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標題: | 紫外線照射下水稻白葉枯病原菌之蛋白質磷酸化及核醣核酸合成活性的改變 Alteration of Protein Phosphorylation and Activity of RNA Synthesis Induced by UV-Irradiation in Xanthomonas oryzae pv. oryzae |
作者: | 林珊華 |
出版年 : | 1995 |
學位: | 碩士 |
摘要: | 本論文研究水稻白葉枯病原菌(Xanthomonas oryzae pv. oryzae)生體外磷酸化標定(In vitro phosphorylation labelling)的三種主要磷酸蛋白,p32、p44與p81經UV照射後,其磷酸化程度改變情形,與生體外核醣核酸合成反應活性之變化。 隨著菌體生長,在不同的時期這些磷酸化蛋白會有不同表現,p32及p81均為組織氨酸(histidine)磷酸化蛋白,隨著生長時間增長,其磷酸化程度降低;相反地,p44主要為絲氨酸(serine)磷酸化與少量組織氨酸磷酸化蛋白,隨著生長時間增長,p44之磷酸化程度會增加。 紫外線照射後,會立即抑制菌體之DNA合成速率與生長,而在磷酸化蛋白之調節上,會造成組氨酸磷酸化蛋白p32及p81的磷酸化程度快速地降低,而另一方面,p44磷酸蛋白經紫外線照射後的變化情形則是隨著菌體之生長時期不同而有差異;此外,以mitomycin C、actinomycin D及ethidium bromide等DNA傷害劑(DNA damaging agents)處理,也觀察到相同的現象。如果以轉錄抑制劑rifampicin與轉譯抑制劑chloramphenicol處理菌體時,發現抑制轉錄會造成組織氨酸磷酸化蛋白p32及p81磷酸化程度降低,並抑制菌體DNA合成速率與生長;而抑制轉譯時,p32及p81磷酸化程度只有些微的降低,而且菌體的DNA合成速率較慢,但仍能完全地抑制菌體的生長。 此外,在對數期早期菌液經低劑量紫外線照射後,利用生體外轉錄方式觀察到核醣核酸聚合?活性增加,這種活性之改變不需新合成蛋白質參與,並發現有新的核醣核酸聚合?結合蛋白質,推測此經紫外線照射所誘發之現象可能和菌體紫外線照射後,細胞需大量表現紫外線誘發基因以應付危機有關。 由上述結果推論,組織氨酸磷酸化蛋白質其磷酸化程度的降低,並非組織氨酸磷酸化蛋白質的轉錄受抑制,或菌體生長受抑制的影響,而是伴隨著DNA合成速率降低所出現。 The investigation on the alteration of protein phosphorylation on three major phosphoproteins: p81, p44 and p32, and the activity of RNA synthesis after UV-irradiation in Xanthomonas oryzae pv. oryzae. The expression of these phosphoproteins are growth-phase dependent. The p81 and p31 were phosphorylated on histidine, their intansity decreased with growth phase. The p44, phosphorylated mainly on serine and some on histidine, increased with the culture time. After UV-irradiation, the phosphorylation level of phosphor-histidine containing protein, p32 and p81, decreased. The rate of DNA synthesis was inhibited by UV-irradiation. The phosphorylation state of p44 was growth phase dependent, that could be changed after UV-irradiation. DNA damaging agents, including mitomycin C, actinomycin D and ethidium bromide induced similar alteration as UV-irradiation did. The treatment with rifampicin, a transcriptional inhibitor, decresed the phosphorylation level of p81 and p31, but not p44. Treat with chloramphenicol did not cause such alteration. As the rate of DNA synthesis in X.o.o. would be inhibited by rifampin treatment, but not by chloramphenicol. Moreover by in vitro RNA synthesis assay, the RNA polymerase extracted from bacteria of early exponentional stage increased after low doses UV-irradiation. The increase waa not supressed by inhibiting the translation. The increase may be related to the UV induced gene expression. These results suggest the decrese of phosphorylation level in phospho-histidine containing protein is not caused by inhibition of translation, and its occured in accompany with the inhibition of DNA synthesis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76135 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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