7VN0

CATPO mutant - T188A

Summary for 7VN0

• Entry DOI: 10.2210/pdb7vn0/pdb
• Descriptor: Catalase, CIS-HEME D HYDROXYCHLORIN GAMMA-SPIROLACTONE, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: catalase, phenol oxidase, lateral channel, mutant, oxidoreductase
• Biological source: Mycothermus thermophilus
• Total number of polymer chains: 4
• Total formula weight: 320507.83

Authors

Yuzugullu Karakus, Y.,Balci Unver, S.,Zengin Karatas, M.,Goc, G.,Pearson, A.R.,Yorke, B. (deposition date: 2021-10-10, release date: 2022-09-14, Last modification date: 2024-02-14)

Primary citation

Yuzugullu Karakus, Y.,Goc, G.,Zengin Karatas, M.,Balci Unver, S.,Yorke, B.A.,Pearson, A.R.
Investigation of how gate residues in the main channel affect the catalytic activity of Scytalidium thermophilum catalase.
Acta Crystallogr D Struct Biol, 80:101-112, 2024

PubMed Abstract: Catalase is an antioxidant enzyme that breaks down hydrogen peroxide (HO) into molecular oxygen and water. In all monofunctional catalases the pathway that HO takes to the catalytic centre is via the `main channel'. However, the structure of this channel differs in large-subunit and small-subunit catalases. In large-subunit catalases the channel is 15 Å longer and consists of two distinct parts, including a hydrophobic lower region near the heme and a hydrophilic upper region where multiple HO routes are possible. Conserved glutamic acid and threonine residues are located near the intersection of these two regions. Mutations of these two residues in the Scytalidium thermophilum catalase had no significant effect on catalase activity. However, the secondary phenol oxidase activity was markedly altered, with k and k/K values that were significantly increased in the five variants E484A, E484I, T188D, T188I and T188F. These variants also showed a lower affinity for inhibitors of oxidase activity than the wild-type enzyme and a higher affinity for phenolic substrates. Oxidation of heme b to heme d did not occur in most of the studied variants. Structural changes in solvent-chain integrity and channel architecture were also observed. In summary, modification of the main-channel gate glutamic acid and threonine residues has a greater influence on the secondary activity of the catalase enzyme, and the oxidation of heme b to heme d is predominantly inhibited by their conversion to aliphatic and aromatic residues.

PubMed: 38265876
DOI: 10.1107/S2059798323011063

Experimental method

X-RAY DIFFRACTION (1.4 Å)