Analysis of a novel protein conjugation system relating to ubiquitin-like protein RURM1 of rice

活性转座子mPING在水稻突变系IM294中的转座活性明显高于原始品种金波津。由于IM294被认为在Rurm1位点存在隐性突变等位基因，因此正常Rurm1基因的破坏很可能参与了IM294的高mPING转座活性。本研究通过对Rurm1基因功能缺失引起的突变进行分析，以阐明与RURM1蛋白相关的一个新的水稻蛋白结合系统(Rurm1系统)，从而阐明mPING转座的诱导机制。本研究首先利用转座子显示的方法分析了Rurm1功能缺失对mPING转座频率的影响。因此，在不同的遗传背景下证实了mPING的高频转座与Rum/功能缺失的关系，并认为Rurm1的功能缺失是mPING转座频率升高的原因之一。此外，我们还成功地建立了利用细菌重组蛋白表达系统纯化RURM1蛋白的体系，包括对产生可溶性非变性RURM1蛋白的培养条件进行了检测。用纯化的重组RURM1蛋白获得抗RURM1抗体，所提供的抗RURM1抗体证实了对RURM1蛋白的特异性识别。该抗RURM1抗体可用于鉴定参与RURM1蛋白结合系统的蛋白质。此外，本研究还鉴定了水稻的雷帕霉素靶标基因TOR，并对其进行了表达分析。由此发现，RURM1蛋白的蛋白结合系统(糖基化)可能在水稻细胞分裂调控机制中发挥重要作用。

Transposable activity of an active-transposon mPing in a rice mutant line, IM294 is much higher than in the original variety Gimbozu. Because IM294 is considered harboring a recessive mutation allele at Rurm1 locus, it is very likely that the destruction of the normal Rurm1 gene participates in high mPing transposable activity of IM294. We analyzed a change to occur by function loss of the Rurm1 gene to elucidate a novel rice protein conjugation system relating to the RURM1 protein (Rurm1 system), and this study was going to get the due to clarify the induction mechanism for the transposition of mPing.At first in this study, we analyzed the influence that the function loss of Rurm1 gave transposition frequency of mPing using the transposon display method. As a result, high-frequency transposition of mPing relation to the function loss of Rum/ was confirmed in a various genetic background, and it was suggested that the function loss of Rurm1 was one of the causes to raise transposition frequency of mPing (preparing for submission). In addition, we successfully established the system to purifying RURM1 protein with bacterial recombinant protein expression system including detection of a culture condition to produce soluble non-denaturation RURM1 protein. Anti-RURM1 antibody was obtained with the purified recombinant RURM1 protein and the provided anti-RURM1 antibody confirmed specific recognition for RURM1 protein This anti-RURM1 antibody would be useful to identify proteins, which participate in a RURM1 protein conjugation system. Furthermore, in this study, a TOR (target of rapamycin) gene of the rice was identified and an expression analysis was performed. Then, it was found possibility that the protein conjugation system for RURM1 protein (urmylation) bears an essential role in the mechanism for controlling cell division in rice plant.