机构地区: 中山大学生命科学学院基因工程教育部重点实验室
出 处: 《中山大学学报(自然科学版)》 2003年第2期62-65,共4页
摘 要: 应用不同浓度的dNTP逆转录反应,分析了苦瓜、丝瓜、蓖麻和水稻的25S rRNA sarcin/ricin区域中的甲基化核苷,发现了这4种植物25S rRNA的第3 023、2 966和2 962位的腺嘌呤、胸腺嘧啶和腺嘌呤是2’-O-甲基化核苷;在丝瓜和苦瓜25S rRNA的第2 992、2 990位的胞嘧啶和鸟嘌呤是葫芦科植物所特有的两个2’-O-甲基化核苷;第2 944位点的尿嘧啶是苦瓜、丝瓜、蓖麻和水稻的一个碱基甲基化核苷;而且,植物25S rRNA第3 023位甲基化腺嘌呤核苷刚好位于sarcin/ricin结构域的茎环上,与核糖体失活蛋白切割位点相距仅5个核苷酸,而在哺乳动物和酵母的rRNA相同位点上没有甲基化修饰的存在,根据这一结果推测,RIPs来源植物核糖体RNA的自我保护可能与这一位点的修饰有关。 Using primer extension at different dNTP concentrations the methylated nucleotides in sarcin/ricin domains and its flanked sequences of 25S rRNA were analyzed and determined from Oryza sativa, Momordica charantia, Luffa cylindrica and Ricinus communis. A3023, U2966 and A2962 were 2'-O-ribose methylated nucleotides and U2944 was base methylation modification in 25S rRNA of those four plants. C2992 and G2990 were two sites of 2'-O-ribose methylation only found in Momordica charantia and Luffa cylindrica. Interestingly, A3023 was located at sarcin/ricin loop of plant 25S rRNA. However, the site was 5 nucleotides down stream from a-sarcin/ricin cleavage site and unmethylated in mammals and S. cerevisiae rRNAs. The results suggest that the methylation modification in sarcin/ricin loop of plant rRNAs prevent the recognition and hydrolysis from the ribosome inactivating proteins.
关 键 词: 植物核糖体 植物 结构域 甲基化核苷 腺嘌呤 胸腺嘧啶
领 域: [生物学]