Computation-aided rational design of a halophilic choline kinase for cytidine diphosphate choline production in high-salt condition

Publication date: Available online 13 November 2018Source: Journal of BiotechnologyAuthor(s): Cheng Zheng, Zhenjian Li, Haifeng Yang, Tianyi Zhang, Huanqing Niu, Dong Liu, Junzhi Wang, Hanjie YingAbstractBiocatalysis has become the main approach to produce cytidine diphosphate choline (CDP-choline), which has been applied for treatment of acute craniocerebral injury and consciousness after brain surgery. However, salt accumulates with the production and inhibits enzyme activity, and eventually reduces yield and product accumulation rate. Our work provided a possible solution to this problem by applying a computational designed halophilic choline kinase. The halotolerant CKI (choline kinase) was designed following a unique strategy considering the most variable residue positions on the protein surface among target enzymes from different sources. The basic and neutral surface residues were replaced with acidic ones. This approach was enlightened by features of natural halophilic enzymes. Mutants in the work represented higher catalytic activities and IC50 (inhibit activity by 50 %) at high salt concentrations (over 1200 mM). Furthermore, when the mutant was used in fed-batch production, the CDP-choline accumulation rate doubled comparing with process using wild-type CKI at acetate concentration of over 700 mM. The maximum titer was 151 ± 3.2 mM, the productivity was 5.8 ± 0.1 mM·L-1 h−1, and molar yield to CMP and utilization efficiency of energy were 85....
Source: Journal of Biotechnology - Category: Biotechnology Source Type: research