Escherichia coli formate dehydrogenase mutants with altered selenopolymer profiles

Four classes of Escherichia coli mutants deficient in either or both of their anaerobic selenium-containing formate dehydrogenases (FDH) were isolated. A class I mutant devoid of FDH_H activity specifically linked to benzyl viologen (BV) produced a small amount of the FDH_H 80,000 dalton selenopeptide. Three class II mutants were deficient in FDH_N activity specifically linked to phenazine methosulfate (PMS) and exhibited a selenopeptide doublet rather than the FDH_N 110,000 dalton selenosubunit. Three class III mutants were selenium incorporation deficient and did not exhibit either FDH activity or ⁷⁵Selabeled selenopolymers. A class IV mutant was devoid of PMS-linked FDH_N activity; neither its FDH_N 110,000 dalton selenosubunit nor its BV-linked FDH_H activity was fully regulated by nitrate.Abbreviations FDH formate dehydrogenase - BV benzyl viologen - MV methyl viologen - PMS phenazine methosulfate - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis