An asymmetric nautilus-like HflK/C assembly controls FtsH proteolysis of membrane proteins.
bioRxiv
; 2024 Aug 10.
Article
em En
| MEDLINE
| ID: mdl-39149393
ABSTRACT
FtsH, a AAA protease, associates with HflK/C subunits to form a megadalton complex that spans the inner membrane and extends into the periplasm of E. coli . How this complex and homologous assemblies in eukaryotic organelles recruit, extract, and degrade membrane-embedded substrates is unclear. Following overproduction of protein components, recent cryo-EM structures reveal symmetric HflK/C cages surrounding FtsH in a manner proposed to inhibit degradation of membrane-embedded substrates. Here, we present structures of native complexes in which HflK/C instead forms an asymmetric nautilus-like assembly with an entryway for membrane-embedded substrates to reach and be engaged by FtsH. Consistent with this nautilus-like structure, proteomic assays suggest that HflK/C enhances FtsH degradation of certain membrane-embedded substrates. The membrane curvature in our FtsH·HflK/C complexes is opposite that of surrounding membrane regions, a property that correlates with lipid-scramblase activity and possibly with FtsH's function in the degradation of membrane-embedded proteins.
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Base de dados:
MEDLINE
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En
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BioRxiv
Ano de publicação:
2024
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Article