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PNAS:一氧化氮可增加微生物耐辐射性

来源:EurekAlert! 2009-10-22 18:31

一氧化氮很可能是耐辐射奇球菌(Deinococcus Radiodurans)具有耐受能杀死更大生物的辐射剂量的能力的关键原因。这种坚韧的原核生物被用于修复放射性废料地点,而一些耐辐射奇球菌在罐头食品产品中被发现。这种生物被称为“世界上最坚韧的”细菌,这是由于它能耐受极端温度、严重脱水以及致命剂量的辐射。

Brian Crane及其同事研究了这种细菌的辐射生存能力,结果发现了接触紫外线能增强它的一氧化氮合酶的产量,这种酶负责制造一氧化氮。在动物中,一氧化氮被证明在一系列的生物过程中扮演了一个角色,包括防止病原体,调控血管张力、激素释放以及神经元信号传导。这组作者使用了一种遗传改造过的耐辐射奇球菌,它的一氧化氮合酶被去除了。结果他们发现,尽管这种生物能耐受其他应激物(包括接触自由基),它们在接触辐射之后的生存不良。(生物谷Bioon.com)

生物谷推荐原始出处:

PNAS October 19, 2009, doi: 10.1073/pnas.0907262106

Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium Deinococcus radiodurans from exposure to UV light

Bhumit A. Patela, Magali Moreaua, Joanne Widoma, Huan Chenb, Longfei Yinb, Yuejin Huab and Brian R. Cranea,1

aDepartment of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and
bInstitute of Nuclear-Agricultural Sciences, Zhejiang University, Hangzhou 310008, China

Deinococcus radiodurans (Dr) withstands desiccation, reactive oxygen species, and doses of radiation that would be lethal to most organisms. Deletion of a gene encoding a homolog of mammalian nitric oxide synthase (NOS) severely compromises the recovery of Dr from ultraviolet (UV) radiation damage. The Δnos defect can be complemented with recombinant NOS, rescued by exogenous nitric oxide (NO) and mimicked in the wild-type strain with an NO scavenging compound. UV radiation induces both upregulation of the nos gene and cellular NO production on similar time scales. Growth recovery does not depend on NO being present during UV irradiation, but rather can be manifested by NO addition hours after exposure. Surprisingly, nos deletion does not increase sensitivity to oxidative damage, and hydrogen peroxide does not induce nos expression. However, NOS-derived NO upregulates transcription of obgE, a gene involved in bacterial growth proliferation and stress response. Overexpression of the ObgE GTPase in the Δnos background substantially alleviates the growth defect after radiation damage. Thus, NO acts as a signal for the transcriptional regulation of growth in D. radiodurans.

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