鲍曼不动杆菌核苷二磷酸激酶的结构和功能研究（英文）  

Structural and Functional Characterization of Acinetobacter baumannii Nucleoside Diphosphate Kinase

作　　者：胡颖嵩[1,2] 冯峰[1] 刘迎芳[1] 

机构地区：[1]中国科学院生物物理研究所,北京100101 [2]中国科学院大学,北京100049

出　　处：《生物化学与生物物理进展》2015年第3期260-267,共8页Progress In Biochemistry and Biophysics

基　　金：supported by grants from National Basic Research Program of China(2011CB910304,2012CB910204)~~

摘　　要：近年来,鲍曼不动杆菌(Acinetobacter baumannii)在医院里越来越受到人们的关注,尤其是在重症监护病房(ICUs).它以强大的多重耐药性(multiresistance)而闻名.核苷二磷酸激酶(nucleoside diphosphate kinase,NDK)是一种进化上非常保守的酶,它能催化核苷之间磷酸基团的转移.我们解析了鲍曼不动杆菌NDK野生型和C端氨基酸残基Arg141-Thr142-Arg143(RTR)截短突变体的结构.通过和黄色黏菌(Myxococcus xanthus)NDK的三维结构进行比较,推断鲍曼不动杆菌NDK的催化机制和黄色黏菌类似.通过激酶活性实验和圆二色谱实验,发现鲍曼不动杆菌NDK E28A突变体二级结构发生了改变,从而导致蛋白催化活性降低,说明Glu28是鲍曼不动杆菌NDK结构中非常关键的氨基酸残基.鲍曼不动杆菌NDK C端RTR截短突变体显示出催化活性极大的降低,这可能与C端RTR残基介导的二体间相互作用有关.虽然RTR截短突变体中的Lys33伸向了和野生型中不同的方向,和Val15产生相互作用弥补了一部分因为RTR截短丢失的相互作用,维持了RTR截短突变体和野生型类似的结构.但是,Lys33产生的相互作用依然太弱,不足以维持蛋白在催化的动态过程中整体结构的高效转换.我们解析的鲍曼不动杆菌NDK晶体高分辨率结构将有助于科学家设计针对鲍曼不动杆菌的药物.Acinetobacter baumannii is a new threat in intensive care units（ICUs） for its multiresistance to antibiotics, but little is known about this bacterium. Nucleoside diphosphate kinase（NDK） is an evolutionarily conserved enzyme that catalyzes phosphoryl transformation between nucleosides. In our study, the crystal structure of wild type Acinetobacter baumannii NDK along with its mutant generated through truncation of the C-terminal arginine-threonine-arginine（RTR） residues, were solved. In comparison with Myxococcus xanthus NDK structure, we speculated that Acinetobacter baumannii NDK shared a similar catalytic mechanism with Myxococcus xanthus. Activity assay and CD spectra analysis revealed that E28 A mutant might interrupt the secondary structure of the protein leading to declined enzymatic activity. Truncation of the C-terminal RTR residues would lead to the instability of the tertiary structure resulting in reduced kinase activity. Lys33 was a key residue for maintaining dimer interaction when RTR residues were truncated but was not sufficient to keep efficient enzymatic reaction. The structural data can provide a potential target to develop novel therapeutic approaches to overcome multiresistance of the bacterium against antibiotics.

关 键 词：鲍曼不动杆菌 核苷二磷酸激酶(NDK) 晶体结构 

分 类 号：Q5[生物学—生物化学] Q6