Hexose Oxidase-Mediated Hydrogen Peroxide as a Mechanism for the Antibacterial Activity in the Red Seaweed Ptilophora subcostata.
Hexose Oxidase-Mediated Hydrogen Peroxide as a Mechanism for the Antibacterial Activity in the Red Seaweed Ptilophora subcostata.
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DOI：
10.1371/journal.pone.0149084
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Nishimura M
中科院分区：
文献类型：
--
作者：
Ogasawara K;Yamada K;Hatsugai N;Imada C;Nishimura M
海藻对微生物感染有独特的防御策略。然而，它们的免疫机制尚不清楚，对海藻和陆生高等植物免疫系统的相似性也知之甚少。在这里，我们提出了藻类免疫的一个可能机制，涉及依赖己糖氧化酶(HOX)产生过氧化氢(H2O2)。我们检查了五种不同红藻的粗提物，以了解它们防止细菌生长的能力。其中一种藻类Ptilophora subcostata的提取物特别有活性，可以防止革兰氏阳性和阴性细菌的生长，而过氧化氢酶可以完全抑制这种细菌的生长。这种提取物对酵母或丝状真菌的生长都没有影响。我们部分纯化了与其抗菌活性有关的一种酶，该酶与红藻Chondrus crispus的HOX有50%的同源性。凝胶内碳水化合物氧化酶分析表明，副肋骨侧耳提取物具有依赖己糖的方式产生H_2O_2的能力，并且在半乳糖存在的情况下这种能力最高。此外，在GYP琼脂平板上，枯草芽孢杆菌在枯草芽孢杆菌附近的生长受到强烈抑制。这些结果表明，Hox通过调节海洋环境中H_2O_2的产生，在副肋骨条藻对细菌攻击的抗性中发挥作用。
Marine algae have unique defense strategies against microbial infection. However, their mechanisms of immunity remain to be elucidated and little is known about the similarity of the immune systems of marine algae and terrestrial higher plants. Here, we suggest a possible mechanism underlying algal immunity, which involves hexose oxidase (HOX)-dependent production of hydrogen peroxide (H2O2). We examined crude extracts from five different red algal species for their ability to prevent bacterial growth. The extract from one of these algae, Ptilophora subcostata, was particularly active and prevented the growth of gram-positive and -negative bacteria, which was completely inhibited by treatment with catalase. The extract did not affect the growth of either a yeast or a filamentous fungus. We partially purified from P. subcostata an enzyme involved in its antibacterial activity, which shared 50% homology with the HOX of red seaweed Chondrus crispus. In-gel carbohydrate oxidase assays revealed that P. subcostata extract had the ability to produce H2O2 in a hexose-dependent manner and this activity was highest in the presence of galactose. In addition, Bacillus subtilis growth was strongly suppressed near P. subcostata algal fronds on GYP agar plates. These results suggest that HOX plays a role in P. subcostata resistance to bacterial attack by mediating H2O2 production in the marine environment.