8T9N

Bacillus subtilis RsgI GGG mutant

Summary for 8T9N

• Entry DOI: 10.2210/pdb8t9n/pdb
• Descriptor: Anti-sigma-I factor RsgI (2 entities in total)
• Functional Keywords: autoproteolysis, sea domain, mechanotransduction, regulated intramembrane proteolysis (rip), adhesion gpcr, cellulosomes, sigi/rsgi, membrane protein
• Biological source: Bacillus subtilis
• Total number of polymer chains: 2
• Total formula weight: 30836.33

Authors

Brogan, A.P.,Habib, C.,Hobbs, S.J.,Kranzusch, P.J.,Rudner, D.Z. (deposition date: 2023-06-24, release date: 2023-09-20, Last modification date: 2023-10-25)

Primary citation

Brogan, A.P.,Habib, C.,Hobbs, S.J.,Kranzusch, P.J.,Rudner, D.Z.
Bacterial SEAL domains undergo autoproteolysis and function in regulated intramembrane proteolysis.
Proc.Natl.Acad.Sci.USA, 120:e2310862120-e2310862120, 2023

PubMed Abstract: Gram-positive bacteria use SigI/RsgI-family sigma factor/anti-sigma factor pairs to sense and respond to cell wall defects and plant polysaccharides. In this signal transduction pathway involves regulated intramembrane proteolysis (RIP) of the membrane-anchored anti-sigma factor RsgI. However, unlike most RIP signaling pathways, site-1 cleavage of RsgI on the extracytoplasmic side of the membrane is constitutive and the cleavage products remain stably associated, preventing intramembrane proteolysis. The regulated step in this pathway is their dissociation, which is hypothesized to involve mechanical force. Release of the ectodomain enables intramembrane cleavage by the RasP site-2 protease and activation of SigI. The constitutive site-1 protease has not been identified for any RsgI homolog. Here, we report that RsgI's extracytoplasmic domain has structural and functional similarities to eukaryotic SEA domains that undergo autoproteolysis and have been implicated in mechanotransduction. We show that site-1 proteolysis in and Clostridial RsgI family members is mediated by enzyme-independent autoproteolysis of these SEA-like domains. Importantly, the site of proteolysis enables retention of the ectodomain through an undisrupted β-sheet that spans the two cleavage products. Autoproteolysis can be abrogated by relief of conformational strain in the scissile loop, in a mechanism analogous to eukaryotic SEA domains. Collectively, our data support the model that RsgI-SigI signaling is mediated by mechanotransduction in a manner that has striking parallels with eukaryotic mechanotransducive signaling pathways.

PubMed: 37756332
DOI: 10.1073/pnas.2310862120

Experimental method

X-RAY DIFFRACTION (1.9 Å)