Role of introduced surface cysteine of NADH oxidase from Lactobacillus rhamnosus.

Autor: Li FL; School of Pharmacy, United Pharmaceutical Institute of Jiangsu University and Shandong Tianzhilvye Biotechnology Co. Ltd., Jiangsu University, Zhenjiang 212013, People's Republic of China., Tao QL; School of Pharmacy, United Pharmaceutical Institute of Jiangsu University and Shandong Tianzhilvye Biotechnology Co. Ltd., Jiangsu University, Zhenjiang 212013, People's Republic of China., Liu CY; School of Pharmacy, United Pharmaceutical Institute of Jiangsu University and Shandong Tianzhilvye Biotechnology Co. Ltd., Jiangsu University, Zhenjiang 212013, People's Republic of China., Gao J; College of Petroleum and Chemical Engineering, Beibu Gulf University, Qinzhou 535011, People's Republic of China., Zhang YW; School of Pharmacy, United Pharmaceutical Institute of Jiangsu University and Shandong Tianzhilvye Biotechnology Co. Ltd., Jiangsu University, Zhenjiang 212013, People's Republic of China; College of Petroleum and Chemical Engineering, Beibu Gulf University, Qinzhou 535011, People's Republic of China. Electronic address: zhangyewang@ujs.edu.cn.
Jazyk: angličtina
Zdroj: International journal of biological macromolecules [Int J Biol Macromol] 2019 Jul 01; Vol. 132, pp. 150-156. Date of Electronic Publication: 2019 Mar 26.
DOI: 10.1016/j.ijbiomac.2019.03.168
Abstrakt: Cysteine, a critical residue for catalytic process but also vulnerable to oxidative damage, was conventionally expressed as a buried catalytic site in most redox enzymes. In the present work, specific surface-exposed sites of a NADH oxidase from Lactobacillus rhamnosus (LrNox) were selected and mutated to cysteine to investigate its effects on catalytic function because LrNox has a buried catalytic cysteine but no surface-exposed one. The results showed that exception of the sites on dimer interface, the activities of LrNox mutants were improved to vary degrees when the polar uncharged and alanine residues were mutated to cysteine. But the cysteine mutations of polar charged and nonpolar residues except alanine showed obvious decline in catalytic activity. Substituting of Ala85 and Thr96 with other residues suggested that the cysteine mutation showed the highest activity. Structural analysis suggested that even a single cysteine mutation on the specific non-conserved surface area of LrNox could induce changes on the conformation of catalytic cysteine and lower the activation free energy to improve the catalytic activity.
(Copyright © 2019 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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