PT  - JOURNAL ARTICLE
AU  - Benedikt Junglas
AU  - Roberto Orru
AU  - Amelie Axt
AU  - Carmen Siebenaller
AU  - Wieland Steinchen
AU  - Jennifer Heidrich
AU  - Ute A. Hellmich
AU  - Nadja Hellmann
AU  - Eva Wolf
AU  - Stefan A. L. Weber
AU  - Dirk Schneider
TI  - IM30 IDPs form a membrane protective carpet upon super-complex disassembly
AID  - 10.1101/2020.09.16.299396
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.16.299396
4099  - http://biorxiv.org/content/early/2020/09/16/2020.09.16.299396.short
4100  - http://biorxiv.org/content/early/2020/09/16/2020.09.16.299396.full
AB  - Members of the phage shock protein A (PspA) family, including the inner membrane-associated protein of 30 kDa (IM30), are suggested to stabilize stressed cellular membranes. Furthermore, IM30 is essential in thylakoid membrane-containing chloroplasts and cyanobacteria, where it is involved in membrane biogenesis and/or remodeling. While it is well known that PspA and IM30 bind to membranes, the mechanism of membrane stabilization is still enigmatic. Here we report that ring-shaped IM30 super-complexes disassemble on membranes, resulting in formation of a membrane-protecting protein carpet. Upon ring dissociation, the C-terminal domain of IM30 unfolds, and the protomers self-assemble on membranes. IM30 assemblies at membranes have been observed before in vivo and were associated to stress response in cyanobacteria and chloroplasts. These assemblies likely correspond to the here identified carpet structures. Our study defines the thus far enigmatic structural basis for the physiological function of IM30 and related proteins, including PspA, and highlights a hitherto unrecognized concept of membrane stabilization by intrinsically disordered proteins.Competing Interest StatementThe authors have declared no competing interest.