Structural insights into novel mechanisms of inhibition of the major β-carbonic anhydrase CafB from the pathogenic fungus Aspergillus fumigatus
| Autor: | Subin Kim, Mi Sun Jin, Jongmin Sung, Jungyoon Yeon, Na Jin Kim, Semi Hong |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Mutant
chemistry.chemical_element Zinc Crystallography X-Ray Catalysis Aspergillus fumigatus Enzyme catalysis 03 medical and health sciences Structural Biology Carbonic anhydrase Catalytic Domain 030304 developmental biology Carbonic Anhydrases chemistry.chemical_classification 0303 health sciences biology Chemistry 030302 biochemistry & molecular biology Active site biology.organism_classification Kinetics Enzyme Biochemistry biology.protein Cysteine |
| Zdroj: | Journal of structural biology. 213(1) |
| ISSN: | 1095-8657 |
| Popis: | In fungi the β-class of carbonic anhydrases (β-CAs) are zinc metalloenzymes that are essential for growth, survival, differentiation, and virulence. Aspergillus fumigatus is the most important pathogen responsible for invasive aspergillosis and possesses two major β-CAs, CafA and CafB. Recently we reported the biochemical characterization and 1.8 A crystal structure of CafA. Here, we report a crystallographic analysis of CafB revealing the mechanism of enzyme catalysis and establish the relationship of this enzyme to other β-CAs. While CafA has a typical open conformation, CafB, when exposed to acidic pH and/or an oxidative environment, has a novel type of active site in which a disulfide bond is formed between two zinc-ligating cysteines, expelling the zinc ion and stabilizing the inactive form of the enzyme. Based on the structural data, we generated an oxidation-resistant mutant (Y159A) of CafB. The crystal structure of the mutant under reducing conditions retains a catalytic zinc at the expected position, tetrahedrally coordinated by three residues (C57, H113 and C116) and an aspartic acid (D59), and replacing the zinc-bound water molecule in the closed form. Furthermore, the active site of CafB crystals grown under zinc-limiting conditions has a novel conformation in which the solvent-exposed catalytic cysteine (C116) is flipped out of the metal coordination sphere, facilitating release of the zinc ion. Taken together, our results suggest that A. fumigatus use sophisticated activity-inhibiting strategies to enhance its survival during infection. |
| Databáze: | OpenAIRE |
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