Table 1 Summary of the features of some representative formate dehydrogenases and Nformyl-methanofuran dehydrogenases
Enzyme
Active
site
a
Subunit
composition
Notes
Clostridium
carboxidivorans FDH
W
SeCys
a
W, [4Fe–4S]
• cytoplasmatic?
• NAD
+ -dependent
Thermoanaerobacter
kivui FDH
• hydrogen-dependent CO 2
reductase
Desulfovibrio gigas
FDH
ab
a: W, [4Fe–4S]
b: 3 [4Fe–4S]
• periplasmatic
Desulfovibrio
alaskensis FDH
Desulfovibrio
vulgaris
FDH
Moorella
thermoacetica FDH
(ab) 2
a: W, [4Fe–4S]
b: 3 [4Fe–4S]
• cytoplasmatic
• NADP
+ -dependent
Synthrobacter
fumaroxidans FDH
(abc) 2
W, Fe
• periplasmatic?
Methylobacterium
extorquens FDH
W
Cys
ab
a: W, ! 1 Fe/S
b: [4Fe–4S],
FMN
• cytoplasmatic
• NAD
+ -dependent
Escherichia coli
FDH H
Mo
SeCys
a
Mo, [4Fe–4S]
• cytoplasmatic
(membrane-bound via its partners)
• partner of formate-hydrogen lyase
system
Acetobacterium
woodii FDH
• hydrogen-dependent CO 2
reductase
Desulfovibrio
desulfuricans FDH
abc
a: Mo, [4Fe–4S]
b: 3 [4Fe–4S]
c: 4 c haems
• periplasmatic
Desulfovibrio
vulgaris FDH
Escherichia coli FDH
N
(abc) 3
a: Mo, [4Fe–4S]
b: 4 [4Fe–4S]
c: 2 b haems
• membrane-bound
periplasm-faced
• partner in anaerobic
nitrate-formate
respiratory system
Escherichia coli FDH
O
• membrane-bound
periplasm-faced
• partner in nitrate-formate
respiratory system during aerobic
to anaerobic transition
(continued)
Carbon Dioxide Utilisation—The Formate Route
37