Disease relevance of nadB

• Molecular biology of pyridine nucleotide biosynthesis in Escherichia coli. Cloning and characterization of quinolinate synthesis genes nadA and nadB [1].
• Here we report on the expression of the nadB gene under control of the inducible left promoter of the bacteriophage lambda [2].
• Identification of rpoE and nadB as host responsive elements of Yersinia enterocolitica [3].

High impact information on nadB

• L-Aspartate oxidase, a newly discovered enzyme of Escherichia coli, is the B protein of quinolinate synthetase [4].
• In its role as B protein in quinolinic acid synthetase, product formation (quinolinic acid) is linear with protein concentration; however, when it functions as an L-aspartate oxidase, product formation (oxaloacetate) is a parabolic function of protein concentration [4].
• The L-aspartate oxidase and B protein activities of the enzyme are inhibited by NAD+, which is competitive with FAD [4].
• Analysis of a collection of deletions in oriT indicated that the nucleotide sequences immediately surrounding the nic site are important, but not the only essential feature, for the nicking reaction [5].
• L-Aspartate oxidase is a very particular oxidase which behaves as a fumarate reductase in anaerobic conditions [6].

Chemical compound and disease context of nadB

• The two genes, nadA and nadB, responsible for quinolinate biosynthesis from aspartate and dihydroxyacetone phosphate in Escherichia coli were cloned and characterized [1].
• Redox potentials and quinone reductase activity of L-aspartate oxidase from Escherichia coli [7].
• NAD derives from quinolinic acid which is synthesized in Escherichia coli from L-aspartate and dihydroxyacetone phosphate (DHAP) as the result of the concerted action of two enzymes, L-aspartate oxidase (NadB) and quinolinate synthetase (NadA) [8].
• L-aspartate oxidase from Escherichia coli. II. Interaction with C4 dicarboxylic acids and identification of a novel L-aspartate: fumarate oxidoreductase activity [9].

Biological context of nadB

• The enzyme was purified to homogeneity in a three-step procedure and the reading frame of the L-aspartate oxidase gene was confirmed by Edman degradation of five cyanogen bromide peptides [2].
• Probing the active site of L-aspartate oxidase by site-directed mutagenesis: role of basic residues in fumarate reduction [6].
• Steady-state kinetics for the oxidase and the fumarate reductase activity of L-aspartate oxidase were obtained using either fumarate or oxygen as electron acceptor and L-aspartate as electron donor [9].
• Characterization of an efficient gene cloning strategy for Aspergillus niger based on an autonomously replicating plasmid: cloning of the nicB gene of A. niger [10].
• A nicB-deficient A. niger was complemented by co-transformation with pAB4-ARp1 and an A. niger cosmid library [10].

Associations of nadB with chemical compounds

• This result perfectly explains why L-aspartate oxidase may be considered as a very particular fumarate reductase unable to use succinate as the electron donor [7].
• L-Aspartate oxidase binds menadione and 2, 3-dimethoxy-5-methyl-p-benzoquinone with Kd values of 11.5 and 2.4 microM, respectively [7].
• A new fumarate reductase activity of L-aspartate oxidase is reported using benzylviologen or L-aspartate as reductants and fumarate as oxidant [9].
• Moreover the data reported in this manuscript suggest that NAD inhibits l-aspartate oxidase activity by competing with the flavin for the binding to the enzyme [11].
• L-Aspartate oxidase was subjected to product inhibition since iminoaspartate, which results from the oxidation of L-aspartate, binds to the enzyme with a dissociation constant (Kd) equal to 1.4 microM [12].

Other interactions of nadB

• Adjacent to cooA are two genes, nadB and nadC, with predicted products similar to proteins in other bacteria that catalyze reactions in the de novo synthesis of NAD.(ABSTRACT TRUNCATED AT 250 WORDS)[13]
• We describe the identification of the Yersinia enterocolitica rpoE gene, which encodes the alternative sigma factor sigmaE, and the divergently transcribed nadB gene, as genes that are expressed during infection of mice [3].

Analytical, diagnostic and therapeutic context of nadB

• Crystallization of L-aspartate oxidase, the first enzyme in the bacterial de novo biosynthesis of NAD [14].

References