Int. J. Mol. Sci. 2012, 13(7), 8038-8050; doi:10.3390/ijms13078038
Review

From Evolution to Pathogenesis: The Link Between β-Barrel Assembly Machineries in the Outer Membrane of Mitochondria and Gram-Negative Bacteria

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Received: 1 May 2012; in revised form: 21 June 2012 / Accepted: 21 June 2012 / Published: 28 June 2012
(This article belongs to the Special Issue Membrane Transport)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: β-barrel proteins are the highly abundant in the outer membranes of Gram-negative bacteria and the mitochondria in eukaryotes. The assembly of β-barrels is mediated by two evolutionary conserved machineries; the β-barrel Assembly Machinery (BAM) in Gram-negative bacteria; and the Sorting and Assembly Machinery (SAM) in mitochondria. Although the BAM and SAM have functionally conserved roles in the membrane integration and folding of β-barrel proteins, apart from the central BamA and Sam50 proteins, the remaining components of each of the complexes have diverged remarkably. For example all of the accessory components of the BAM complex characterized to date are located in the bacterial periplasm, on the same side as the N-terminal domain of BamA. This is the same side of the membrane as the substrates that are delivered to the BAM. On the other hand, all of the accessory components of the SAM complex are located on the cytosolic side of the membrane, the opposite side of the membrane to the N-terminus of Sam50 and the substrate receiving side of the membrane. Despite the accessory subunits being located on opposite sides of the membrane in each system, it is clear that each system is functionally equivalent with bacterial proteins having the ability to use the eukaryotic SAM and vice versa. In this review, we summarize the similarities and differences between the BAM and SAM complexes, highlighting the possible selecting pressures on bacteria and eukaryotes during evolution. It is also now emerging that bacterial pathogens utilize the SAM to target toxins and effector proteins to host mitochondria and this will also be discussed from an evolutionary perspective.
Keywords: β-barrel proteins; mitochondria; bacteria; outer membrane; protein transport; protein folding; evolution
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MDPI and ACS Style

Jiang, J.-H.; Tong, J.; Tan, K.S.; Gabriel, K. From Evolution to Pathogenesis: The Link Between β-Barrel Assembly Machineries in the Outer Membrane of Mitochondria and Gram-Negative Bacteria. Int. J. Mol. Sci. 2012, 13, 8038-8050.

AMA Style

Jiang J-H, Tong J, Tan KS, Gabriel K. From Evolution to Pathogenesis: The Link Between β-Barrel Assembly Machineries in the Outer Membrane of Mitochondria and Gram-Negative Bacteria. International Journal of Molecular Sciences. 2012; 13(7):8038-8050.

Chicago/Turabian Style

Jiang, Jhih-Hang; Tong, Janette; Tan, Kher Shing; Gabriel, Kipros. 2012. "From Evolution to Pathogenesis: The Link Between β-Barrel Assembly Machineries in the Outer Membrane of Mitochondria and Gram-Negative Bacteria." Int. J. Mol. Sci. 13, no. 7: 8038-8050.


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