Plays an essential role in assembly and/or stability of the bacterial microcompartment (BMC) dedicated to 1,2-propanediol (1,2-PD) degradation. Expression of a cosmid containing the full 21-gene pdu operon in E.coli allows E.coli to grow on 1,2-propanediol (1,2-PD) with the appearance of bacterial microcompartments (BMC) in its cytoplasm. 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. Interacts with shell protein PduK. Belongs to the PduM family.