Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
Antioxid Redox Signal. 2012 Nov 1;17(9):1190-200. doi: 10.1089/ars.2011.4304. Epub 2012 Mar 6.
The ability of pathogens to cope with the damaging effects of nitric oxide (NO), present in certain host niches and produced by phagocytes that support innate immunity, relies on multiple strategies that include the action of detoxifying enzymes. As for many other pathogens, these systems remained unknown for Helicobacter pylori. This work aimed at identifying and functionally characterizing an H. pylori system involved in NO protection.
In the present work, the hp0013 gene of H. pylori is shown to be related to NO resistance, as its inactivation increases the susceptibility of H. pylori to nitrosative stress, and significantly decreases the NADPH-dependent NO reduction activity of H. pylori cells. The recombinant HP0013 protein is able to complement an NO reductase-deficient Escherichia coli strain and exhibits significant NO reductase activity. Mutation of hp0013 renders H. pylori more vulnerable to nitric oxide synthase-dependent macrophage killing, and decreases the ability of the pathogen to colonize mice stomachs.
Phylogenetic studies reveal that HP0013, which shares no significant amino acid sequence similarity to the other so far known microbial NO detoxifiers, belongs to a novel family of proteins with a widespread distribution in the microbial world.
H. pylori HP0013 represents an unprecedented enzymatic NO detoxifying system for the in vivo microbial protection against nitrosative stress.
病原体需要应对存在于某些宿主小生境中和支持先天免疫的吞噬细胞产生的一氧化氮（NO）的破坏作用，这依赖于多种策略，包括解毒酶的作用。对于许多其他病原体来说，这些系统对于幽门螺杆菌来说仍然未知。这项工作旨在鉴定和功能表征与 NO 保护相关的幽门螺杆菌系统。
本工作表明，幽门螺杆菌的 hp0013 基因与 NO 抗性有关，因为其失活会增加幽门螺杆菌对硝化应激的敏感性，并显著降低幽门螺杆菌细胞中 NADPH 依赖性 NO 还原活性。重组 HP0013 蛋白能够补充缺乏一氧化氮还原酶的大肠杆菌菌株，并表现出显著的一氧化氮还原酶活性。hp0013 的突变使幽门螺杆菌更容易受到一氧化氮合酶依赖性巨噬细胞杀伤，并降低了病原体在小鼠胃中定植的能力。
系统发育研究表明，HP0013 与迄今为止已知的其他微生物 NO 解毒剂没有显著的氨基酸序列相似性，属于一个在微生物世界中广泛分布的新型蛋白质家族。
幽门螺杆菌 HP0013 代表了一种前所未有的酶促 NO 解毒系统，用于体内微生物对硝化应激的保护。
