7SJY

Crystal structure of Clostridium thermocellum RsgI9 S1C-NTF2 bi-domain

Summary for 7SJY

• Entry DOI: 10.2210/pdb7sjy/pdb
• Descriptor: Anti-sigma-I factor RsgI9, GLYCEROL (3 entities in total)
• Functional Keywords: anti-sigma factor, s1c peptidase, ntf2-like, hydrolase
• Biological source: Acetivibrio thermocellus DSM 1313 (Clostridium thermocellum)
• Total number of polymer chains: 2
• Total formula weight: 70371.80

Authors

Mahoney, B.J.,Cascio, D.,Clubb, R.T. (deposition date: 2021-10-19, release date: 2022-03-02, Last modification date: 2023-10-18)

Primary citation

Mahoney, B.J.,Takayesu, A.,Zhou, A.,Cascio, D.,Clubb, R.T.
The structure of the Clostridium thermocellum RsgI9 ectodomain provides insight into the mechanism of biomass sensing.
Proteins, 90:1457-1467, 2022

PubMed Abstract: Clostridium thermocellum is actively being developed as a microbial platform to produce biofuels and chemicals from renewable plant biomass. An attractive feature of this bacterium is its ability to efficiently degrade lignocellulose using surface-displayed cellulosomes, large multi-protein complexes that house different types of cellulase enzymes. Clostridium thermocellum tailors the enzyme composition of its cellulosome using nine membrane-embedded anti-σ factors (RsgI1-9), which are thought to sense different types of extracellular carbohydrates and then elicit distinct gene expression programs via cytoplasmic σ factors. Here we show that the RsgI9 anti-σ factor interacts with cellulose via a C-terminal bi-domain unit. A 2.0 Å crystal structure reveals that the unit is constructed from S1C peptidase and NTF2-like protein domains that contain a potential binding site for cellulose. Small-angle X-ray scattering experiments of the intact ectodomain indicate that it adopts a bi-lobed, elongated conformation. In the structure, a conserved RsgI extracellular (CRE) domain is connected to the bi-domain via a proline-rich linker, which is expected to project the carbohydrate-binding unit ~160 Å from the cell surface. The CRE and proline-rich elements are conserved in several other C. thermocellum anti-σ factors, suggesting that they will also form extended structures that sense carbohydrates.

PubMed: 35194841
DOI: 10.1002/prot.26326

Experimental method

X-RAY DIFFRACTION (2 Å)