EC Number |
Protein Variants |
Reference |
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1.1.1.3 | more |
generation of a knockout homoserine dehydrogenase (HSD) mutant by chemical mutagenesis. Auxotrophic mutant formed from ddh gene, encoding diaminopimelate dehydrogenase, recombinantly expressed in Corynebacterium glutamicum strain ATCC 13032 with blocked HSD shows increased yield of L-lysine of 24.89 g/l compared to ddh gene expressed in wild-type strain ATCC 13032 (20.66 g/l of L-lysine). The maximum yield of L-lysine for the auxotrophic mutant is attained at pH 7.5 and 30°C after 96 h incubation time. Method optimization, overview |
-, 762359 |
1.1.1.3 | more |
generation of HOM6-deleted (HOM6/hom6DELT and hom6DELTA/hom6DELTA) and HOM6-reintegrated (hom6DELTA/hom6DELTA::HOM6 and hom6DELTA::HOM6/hom6DELTA::HOM6) strains |
-, 740860 |
1.1.1.3 | more |
heterologous expression in a hom-negative Escherichia coli mutant Gif 102, not able to grow on minimal medium unless added 1.5 mM of both L-threonine and L-methionine results in strains growing well on minimal agar plates without added threonine and methionine |
-, 710978 |
1.1.1.3 | more |
key metabolic pathway for construction of an inducer-free L-homoserine-producing strain to maximize the productivity of L-homoserine based on genetic-engineering tools, comparison of L-homoserine production, cell growth, and glucose consumption in different engineered strains, overview. L-Homoserine is a nonessential amino acid for the biosynthesis of L-threonine and L-methionine. It is also an important precursor for the production of isobutanol, 1,4-butanediol, L-phosphinothricin, 2,4-ihydroxybutyrate, and 1,3-propanediol. The initial L-homoserine-producing strain HS1 is obtained by blocking the degradative and competitive pathways and overexpressing thrA (encoding homoserine dehydrogenase) based on an O-succinyl homoserine-producing strain, using the pull-push-block strategy, an efficient method to engineer microorganisms involved in biosynthesizing target products by modifying metabolic networks. L-homoserine-converting pathway-related genes (thrB, encoding homoserine kinase, and metA, encoding homoserine O-succinyltransferase) are successively deleted to block L-homoserine degradation. Gene thrA is overexpressed to push the carbon flux to L-homoserine production. Then, the lysine-auxotrophic strain HS2 is generated by deleting lysA to eliminate a precursor competing metabolic pathway on L-homoserine production. For strengthening the capability of the L-homoserine transport system and the transformation of other toxic intermediate metabolites, gene rhtA, encoding the inner membrane transporter that is involved in the export of L-homoserine, is overexpressed chromosomally by replacing the native promoter with the trc promoter to obtain strain HS3 (Trc-rhtA). The strain shows increased activity. Increase in the L-homoserine export capacity and relieve the growth burden of homoserine-producing strains to enable survival via replacement of the native promoter of the eamA gene by the trc promoter in strain HS4 (Trc-eamA). Two rhtA gene copies (the native rhtA gene and replacement of the lacI gene) and eamA are overexpressed under the trc promoter in the chromosome to construct strain HS5 (DELTAlacI::Trc-rhtA Trc-rhtA Trc-eamA). Under batch culture, strain HS5, with modification of the transport system and construction of a constitutive expression system, can produce 3.14 g/l L-homoserine, which is 54.2% higher than strain HS2 production. In addition, the specific production of strain HS5 is also increased. Repression of candidate genes by the CRISPRi system to further enhance L-homoserine production |
-, 760402 |
1.1.1.3 | more |
mutant strain M20-20D is deficient in gene HOM6 and shows no activity, the defect can be complemented by recombinant expression of the Arabidopsis thaliana gene akthr2 in the mutant yeast cells |
657018 |
1.1.1.3 | more |
releasing the enzymes of the L-threonine biosynthesis pathway from feedback control and coordinating their expression plays a pivotal role in engineering Corynebacterium glutamicum into L-isoleucine producers, construction of transgenic Corynebacterium glutamicum with deregulated L-threonine biosynthesis pathway enzymes for enhanced L-isoleucine biosynthesis |
-, 738802 |
1.1.1.3 | P458S |
site-directed mutagenesis, strain HS33/pACYC-pycP458S-thrAG433R-lysC shows increased activity (62.4% of the maximum theoretical yield) |
-, 760402 |
1.1.1.3 | Q443A |
site-directed mutagenesis, altered reaction kinetics for both activities and altered inhibition pattern by L-threonine compared to the wild-type enzyme, asparate kinase activity is completely insensitive to inhibition by L-threonine, overview |
642341 |
1.1.1.3 | Q524A |
site-directed mutagenesis, altered reaction kinetics for both activities and altered inhibition pattern by L-threonine compared to the wild-type enzyme, overview |
642341 |
1.1.1.3 | R40A |
site-directed mutagenesis, in contrast to the wild-type enzyme, the mutant enzyme shows catalytic activity with NADP+, the activity with NAD+ is decreased compared to the wild-type enzyme |
-, 741408 |