| Autor: |
Flachmann, Ralf, Kunz, Norbert, Seifert, Jochen, Gütlich, Markus, Wientjes, Franz-Josef, Läufer, Albrecht, Gassen, Hans Günter |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; 8/1/88, Vol. 175 Issue 2, p221-228, 8p, 6 Diagrams, 3 Charts |
| Abstrakt: |
The two genes, nadA and nadB, responsible for quinolinate biosynthesis from aspartate and dihydroxyacetone phosphate in Escherichia coli were cloned and characterized, Quinolinate (pyridine-2,3-dicarboxylate) is the biosynthetic precursor of the pyridine ring of NAD, Gene nadA was identified by complementation in three different nadA mutant strains. Sequence analysis provided an 840-bp open reading frame coding for a 31 555-Da protein. Gene nadB was identified by complementation in a nadB mutant strain and by the L-aspartate oxidase activity of its gene product. Sequence analysis showed a 1620-bp open reading frame coding for a 60306-Da protein. For both genes, promoter regions and ribosomal binding sites were assigned by comparison to consensus sequences. The nadB gene product, L-aspartate oxidase, was purified to homogeneity and the N-terminal sequence of 19 amino acids was determined. The enzyme was shown to be specific for L-aspartate, High-copy-number vectors, carrying either gene nadA, nadB or nadA + nadB, increased quinolinate production 1,5-fold, 2,0-fold and 15-fold respectively. Both gene products seem to be equally rate-limiting in quinolinate synthesis. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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