(11) announced the discovery of ferredoxin (Fd), a small iron-sulfur (FeS) protein of low redox potential, from Clostridium pasteurianum, and demonstrated it to be a physiological electron carrier for clostridial hydrogenase (reaction 1).
(2002) Genetic analysis of the archaeon Methanosarcina barkeri Fusaro reveals a central role for Ech hydrogenase and ferredoxin in methanogenesis and carbon fixation.
(2009) The iron hydrogenase of Thermotoga maritima utilizes ferredoxin and NADH synergistically: a new perspective on anaerobic hydrogen production.
Consistent with this idea, multiple hydrogenosomal fermentation enzymes--including ferredoxin, succinyl-CoA synthetase, and malic enzyme--resemble their counterparts in mitochondria (Johnson et al., 1990; Hrdy and Muller, 1995b).
An iron-dependent hydrogenase (Fe-hydrogenase), which gives the hydrogenosome its name, transfers electrons from reduced ferredoxin to two protons to make hydrogen gas (Lindmark and Muller, 1973; Muller, 1993; Payne et al., 1993; Bui and Johnson, 1996; Homer et al., 2000).
The reduced ferredoxin is produced within the hydrogenosome by pyruvate:ferredoxin oxidoreductase (PFOR), which decarboxylates pyruvate to acetyl-CoA and [CO.sub.2] (Lindmark and Muller, 1973; Muller, 1993; Payne et al., 1993; Hrdy and Muller, 1995a; Homer et al., 1999).
histolytica EST (GenBank AB002772), which encodes the N-terminus of a putative short Fe-hydrogenase 1, was identified from GenBank using BLASTP and an amebic 2[4Fe4S] ferredoxin sequence (Altschul et a!., 1997; Nixon et al., 2002).
lamblia genes encoding short Fe-hydrogenase, malic enzyme, alcohol dehydrogenase E (ADHE), and ferredoxin 1 (entamoebas only) (Rosenthal et al., 1997; Nixon et al., 2002).