Family

Polyhedral organelle shell protein, EutL/PduB type (IPR009193)

Short name: EutL_PduB

Overlapping homologous superfamilies

None.

Family relationships

Description

Members of this family are polyhedral organelle shell proteins from non-autotrophic organisms. Other polyhedral organelle proteins are in IPR011238, IPR009307 and IPR004992. This family is distantly related to IPR011238, and IPR009307.

Some non-autotrophic organisms form polyhedral organelles resembling carboxysomes found in autotrophs. Carboxysomes are well-studied polyhedral organelles found in cyanobacteria and some chemoautotrophs [PMID: 9891798, PMID: 7934888]. 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 CO2 concentrations and are thought to function as part of a CO2-concentrating mechanism.

Polyhedral organelles in non-autotrophic organisms are involved in coenzyme B12-dependent 1,2-propanediol utilization (e.g., in Salmonella enterica) and ethanolamine utilization (e.g., in Salmonella typhimurium) [PMID: 10498708, PMID: 7868611]. Genes needed for polyhedral organelle formation are located at the 1,2-propanediol utilization pdu [PMID: 11844753, PMID: 10498708] or ethanolamine utilization eut [PMID: 7868611, PMID: 10464203] operons, respectively. Although polyhedral bodies of non-autotrophic organisms are apparently related to carboxysomes structurally, a functional relationship is uncertain. A role in CO2 concentration, similar to that of the carboxysome, is unlikely since there is no known association between CO2 and coenzyme B12-dependent 1,2-propanediol or ethanolamine utilization [PMID: 11844753]. These organelles are believed to consist of a proteinaceous shell that encases coenzyme B12-dependent diol dehydratase (which was found to be associated with them) [PMID: 10498708] or ethanolamine ammonia-lyase. It was suggested that polyhedral bodies could be used to sequester toxic aldehydes formed both during 1,2-propanediol and ethanolamine degradation and channel them to subsequent pathway enzymes. It was also suggested that polyhedra might be used to protect diol dehydratase and ethanolamine ammonia-lyase from oxygen to which both are sensitive [PMID: 10498708]. 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 [PMID: 11844753].

Members of this family include Escherichia coli and Salmonella EutL, involved in ethanolamine utilization [PMID: 10464203], as well as S. enterica PduB, involved in propanediol utilization [PMID: 10498708].

GO terms

Biological Process

GO:0009605 response to external stimulus

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PIRSF