Probably forms vertices in the shell of the bacterial microcompartment (BMC) dedicated to 1,2-propanediol (1,2-PD) degradation. Required for structural integrity of BMCs and to mitigate propionaldehyde toxicity. The 1,2-PD-specific bacterial microcompartment (BMC) concentrates low levels of 1,2-PD catabolic enzymes, concentrates volatile reaction intermediates thus enhancing pathway flux and keeps the level of toxic, mutagenic propionaldehyde low. Polyol metabolism; 1,2-propanediol degradation. Homopentamer (By similarity). Interacts with shell protein PduA (By similarity). BMC production is induced by growth on 1,2-PD vitamin B12 medium. Forms BMCs with a variety of morphologies, including elongated, enlarged, and aggregated MCPs and some with rounded cross-sections. Grows in an interrupted manner on 1,2-PD and vitamin B12; grows for a while then stops, then restarts as if a toxic compound was accumulating and then decreases. Artificial BMCs can be made in E.coli by expressing pduA-pduB/B'-pduT-pduU-pduN-pduJ-pduK (in this order). Enzymes can be targeted to the BMC, and appear to be encapsulated within it. Bacterial microcompartments (BMC) 100-200 nm in cross section are formed during aerobic growth on minimal 1,2-PD-B12 or anaerobic growth on 1,2-PD-tetrathionate medium, but not during aerobic growth on glucose, anerobic growth on glucose or pyruvate-tetrathionate (PubMed:10498708). BMCs can constitute up to 10% of total cell protein (PubMed:12923081). Belongs to the CcmL/EutN family.