The Department of Biochemistry's weekly BCH 252 seminar series is presented this week by:

Tynan Young, BCMB Graduate Student, UC Riverside 

Seminar Title: "Crystallographic Determination of the Structure of the Small and Medium Subunits of FdsABG Formate Dehydrogenase from C. necator"

Abstract: 

The cytosolic, NAD+-dependent formate dehydrogenase (FdsABG) found in the soil bacterium C. necator and catalyzes the oxidation of formate to CO2. Electrons within the system are passed from the active site down through 7 probable Fe-S sites, then to an FMN cofactor and eventually passed onto an NAD+ cofactor, forming NADH. The active site consists of a Molybdenum atom held in place by two equivalents of a pterin cofactor, representative of the DMSO reductase subfamily of Mo-containing enzymes. This enzyme within the Mo-containing family of enzymes is somewhat unique in that it is located biologically within the cytoplasm as opposed to the many other periplasmic and membrane-bound dehydrogenases (such as DMSO reductase, arsenite oxidase and formate dehydrogenases N and O found in E. coli). Subunits FdsB and FdsG have been found to have sequence homology (30-40%) to the NADH dehydrogenase subunits of T. thermophilus, subunits 2 and 1, respectively. The large subunit, FdsA has been found to have sequence homology (about 40%) to the cytosolic formate dehydrogenase H of E. coli.

Single Anomalous Diffraction (SAD) X-ray crystallography experiments in conjunction with Native, or non-anomalous, experiments were utilized to determine a portion of FdsABG’s structure - particularly FdsB and FdsG. The structure of these subunits was characterized and evaluated against the sequence homologs Nqo2 and Nqo1 of NADH dehydrogenase subunits of T. thermophilus.