Cloning, Sequence Analysis and Expression of Glutamate Dehydrogenase in Brevibacterium flavum GDK-9

Abstract:

The glutamate dehydrogenase (EC.1.4.1.4) gene which amplified from the genome of Brevibacterium flavum GDK-9 by polymerase chain reaction was linked with pUCm-T for sequence alignment. Analysis of gdh sequences revealed that the whole sequence is 1927 bp, only one ORF existed, which used ATG as the initiation codon and coded a peptide of 448 amino acids with a calculated molecular weight of 48 kD. The comparability between the cloned gdh sequence to the reported sequence is high to 99.55%. Only the 1190th base mutation (C→A) lead to the change of amino acid sequence (Thr→Asn), the others are not. The recombinant plasmid pXG was then transformed into E. coli XL-Blue and Brevibacterium flavum GDK-9 which was induced by IPTG. SDS-PAGE analysis revealed that there was a clear induced protein band with molecular mass of 48.7 kD on expected position. Standard glutamate fermentations indicated that although the level of GDH increases the intracellular glutamate pool, the level of GDH has no influence on glutamate secretion.