9D0Z
X-ray crystal structure of H157Q variant Thermothelomyces thermophilus polysaccharide monooxygenase 9E
Summary for 9D0Z
| Entry DOI | 10.2210/pdb9d0z/pdb |
| Descriptor | Glycoside hydrolase family 61 protein, COPPER (II) ION, OXYGEN MOLECULE, ... (5 entities in total) |
| Functional Keywords | polysaccharide monooxygenase, oxidoreductase |
| Biological source | Thermothelomyces thermophilus |
| Total number of polymer chains | 2 |
| Total formula weight | 49014.99 |
| Authors | Thomas, W.C.,Batka, A.E.,Marletta, M.A. (deposition date: 2024-08-07, release date: 2024-12-04, Last modification date: 2024-12-18) |
| Primary citation | Batka, A.E.,Thomas, W.C.,Tudorica, D.A.,Sayler, R.I.,Marletta, M.A. Second-Sphere Histidine Catalytic Function in a Fungal Polysaccharide Monooxygenase. Biochemistry, 63:3136-3146, 2024 Cited by PubMed Abstract: Fungal polysaccharide monooxygenases (PMOs) oxidatively degrade cellulose and other carbohydrate polymers via a mononuclear copper active site using either O or HO as a cosubstrate. Cellulose-active fungal PMOs in the auxiliary activity 9 (AA9) family have a conserved second-sphere hydrogen-bonding network consisting of histidine, glutamine, and tyrosine residues. The second-sphere histidine has been hypothesized to play a role in proton transfer in the O-dependent PMO reaction. Here the role of the second-sphere histidine (H157) in an AA9 PMO, PMO9E, was investigated. This PMO is active on soluble cello-oligosaccharides such as cellohexaose (Glc6), thus enabling kinetic analysis with the point variants H157A and H157Q. The variants appeared to fold similarly to the wild-type (WT) enzyme and yet exhibited weaker affinity toward Glc6 than WT (WT = 20 ± 3 μM). The variants had comparable oxidase (O reduction to HO) activity to WT at all pH values tested. Using O as a cosubstrate, the variants were less active for Glc6 hydroxylation than WT, with H157A being the least active. Similarly, H157Q was competent for Glc6 hydroxylation with HO, but H157A was less active. Comparison of the crystal structures of H157Q and WT PMO9E reveals that a terminal heteroatom of Q157 overlays with N of H157. Altogether, the data suggest that H157 is not important for proton transfer, but support a role for H157 as a hydrogen-bond donor to diatomic-oxygen intermediates, thus facilitating catalysis with either O or HO. PubMed: 39563485DOI: 10.1021/acs.biochem.4c00527 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.8 Å) |
Structure validation
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