Significance of Arg3, Arg54, and Tyr58 of L-aspartate α-decarboxylase from Corynebacterium glutamicum in the process of self-cleavage
2014
Cui, Wenjing | Shi, Zengxiu | Fang, Yueqin | Zhou, Li | Ding, Ning | Zhou, Zhemin
PURPOSE OF WORK: We have elucidated the significance of three key amino acid residues of L-aspartate α-decarboxylase that act remotely from its cleavage site for its functional self-cleavage as well as for its catalytic activity. These results provide useful fundamental information for engineering L-aspartate α-decarboxylase. L-Aspartate α-decarboxylase (ADC) from Corynebacterium glutamicum, and encoded by panD, was cloned and expressed in Escherichia coli and then purified. Three amino acid residues were found to be related to ADC self-cleavage. Mutating R3 to either A, Q, N, L, D, or E produced only the unprocessed pro-enzyme. Although mutating R54 and Y58 into A or K and A or T, respectively, partly influenced ADC self-cleavage, the specific activity of each of the four ßmutants decreased to 3.5, 4, 2.4, and 2.6 U mg⁻¹, respectively, compared with a specific activity of 690 U mg⁻¹for the wild-type enzyme. Thus, R3 triggers ADC self-cleavage and completes the modification of the active site with assistance by R54 and Y58. These results will help to engineer ADC for improved industrial applications.
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