Morozova Elena A, Kulikova Vitalia V, Rodionov Alexei N, Revtovich Svetlana V, Anufrieva Natalya V, Demidkina Tatyana V
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova Str., 32, Moscow, 119991, Russia.
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova Str., 32, Moscow, 119991, Russia.
Biochimie. 2016 Sep-Oct;128-129:92-8. doi: 10.1016/j.biochi.2016.07.007. Epub 2016 Jul 16.
Antimicrobial activity of thiosulfinates in situ produced by mixtures of Citrobacter freundii methionine γ-lyase (MGL) with new substrates, l-methionine and S-(alkyl/allyl)-l-cysteine sulfoxides has been recently demonstrated (Anufrieva et al., 2015). This opens a way to the rational design of a new biotechnologically relevant antimicrobial drug producer. To increase the efficiency of the enzyme toward sulfoxides, the mutant forms of MGL, with the replacements of active site cysteine 115 with alanine (C115A MGL) and histidine (C115H MGL) were obtained. The replacement of cysteine 115 by histidine results in the loss of activity of the mutant enzyme in the γ-elimination reaction of physiological substrate, whereas the activity in the β-elimination reaction of characteristic substrates persists. However, the catalytic efficiency of C115H MGL in the β-elimination reaction of S-substituted l-cysteine sulfoxides is increased by about an order of magnitude compared to the wild type MGL. The antibacterial activity of C115H MGL mixtures with a number of sulfoxides was assessed against Gram-positive and Gram-negative bacteria. The bacteriostatic effect was more pronounced against Gram-positive than against Gram-negative bacteria, while antibacterial potential proved to be quite similar. Thus, the mutant enzyme C115H MGL is an effective catalyst, in particular, for decomposition of sulfoxides and the pharmacological couples of the mutant form with sulfoxides might be new antimicrobial agents.
最近已证明弗氏柠檬酸杆菌甲硫氨酸γ-裂合酶（MGL）与新底物L-甲硫氨酸和S-（烷基/烯丙基）-L-半胱氨酸亚砜混合物原位产生的硫代亚磺酸盐具有抗菌活性（阿努弗里耶娃等人，2015年）。这为合理设计一种新的具有生物技术相关性的抗菌药物生产商开辟了道路。为了提高该酶对亚砜的效率，获得了MGL的突变形式，即将活性位点半胱氨酸115替换为丙氨酸（C115A MGL）和组氨酸（C115H MGL）。用组氨酸替换半胱氨酸115会导致突变酶在生理底物的γ-消除反应中失去活性，而在特征底物的β-消除反应中的活性仍然存在。然而，与野生型MGL相比，C115H MGL在S-取代的L-半胱氨酸亚砜的β-消除反应中的催化效率提高了约一个数量级。评估了C115H MGL与多种亚砜混合物对革兰氏阳性菌和革兰氏阴性菌的抗菌活性。抑菌作用对革兰氏阳性菌比对革兰氏阴性菌更明显，而抗菌潜力证明相当相似。因此，突变酶C115H MGL是一种有效的催化剂，特别是对于亚砜的分解，并且突变形式与亚砜的药理组合可能是新型抗菌剂。
