| Description | Members of this group are bacterial microcompartment shell proteins: PduT of Salmonella enterica and its orthologs in the propriondiol and ethanolamine operons of bacteria [ , , , ].Some non-autotrophic organisms form polyhedral organelles, enterosomes [ ], that resemble the carboxysomes found in autotrophs, particularly the cyanobacteria. Carboxysomes are well-studied polyhedral organelles found in cyanobacteria and some chemoautotrophs [, ]. They are composed of a proteinaceous shell that houses most of the cell s ribulose bisphosphate carboxylase/oxygenase (RuBisCO). They are required for autotrophic growth at low CO2concentrations and are thought to function as part of a CO 2-concentrating mechanism [ , ].Polyhedral organelles, enterosomes, from non-autotrophic organisms are involved in coenzyme B12-dependent 1,2-propanediol utilization (e.g., in S. enterica, [ ]) and ethanolamine utilization (e.g., in Salmonella typhimurium []). Genes needed for enterosome formation are located in the 1,2-propanediol utilization pdu[ , ] or ethanolamine utilization eut[ , ] operons, respectively. Although enterosomes of non-autotrophic organisms are apparently related to carboxysomes structurally, a functional relationship is uncertain. A role in CO2concentration, similar to that of the carboxysome, is unlikely since there is no known association between CO 2and coenzyme B12-dependent 1,2-propanediol or ethanolamine utilization [ ].In S. enterica the propriondiol degrading enterosome consists of at least 15 proteins, of which, at least, seven are shell proteins: pduA [ ], pduB, B', J, K, T and U. In addition the organelle contains four enzymes: B12-dependent diol dehydratase (pduCDE) and its reactivating factor (pduGH), CoA-dependent proprionaldehyde dehydrogenase (pduP, [ ]) and adenosyl transferase (pduO) []. It has been suggested that enterosomes sequester toxic aldehydes formed during both 1,2-propanediol and ethanolamine degradation and channel them to subsequent pathway enzymes. It has also been suggested that polyhedra might be used to protect diol dehydratase and ethanolamine ammonia-lyase from oxygen, to which both are sensitive [, ]. Mutational studies of PduA indicate that the organelles of S. enterica are not involved in concentrating 1,2-propanediol or CN-B12, but are consistent with a role in moderating aldehyde toxicity [, ]. | Name | Bacterial microcompartment shell protein PduT |
| Short Name | Micro_shell_prot_PduT | Type | Family |
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