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Biophys J. 2018 Nov 6;115(9):1755-1761. doi: 10.1016/j.bpj.2018.09.024. Epub 2018 Oct 2.

Single-Molecule Analyses Reveal Rhomboid Proteins Are Strict and Functional Monomers in the Membrane.

Author information

1
Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland.
2
Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland. Electronic address: surban@jhmi.edu.

Abstract

Intramembrane proteases hydrolyze peptide bonds within the membrane as a regulatory paradigm that is conserved across all forms of cellular life. Many of these enzymes are thought to be oligomeric, and that their resulting quaternary interactions form the basis of their regulation. However, technical limitations have precluded directly determining the oligomeric state of intramembrane proteases in any membrane. Using single-molecule photobleaching, we determined the quaternary structure of 10 different rhomboid proteins (the largest superfamily of intramembrane proteases) and six unrelated control proteins in parallel detergent micelle, planar supported lipid bilayer, and whole-cell systems. Bacterial, parasitic, insect, and human rhomboid proteases and inactive rhomboid pseudoproteases all proved to be monomeric in all membrane conditions but dimeric in detergent micelles. These analyses establish that rhomboid proteins are, as a strict family rule, structurally and functionally monomeric by nature and that rhomboid dimers are unphysiological.

PMID:
30342748
PMCID:
PMC6224778
[Available on 2019-11-06]
DOI:
10.1016/j.bpj.2018.09.024

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