Structural investigation of cellobiose dehydrogenase IIA: Insights from small angle scattering into intra- and intermolecular electron transfer mechanisms

• Published in: Biochimica et biophysica acta. General subjects Vol. 1862; no. 4; pp. 1031 - 1039
• Main Authors: Bodenheimer, Annette M., O'Dell, William B., Oliver, Ryan C., Qian, Shuo, Stanley, Christopher B., Meilleur, Flora
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2018; Elsevier
• Subjects: Ascomycota - enzymology; Ascomycota - genetics; BASIC BIOLOGICAL SCIENCES; calcium; Calcium - chemistry; Calcium - metabolism; carbohydrate binding; Carbohydrate Dehydrogenases - chemistry; Carbohydrate Dehydrogenases - genetics; Carbohydrate Dehydrogenases - metabolism; cations; cellobiose; cellobiose dehydrogenase; Cellulose - chemistry; Cellulose - metabolism; electron transfer; Electron Transport; fuel production; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - metabolism; Hydrogen-Ion Concentration; Intermolecular electron transfer (IeET); Intramolecular electron transfer (IaET); medical equipment; Modeling; Models, Molecular; Neurospora crassa; Neurospora crassa - enzymology; Neurospora crassa - genetics; neutrons; oxidation; Oxidation-Reduction; Oxidative cellulose degradation; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; polysaccharides; Protein Binding; Protein Conformation; Redox complex; Scattering, Small Angle; Small-angle scattering; X-radiation; X-Ray Diffraction; Intermolecular electron transfer (IeET); Small-angle scattering; Oxidative cellulose degradation; Intramolecular electron transfer (IaET); Modeling; Redox complex
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2018.01.016

Cellobiose dehydrogenases have gained interest due to their potential applications in sectors from biofuel production to biomedical devices. The CDHIIA variant is comprised of a cytochrome domain (CYT), a dehydrogenase domain (DH), and a carbohydrate-binding module (CBM) that are connected by two flexible linkers. Upon cellobiose oxidation at the DH, intramolecular electron transfer (IaET) occurs from the DH to the CYT. In vivo, CDHIIA CYT subsequently performs intermolecular electron transfer (IeET) to a lytic polysaccharide monooxygenase (LPMO). The relevant solution-state CDH domain conformations for IaET and IeET have not been fully characterized. Small-angle X-ray and neutron scattering measurements of oxidized CDHIIA from Myriococcum thermophilum and Neurospora crassa were performed to investigate the structural landscape explored in solution by MtCDHIIA and NcCDHIIA in response to cations, pH, and the presence of an electron acceptor, LPMO9D from N. crassa. The scattering data complemented by modeling show that, under oxidizing conditions, MtCDHIIA undergoes global conformational rearrangement in the presence of Ca2+. Oxidized NcCDHIIA exhibits conformational changes upon pH variation and, in the presence of NcLPMO9D, primarily adopts a compact conformation. These results demonstrate different conformational responses of oxidized MtCDHIIA and NcCDHIIA to changes in environment. The results also reveal a shift in the oxidized NcCDHIIA conformational landscape toward interdomain compaction upon co-incubation with NcLPMO9D. The present study is the first report on the structural landscapes explored in solution by oxidized cellobiose dehydrogenases under various cation concentrations, pH conditions and in the presence of an electron-accepting LPMO. •Interface electrostatics regulate the conformational landscape of Neurospora crassa and Myriococcum thermophilum CDHIIAs.•Neurospora crassa CDHIIA undergoes conformational changes upon pH variation.•Myriococcum thermophilum CDHIIA undergoes conformational changes in the presence of Ca2+.•Neurospora crassa CDHIIA adopts a compact conformation in the presence of Neurospora crassa LPMO9D.