Article Abstract:
Dairy lactococcal strains without the enzyme acetolactate decarboxylase (Ald) have been isolated by introducing genes that encode enzymes involved in the biosynthesis of branched-chain amino acids. Ald regulates the alpha-acetolactate pool in pyruvate catabolism and in the synthesis of isoleucine, leucine and valine (ILV). These mutants can be selected as leucine-resistant mutants in ILV- or IV-prototrophic strains. Western blotting with Ald-specific antibodies was used in detecting the presence of Ald in the mutants.
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Article Abstract:
The in vitro chemical mutagenesis of the cloned Escherichia coli aroG gene identifies the residues and regions of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase that are essential for phenylalanine (Phe) feedback inhibition. Mutations at the D146N and P150L residues abolish the inhibition of the synthase by Phe. The study indicates that the 146-150 residues constitute an aromatic acid-binding site that is necessary for Phe-induced suppression.
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Article Abstract:
Researchers introduced a gene for herbicide resistance into E. coli by fusing the gene for acetolactate synthase II to the DnaE intein from Synechocystis sp. strain PCC6803. The DnaE intein reconstitutes a functional protein via trans-splicing.
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