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Volume 32, No 2, Feb 2022
ISSN: 1001-0602
EISSN: 1748-7838 2018
impact factor 17.848*
(Clarivate Analytics, 2019)
Volume 32 Issue 2, February 2022: 176-189
Structural insights into the membrane microdomain organization by SPFH family proteins
Chengying Ma1,† , Chengkun Wang1,† , Dingyi Luo1 , Lu Yan1 , Wenxian Yang1 , Ningning Li1 , Ning Gao1,2,*
1State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Centre for Life Sciences, School of Life Sciences, Peking University, Beijing, ChinaThe lateral segregation of membrane constituents into functional microdomains, conceptually known as lipid raft, is a universal organization principle for cellular membranes in both prokaryotes and eukaryotes. The widespread Stomatin, Prohibitin, Flotillin, and HflK/C (SPFH) family proteins are enriched in functional membrane microdomains at various subcellular locations, and therefore were hypothesized to play a scaffolding role in microdomain formation. In addition, many SPFH proteins are also implicated in highly specific processes occurring on the membrane. However, none of these functions is understood at the molecular level. Here we report the structure of a supramolecular complex that is isolated from bacterial membrane microdomains and contains two SPFH proteins (HflK and HflC) and a membrane-anchored AAA+ protease FtsH. HflK and HflC form a circular 24-mer assembly, featuring a laterally segregated membrane microdomain (20 nm in diameter) bordered by transmembrane domains of HflK/C and a completely sealed periplasmic vault. Four FtsH hexamers are embedded inside this microdomain through interactions with the inner surface of the vault. These observations provide a mechanistic explanation for the role of HflK/C and their mitochondrial homologs prohibitins in regulating membrane-bound AAA+ proteases, and suggest a general model for the organization and functionalization of membrane microdomains by SPFH proteins.
https://doi.org/10.1038/s41422-021-00598-3
