Structure and catalytic mechanistic insight into Enterobacter aerogenes acetolactate decarboxylase

Publication date: Available online 5 March 2019Source: Enzyme and Microbial TechnologyAuthor(s): Fangling Ji, Yanbin Feng, Mingyang Li, Feida Long, Yongliang Yang, Tianqi Wang, Jingyun Wang, Yongming Bao, Song XueAbstractα-Acetolactate decarboxylase (ALDC) catalyses α-acetolactate into acetoin (3-hydroxy-2-butanone, AC) and is considered to be the rate-limiting enzyme in the synthesis of 2,3-butanediol. In this work, the enzymatic activity of ALDC from Enterobacter aerogenes ALDC (E.a.-ALDC) was fully characterized with enzyme kinetics, indicating a Km of 14.83 ± 0.87 mM and a kcat of 0.81 ± 0.09 s-1. However, compared with the activities of ALDCs reported from other bacteria, the activity of E.a.-ALDC was determined to present a relatively lower value of 849.08 ± 35.21 U/mg. The enzyme showed maximum activity at pH 5.5. In addition, the activity of E.a.-ALDC was promoted by Mg2+. The crystal structure of E.a.-ALDC firstly solved by X-ray crystallography at resolution of 2.4 Å revealed a chelated zinc ion with conserved His199, His201, His212, Glu70 and Glu259. In the active center, the conservative Arg150 was particularly proven to deviate from the zinc ion of the active centre, by adopting a flexible conformational change, resulting in a weak interaction network of the enzyme and the substrate. Further in silico docking of E.a.-ALDC with two enantiomers, (R)-acetolactate and (S)-acetolactate, unaltered the interaction network of E.a.-ALDC from the apo ...

Source: Enzyme and Microbial Technology - March 6, 2019 Category: Biotechnology Source Type: research