Selective molecular transport across the protein shells of bacterial microcompartments

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Highlights

  • A key feature of bacterial microcompartments is a selectively permeable protein shell.

  • The shells of microcompartments are able to retain toxic or volatile metabolites while allowing substrates, products and cofactors to pass.

  • The central pores in microcompartment shell proteins control shell permeability based on their size, and their electrostatic and dynamic properties.

  • Molecular transport across microcompartment shells appears to be regulated at multiple levels, but the details are obscure.

Bacterial microcompartments are widespread organelles that play important roles in the environment and are associated with a number of human diseases. A key feature of bacterial MCPs is a selectively permeable protein shell that mediates the movement of substrates, products and cofactors in and out. Here we discuss current knowledge of selective transport across the protein shells of bacterial MCPs, including mechanisms, regulation and unanswered questions.

Section snippets

Unanswered questions about molecular transport across MCP shells

There are a number of puzzling questions surrounding molecular transport across MCP shells. As mentioned above, there is compelling evidence that the shell of the Pdu MCP restricts the outward diffusion of propionaldehyde. However, at the same time, the substrates and products of the Pdu MCP (1,2-propanediol, propionyl-phosphate and 1-propanol) must be efficiently transported across the shell and the lumen enzymes must be supplied with required cofactors: NAD+, NADH, FAD, ATP, HS-CoA and

Conflict of interest statement

Nothing declared.

Acknowledgement

This work was supported by grant AI081146 from the National Institutes of Health to T.A.B.

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