文献类型： 外文期刊

作者： Bai, Cheng ¹ ; Liu, Liping ¹ ; Wood, Bruce W. ² ;

作者机构： 1.Chinese Acad Trop Agr Sci, Lab Pests Comprehens Governance Trop Crop,Minist, Hainan Lab Monitoring & Control Trop Agr Pests,En, Hainan Engn Res Ctr Biol Control Trop Crops Dis &, Haikou 571101, Hainan, Peoples R China

2.ARS, USDA, Southeast Fruit & Tree Nut Res Lab, Byron, GA 31008 USA

关键词： Urea;Pecan;Xylem sap;Ribonuclease;Nickel;Nitrogen cycling

期刊名称：BMC PLANT BIOLOGY （ 影响因子：4.215； 五年影响因子：4.96 ）

ISSN： 1471-2229

年卷期： 2013 年 13 卷

页码：

收录情况： SCI

摘要： Background: Nickel (Ni) is an essential micronutrient; however, its metabolic or physiological functions in plants and animals are largely uncharacterized. The ribonucleases (RNase, e. g., RNase A) are a large family of hydrolases found in one form or many forms facilitating nitrogen (N) cycling. It is currently unknown how either a deficiency or excess of Ni influences the functionality of ribonucleases, like RNase A. This is especially true for perennial crops possessing relatively high Ni requirements. Results: We report that the 'rising' xylem sap of pecan [Carya illinoinensis (Wangenh.) K. Koch, a long-lived tree] at bud break contains a 14 kDa RNase A (aka, RNase 1), which amount has a 33% greater in Ni-deficient as in Ni-sufficient trees when exposed to Ni ions exhibits ureolytic activity. The homologous 13.4 kDa bovine pancreatic RNase A likewise exhibits ureolytic activity upon exposure to Ni ions. Ni therefore affects enzymatic function of a typically non-metalloenzyme, such as it transforms to an enzyme capable of hydrolyzing a linear amide; thus, converting an endonuclease esterase into a urease. Conclusions: We conclude that Ni potentially affects the level and activity of RNase A present in the spring xylem sap of pecan trees, and probably in other crops, it has the same influence. The catalytic property of RNase A appears to shift from a nuclease to a urease relying on Ni exposure. This is suggestive that RNase A might possess novel metabolic functionality regarding N-metabolism in perennial plants. The ability of Ni to convert the activity of plant and animal RNase A from that of a ribonuclease to a urease indicates a possible unrecognized beneficial metabolic function of Ni in organisms, while also identifying a potential detrimental effect of excessive Ni on N related metabolic activity if there is sufficient disruption of Ni homeostasis.