Methionine sulfoxide reductase in Helicobacter pylori:: Interaction with methionine-rich proteins and stress-induced expression
Methionine sulfoxide reductase in Helicobacter pylori:: Interaction with methionine-rich proteins and stress-induced expression
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DOI：
10.1128/jb.00430-06
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发表时间：
2006-08-01
影响因子：
3.2
通讯作者：
Maier, Robert J.
中科院分区：
文献类型：
--
作者：
Alamuri, Praveen;Maier, Robert J.
甲硫氨酸亚砜还原酶对氧化甲硫氨酸残基的还原性修复对于幽门螺杆菌维持胃内定植具有重要意义。通过使用免疫共沉淀方法，从全细胞提取物（细胞暴露于O-2应激后）中鉴定出Msr修复靶向的含甲硫氨酸蛋白。被鉴定为Msr相互作用的蛋白质包括过氧化氢酶、GroEL、硫氧还蛋白-1（Trx 1）和位点特异性重组酶;除了一个例外（Trx 1，Msr的还原剂），所有这些蛋白质的甲硫氨酸（Met）含量都比其他蛋白质高出约两倍。纯化这些富含Met的蛋白质，并显示其与Msr单独形成交联加合物。过氧化氢酶的特定活性在一个msr菌株的亲本菌株的一半，这种差异仅在氧化应激条件下观察到，并通过添加Msr加二硫苏糖醇msr菌株提取物的活性恢复到接近野生型的水平。与交联研究一致，纯Msr使用Trx 1而不是Trx 2作为还原剂。比较结构模型将H.幽门螺杆菌Msr属于MsrB家族中的II类，如奈瑟氏菌酶。纯H. pylori酶仅还原甲基对甲苯基亚砜的R异构体，对底物的表观Km为4.1 mM。应激条件（过氧化物，过氧亚硝酸盐，铁饥饿）都引起大约3至3.5倍的转录上调msr。无论是在生长过程中的O-2水平，也没有使用背景调节突变体有一个显着的影响msr转录。晚期对数和稳定期培养物具有最高的Msr蛋白水平和比活性。
The reductive repair of oxidized methionine residues performed by methionine sulfoxide reductase is important for the gastric pathogen Helicobacter pylori to maintain persistent stomach colonization. Methionine-containing proteins that are targeted for repair by Msr were identified from whole-cell extracts (after cells were exposed to O-2 stress) by using a coimmunoprecipitation approach. Proteins identified as Msr-interacting included catalase, GroEL, thioredoxin-1 (Trx1), and site-specific recombinase; with one exception (Trx1, the reductant for Msr) all these proteins have approximately twofold higher methionine (Met) content than other proteins. These Met-rich proteins were purified and were shown to individually form a cross-linked adduct with Msr. Catalase-specific activity in an msr strain was one-half that of the parent strain; this difference was only observed under oxidative stress conditions, and the activity was restored to nearly wild-type levels by adding Msr plus dithiothreitol to msr strain extracts. In agreement with the cross-linking study, pure Msr used Trx1 but not Trx2 as a reductant. Comparative structure modeling classified the H. pylori Msr in class II within the MsrB family, like the Neisseria enzymes. Pure H. pylori enzyme reduced only the R isomer of methyl p-tolyl-sulfoxide with an apparent K-m of 4.1 mM for the substrate. Stress conditions (peroxide, peroxynitrite, and iron starvation) all caused approximately 3- to 3.5-fold transcriptional up-regulation of msr. Neither the O-2 level during growth nor the use of background regulatory mutants had a significant effect on msr transcription. Late log and stationary phase cultures had the highest Msr protein levels and specific activity.