Probably a major component of the bacterial microcompartment (BMC) shell dedicated to ethanolamine degradation (PubMed:22428024, PubMed:27063436). Each homohexamer has a central pore with an opening of up to 8.6 Angstroms. A positively-charged funnel leads to the pore from each side of the hexamer. The pore probably allows metabolite passage into and out of the BMC (By similarity). Expression of eutK, eutL, eutM, eutN, eutS (eutSMNLK) in E.coli leads to formation of a single BMC. Expression alone leads to thick filaments that interfere with cell separation (PubMed:22428024, PubMed:27063436). Coexpression of eutQ with eutSMNLK permits E.coli to make cells with more than one mobile BMC, as is usual in vivo. May play a role in BMC shell biogenesis (PubMed:27063436). Can replace homolog pduA in the pdu operon, cells grow better than wild-type on 1,2-propanediol and vitamin B12. Protein is incorporated into the pdu BMC microcompartment (PubMed:28585808). 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 (Probable) (PubMed:16585748). Deletion of BMC genes (eutK, eutL, eutM) restores growth of eutD deletions, suggesting there are dedicated pools of coenzyme A (CoA) and NAD in the BMC (PubMed:23585538). 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 of up to 8.6 Angstroms diameter. The hexamers pack into a two-dimensional array (By similarity). Interacts with EutQ; a probably cytoplasm-facing helix (Val-49 to Gln-64) interacts with N-terminus of EutQ (PubMed:27063436). Part of the 17-gene eut operon transcribed from a single promoter, induced by ethanolamine and adenosylcobalamin (AdoCbl, vitamin B12). Essential, it cannot be deleted when the 17-gene operon is otherwise intact, possibly due to polar effects on downstream genes (PubMed:7868611). Not required for cobalamin-dependent degradation of ethanolamine (EA) when polar effects are removed. A double eutD-eutM deletion is also not required for growth in the above conditions (PubMed:10464203). A double eutM-eutN strain grows as well as wild-type on EA and cyanocobalamin, but a quadruple eutL-eutK eutM-eutN strain does not grow (PubMed:16291677). A non-polar deletion mutant grows on EA at pH 5.5 to pH 7.0 but not at pH 8.0 or pH 8.5, releases increased amounts of acetaldehyde on EA plus vitamin B12. Preventing acetaldehyde vapor loss allows growth up to pH 8.5 (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 them and 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). Can incorporate into the pdu BMC where it alters growth, suggesting fine-tuning metabolite flux by using different BMC components is possible (PubMed:28585808). Can be used as a self-assembling protein scaffold for synthetic biology. Overexpressed, purified protein with a SpyCatcher tag added to the C-terminus yields self-assembling fibrils that are stable at pH 5-9 and up to 50 degrees Celsius. Addition of SpyTagged cargo proteins leads to isopeptide bond formation between the scaffold and cargo proteins, colocalizing and stabilizing the cargo proteins and reducing the time for the reaction to make maximimal product. 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 bacterial microcompartments protein family.