Iwashita Chikako, Hori Hiroyuki
Graduate School of Materials and Biotechnology, Ehime University, Matsuyama 790-8577, Japan.
Nucleic Acids Symp Ser (Oxf). 2006(50):247-8. doi: 10.1093/nass/nrl123.
Thermus thermophilus HB8 is an extreme thermophilic eubacrium, which grows at 50-80 degrees C. Transfer RNA molecules in T. thermophilus HB8 contains modified nucleosides such as Gm18, m(7)G46, m(5)s(2)U54, Psi55, and m(1)A58. Recently, all responsible genes for these modifications have been identified. To clarify the relationship of the amounts of the RNA modification enzymes (proteins) and culture conditions, we investigated the activities and quantities of the proteins. In this meeting, we report the amount changes of tRNA (Gm18) methyltransferase [TrmH] in T. thermophilus HB8 cells cultured at 52, 67, 75, and 79 degrees C. 60 mug of total proteins in the crude extract from cells cultured at 67 degrees C contained about 10-30 ng of the TrmH protein. Thus, the content of the TrmH protein was estimated to be around 1/5000 of the total proteins. Through the log phase, the content of the TrmH protein was not changed obviously. However, in the stationary phase, the content of the TrmH protein was slowly reduced. The TrmH contents in the cells cultured at 75 or 79 degrees C were similar to that at 67 degrees C. However, the content of the TrmH protein in the extract from 52 degrees C cultured cells slightly decreased as compared with that in the 67 degrees C cultured cells.
嗜热栖热菌HB8是一种极端嗜热真细菌，能在50 - 80摄氏度下生长。嗜热栖热菌HB8中的转运RNA分子含有修饰核苷，如Gm18、m(7)G46、m(5)s(2)U54、Psi55和m(1)A58。最近，已鉴定出所有负责这些修饰的基因。为了阐明RNA修饰酶（蛋白质）的量与培养条件之间的关系，我们研究了这些蛋白质的活性和数量。在本次会议中，我们报告了在52、67、75和79摄氏度下培养的嗜热栖热菌HB8细胞中tRNA（Gm18）甲基转移酶[TrmH]的量的变化。在67摄氏度下培养的细胞粗提物中的60微克总蛋白含有约10 - 30纳克的TrmH蛋白。因此，TrmH蛋白的含量估计约为总蛋白的1/5000。在对数生长期，TrmH蛋白的含量没有明显变化。然而，在稳定期，TrmH蛋白的含量缓慢降低。在75或79摄氏度下培养的细胞中的TrmH含量与在67摄氏度下培养的细胞中的相似。然而，与在67摄氏度下培养的细胞相比，在52摄氏度下培养的细胞提取物中TrmH蛋白的含量略有下降。
