9JYW

Crystal structure of the gamma-carbonic anhydrase from the polyextremophilic bacterium Aeribacillus pallidus

Summary for 9JYW

• Entry DOI: 10.2210/pdb9jyw/pdb
• Descriptor: Gamma carbonic anhydrase family protein, ZINC ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: gamma-class carbonic anhydrase, zinc metalloenzyme, aeribacillus pallidus, carbon dioxide hydration, metal binding protein
• Biological source: Aeribacillus pallidus
• Total number of polymer chains: 6
• Total formula weight: 117144.85

Authors

Choi, S.H.,Jin, M.S. (deposition date: 2024-10-13, release date: 2024-12-11, Last modification date: 2025-01-01)

Primary citation

Choi, S.H.,Jin, M.S.
Crystal structure of gamma-carbonic anhydrase from the polyextremophilic bacterium Aeribacillus pallidus.
Mol.Cells, 48:100165-100165, 2024

PubMed Abstract: The polyextremophilic bacterium Aeribacillus pallidus produces a thermo- and alkali-stable γ-carbonic anhydrase (γ-apCA), a homotrimeric metalloenzyme containing a zinc ion in its active site that catalyzes the reversible hydration of carbon dioxide (CO). Here, we present the first crystal structure of γ-apCA at 1.7-Å resolution, revealing 2 trimers in the asymmetric unit. The overall structure is consistent with other γ-CAs, where each monomer adopts a prism-like structure consisting of an N-terminal left-handed β-helix and a C-terminal α-helix. The active site, located at the interface between 2 monomers, coordinates the zinc ion with 3 histidine residues (H65, H82, and H87) and a water molecule in a tetrahedral configuration. The structural comparison indicates that the amino acid composition at the active site of γ-apCA differs significantly from the prototypic γ-CA from Methanosarcina thermophila. This variation likely accounts for the lack of measurable CO hydration activity in γ-apCA. Additionally, the structure reveals noncatalytic zinc and sulfate ions trapped at the trimer core and trimer-trimer noncrystallographic interfaces. These may contribute to stabilizing enzyme assembly and promoting crystal packing.

PubMed: 39637945
DOI: 10.1016/j.mocell.2024.100165

Experimental method

X-RAY DIFFRACTION (1.7 Å)