5CXK

Crystal structure of beta carbonic anhydrase from Vibrio cholerae

Summary for 5CXK

• Entry DOI: 10.2210/pdb5cxk/pdb
• Descriptor: Carbonic anhydrase, ZINC ION, BICARBONATE ION, ... (4 entities in total)
• Functional Keywords: lyase
• Biological source: Vibrio cholerae
• Total number of polymer chains: 8
• Total formula weight: 202478.14

Authors

Ferraroni, M.,Supuran, C. (deposition date: 2015-07-29, release date: 2015-12-09, Last modification date: 2024-01-10)

Primary citation

Ferraroni, M.,Del Prete, S.,Vullo, D.,Capasso, C.,Supuran, C.T.
Crystal structure and kinetic studies of a tetrameric type II beta-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae.
Acta Crystallogr.,Sect.D, 71:2449-2456, 2015

PubMed Abstract: Carbonic anhydrase (CA) is a zinc enzyme that catalyzes the reversible conversion of carbon dioxide to bicarbonate (hydrogen carbonate) and a proton. CAs have been extensively investigated owing to their involvement in numerous physiological and pathological processes. Currently, CA inhibitors are widely used as antiglaucoma, anticancer and anti-obesity drugs and for the treatment of neurological disorders. Recently, the potential use of CA inhibitors to fight infections caused by protozoa, fungi and bacteria has emerged as a new research direction. In this article, the cloning and kinetic characterization of the β-CA from Vibrio cholerae (VchCAβ) are reported. The X-ray crystal structure of this new enzyme was solved at 1.9 Å resolution from a crystal that was perfectly merohedrally twinned, revealing a tetrameric type II β-CA with a closed active site in which the zinc is tetrahedrally coordinated to Cys42, Asp44, His98 and Cys101. The substrate bicarbonate was found bound in a noncatalytic binding pocket close to the zinc ion, as reported for a few other β-CAs, such as those from Escherichia coli and Haemophilus influenzae. At pH 8.3, the enzyme showed a significant catalytic activity for the physiological reaction of the hydration of CO2 to bicarbonate and protons, with the following kinetic parameters: a kcat of 3.34 × 10(5) s(-1) and a kcat/Km of 4.1 × 10(7) M(-1) s(-1). The new enzyme, on the other hand, was poorly inhibited by acetazolamide (Ki of 4.5 µM). As this bacterial pathogen encodes at least three CAs, an α-CA, a β-CA and a γ-CA, these enzymes probably play an important role in the life cycle and pathogenicity of Vibrio, and it cannot be excluded that interference with their activity may be exploited therapeutically to obtain antibiotics with a different mechanism of action.

PubMed: 26627652
DOI: 10.1107/S1399004715018635

Experimental method

X-RAY DIFFRACTION (1.9 Å)