Insight into the autoproteolysis mechanism of the RsgI9 anti-σ factor from Clostridium thermocellum.
Proteins
; 92(8): 946-958, 2024 Aug.
Article
de En
| MEDLINE
| ID: mdl-38597224
ABSTRACT
Clostridium thermocellum is a potential microbial platform to convert abundant plant biomass to biofuels and other renewable chemicals. It efficiently degrades lignocellulosic biomass using a surface displayed cellulosome, a megadalton sized multienzyme containing complex. The enzymatic composition and architecture of the cellulosome is controlled by several transmembrane biomass-sensing RsgI-type anti-σ factors. Recent studies suggest that these factors transduce signals from the cell surface via a conserved RsgI extracellular (CRE) domain (also called a periplasmic domain) that undergoes autoproteolysis through an incompletely understood mechanism. Here we report the structure of the autoproteolyzed CRE domain from the C. thermocellum RsgI9 anti-σ factor, revealing that the cleaved fragments forming this domain associate to form a stable α/ß/α sandwich fold. Based on AlphaFold2 modeling, molecular dynamics simulations, and tandem mass spectrometry, we propose that a conserved Asn-Pro bond in RsgI9 autoproteolyzes via a succinimide intermediate whose formation is promoted by a conserved hydrogen bond network holding the scissile peptide bond in a strained conformation. As other RsgI anti-σ factors share sequence homology to RsgI9, they likely autoproteolyze through a similar mechanism.
Mots clés
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Protéines bactériennes
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Clostridium thermocellum
/
Simulation de dynamique moléculaire
/
Protéolyse
Langue:
En
Journal:
Proteins
Sujet du journal:
BIOQUIMICA
Année:
2024
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique
Pays de publication:
États-Unis d'Amérique