Radical transfer but not heme distal residues is essential for pH dependence of dye-decolorizing activity of peroxidase from Vibrio cholerae

• Published in: Journal of inorganic biochemistry 2021-06, Vol.219, p.111422-111422, Article 111422
• Main Authors: Uchida, Takeshi, Omura, Issei, Umetsu, Sayaka, Ishimori, Koichiro
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Amino Acids - metabolism; Anthraquinones - chemistry; Anthraquinones - metabolism; Binding Sites; Catalysis; Catalytic Domain; Coloring Agents - chemistry; Coloring Agents - metabolism; Crystallography, X-Ray - methods; Dye-degradation; Enzyme; Heme; Heme - chemistry; Heme - metabolism; Histidine - chemistry; Histidine - metabolism; Hydrogen Bonding; Hydrogen-Ion Concentration; Mutation; Peroxidase; Peroxidase - chemistry; Peroxidase - genetics; Peroxidase - metabolism; Reaction mechanism; Vibrio cholerae; Vibrio cholerae - enzymology
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/j.jinorgbio.2021.111422

Dye-decolorizing peroxidase (DyP) is a heme-containing enzyme that catalyzes the degradation of anthraquinone dyes. A main feature of DyP is the acidic optimal pH for dye-decolorizing activity. In this study, we constructed several mutant DyP enzymes from Vibrio cholerae (VcDyP), with a view to identifying the decisive factor of the low pH preference of DyP. Initially, distal Asp144, a conserved residue, was replaced with His, which led to significant loss of dye-decolorizing activity. Introduction of His into a position slightly distant from heme resulted in restoration of activity but no shift in optimal pH, indicating that distal residues do not contribute to the pH dependence of catalytic activity. His178, an essential residue for dye decolorization, is located near heme and forms hydrogen bonds with Asp138 and Thr278. While Trp and Tyr mutants of His178 were inactive, the Phe mutant displayed ~35% activity of wild-type VcDyP, indicating that this position is a potential radical transfer route from heme to the active site on the protein surface. The Thr278Val mutant displayed similar enzymatic properties as WT VcDyP, whereas the Asp138Val mutant displayed significantly increased activity at pH 6.5. On the basis of these findings, we propose that neither distal amino acid residues, including Asp144, nor hydrogen bonds between His178 and Thr278 are responsible while the hydrogen bond between His178 and Asp138 plays a key role in the pH dependence of activity. Dye-decolorizing peroxidase (DyP) catalyzes degradation of anthraquinone dyes. A main feature of DyP is the acidic optimum pH for dye-decolorizing activity. We found that distal amino acid residues including Asp144 are not, but the hydrogen bond between Asp138 and His178 plays key role in the pH dependence of dye-decolorizing activity. [Display omitted] •Histidine instead of a conserved aspartic acid can act as an acid-base catalyst.•Distal amino acid residues do not contribute to pH dependence of the activity.•VcDyP is the Dye-decolorizing peroxidase from Vibrio cholera.•Asp138 located near heme is a possible determinant of pH dependent activity of VcDyP.