A probably major component of the bacterial microcompartment (BMC) shell dedicated to ethanolamine degradation. Expression of eutK, eutL, eutM, eutN, eutS (eutSMNLK) in E.coli leads to formation of a single BMC; expression of this protein alone can also form BMCs (which may be less tightly closed than eutSMNLK shells). The 'bent' shape of this subunit is required for integration of cargo proteins into these BMCs (PubMed:22428024). Coexpression of eutQ with eutSMNLK permits E.coli to make cells with more than one mobile BMC, as is usual in vivo (PubMed:27063436). Targets at least 2 proteins (EutC and EutE) to the interior of the BMC (PubMed:22428024, PubMed:27063436, PubMed:27450681). Proteins such as EutS containing circularly permuted BMC domains may play a key role in conferring heterogeneity and flexibility in this BMC (Probable). The ethanolamine (EA) catabolic bacterial microcompartment (BMC) probably concentrates low levels of ethanolamine catabolic enzymes, concentrates volatile reaction intermediates, keeps the level of toxic acetaldehyde low, generates enough acetyl-CoA to support cell growth, and maintains a pool of free coenzyme A (CoA) and NAD. Expression of the eut operon allows this bacteria to use ethanolamine as a carbon, nitrogen and energy source. It relies on cobalamin (vitamin B12) both as a cofactor for the ethanolamine ammonia-lyase (EAL) activity and to induce the operon (PubMed:3045078). EA enhances bacterial survival in macrophages in a concentration-dependent manner, suggesting it is an important nutrient during infection (PubMed:29531136). Amine and polyamine degradation; ethanolamine degradation. Homohexamer with a central pore; the hexamer is probably bent by about 40 degrees rather that symmetric; bending depends on Gly-39 (Probable). Interacts with the N-terminus of EutC, targeting it to the interior of the BMC (PubMed:22428024, PubMed:27063436, PubMed:27450681). Interacts with the N-terminus of EutE, targeting it to the interior of the BMC (PubMed:27450681). The first gene of the 17-gene eut operon transcribed from a single promoter, induced by ethanolamine and adenosylcobalamin (AdoCbl, vitamin B12) (PubMed:3045078). Expressed at low levels following mouse infection, not induced in infected macrophages or in spleen (PubMed:26565973). Adding an N- or C-terminal His-tag to this protein prevents it forming BMCs (PubMed:27450681). One side of the hexamer is concave and lined by hydrophobic residues, the other side has a slightly protruding, 6-stranded beta-barrel (By similarity). Not required for aerobic growth on ethanolamine (EA) supplemented with cobalamin (vitamin B12) (PubMed:10464203, PubMed:16291677). A non-polar deletion mutant grows on EA from pH 5.5 to pH 8.0, but does not grow at pH 8.5, releases increased amounts of acetaldehyde on EA plus vitamin B12 (PubMed:16585748). Artificial BMCs can be made in E.coli by expressing eutK, eutL, eutM, eutN, eutS (eutSMNLK) or eutS alone. Cargo proteins can be targeted to both BMCs; beta-galactosidase (lacZ) was active within the BMC, showing the BMC allows passage of substrate into the interior. This can lead to the development of tailored BMCs for specific metabolic reactions (PubMed:22428024, PubMed:27063436). The addition of eutQ to the eutSMNLK construct results in biogenesis of multiple BMCs (PubMed:27063436). The need for a bacterial microcompartment in EA metabolism can be bypassed by increasing the levels of EAL and an acetaldehyde dehydrogenase (not necessarily EutE). Belongs to the EutS/PduU family.