogeneity and flexibility in this BMC (Probable). Amine and polyamine degradation; ethanolamine degradation. Homohexamer with a central pore; the hexamer is not symmetric, it is bent by about 40 degrees; bending depends on Gly-39 (PubMed:20044574). Interacts with the N-terminus of EutC and of EutE, targeting them to the interior of the BMC (By similarity). One side of the hexamer is concave and lined by hydrophobic residues, the other side has a slightly protruding, 6-stranded beta-barrel. Belongs to the EutS/PduU family. In strain MG1655 the eut operon is interrupted by the CPZ-55 prophage, encoding 9 genes situated between eutA and eutB, which are translated in the other direction. CPZ-55 may prevent expression of the eut operon in strain MG1655. Strain W3110 does not have this prophage element and should be able to express the operon.