5.4.3.8 K272A mutant enzyme Lys272Ala is inactive 3421 5.4.3.8 K286A site-directed mutagenesis -, 747005 5.4.3.8 L265E mutant Lys265Arg has 2% of the enzymatic activity compared to the wild-type enzyme, the dimeric structure is not influenced, activity is stimulated by addition of exogenous amines such as ethanolamine and methylamine 3432 5.4.3.8 M248I the M248I point mutation confers about 100fold increased gabaculine resistance to GSAM 703619 5.4.3.8 additional information gabaculine-resistant mutant enzyme with a 3 times lower catalytic efficiency and impaired prototropic rearrangement and transaldimination 3430 5.4.3.8 additional information improved biological production of 5-aminolevulinate in Corynebacterium glutamicum is achieved by overexpressing the glutamate-initiated C5 pathway. Copies of the glutamyl t-RNA reductase HemA from several bacteria (Corynebacterium glutamicum, Escherichia coli, Bacillus subtilis, Salmonella typhimurium, and Klebsiella pneumoniae) are mutated by site-directed mutagenesis of which a HemA version from Salmonella typhimurium exhibits the highest 5-aminolevulinate production. Cultivation of the HemA-expressing strain produces approximately 204 mg/l of 5-aminolevulinate, while co-expression with HemL (glutamate-1-semialdehyde amino-transferase) increases 5-aminolevulinate concentration to 457 mg/L, representing 11.6fold and 25.9fold increases over the control strain (17 mg/l of 5-aminolevulinate). 5-Aminolevulinate overproduction can also be increased by reducing the formation of heme, which has been shown to have inhibitory effects on HemA activity. Method evaluation and optimization, overview -, 747678