Microbial reduction of selenate and nitrate: common themes and variations.
A number of biochemically distinct systems have been characterized for the microbial reduction of the oxyanions, selenate (SeO(4)(2-)) and nitrate (NO(3)(-)). Two classes of molybdenum-dependent nitrate reductase catalyse the respiratory-linked reduction of nitrate (NO(3)(-)) to nitrite (NO(2)(-)). The main respiratory nitrate reductase (NAR) is membrane-anchored, with its active site facing the cytoplasmic compartment. The other enzyme (NAP) is water-soluble and located in the periplasm. In recent years, our understanding of each of these enzyme systems has increased significantly. The crystal structures of both NAR and NAP have now been solved and they provide new insight into the structure, function and evolution of these respiratory complexes. In contrast, our understanding of microbial selenate (SeO(4)(2-)) reduction and respiration is at an early stage; however, similarities to the nitrate reductase systems are emerging. This review will consider some of the common themes and variations between the different classes of nitrate and selenate reductases.
Watts
C A
CA
Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK.
Ridley
H
H
Dridge
E J
EJ
Leaver
J T
JT
Reilly
A J
AJ
Richardson
D J
DJ
Butler
C S
CS
D000595:Amino Acid Sequence; D001673:Biodegradation, Environmental; D002462:Cell Membrane / Q000201:enzymology; D008969:Molecular Sequence Data; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000737:chemistry / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D019897:Periplasm / Q000201:enzymology; D064586:Selenic Acid; D018036:Selenium Compounds / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D009566:Nitrates; D018036:Selenium Compounds; D010088:Oxidoreductases; D009565:Nitrate Reductases; D050901:Nitrate Reductase; C078108:selenate reductase; D064586:Selenic Acid