关键词：
GENETICS
MOLYBDENUM COFACTOR
NITRATE REDUCTASE
NITRATE TRANSPORT
NITRITE REDUCTASE
摘要：
Nitrate uptake and reduction are highly regulated processes. In many plant species, nitrate uptake is induced by nitrate. Little, however, is known about the genetic and molecular aspects of nitrate transport. Reduction of nitrate to ammonia is carried out by nitrate and nitrite reductases. Nitrate and light enhance expression of the nitrate and nitrite reductase genes in most species. Mutants have been selected and characterized to identify genes controlling nitrate reductase in several higher plant species. Six loci are known to control the synthesis or assembly of the molybdenum cofactor of nitrate reductase, xanthine dehydrogenase and aldehyde oxidase. The nitrate reductase apoenzyme is encoded by a single gene, except in allopolyploid species and in those species possessing both NADH-specific and NAD(P)H-bispecific nitrate reductases. Comparison of NADH-specific nitrate reductase amino acid sequences deduced from cloned genes reveals considerable sequence conservation in regions believed to encode the functional domains of nitrate reductase, but less conservation in the N-terminal and hinge regions of the enzyme. For both nitrate and nitrite reductases, sequence identity is greater among species of the same subclass than between Monocotyledoneae and Dicotyledoneae subclass species.
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中文科技期刊
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