Yamazaki Syuji, Kikuchi Hisashi, Kawarabayasi Yutaka
National Institute of Technology and Evaluation, Nishihara, Shibuya, Tokyo, Japan.
DNA Res. 2005;12(6):403-16. doi: 10.1093/dnares/dsi023. Epub 2006 Feb 23.
The tRNA molecule has an important role in translation, the function of which is to carry amino acids to the ribosomes. It is known that tRNA is transcribed from tRNA genes, some of which, in Eukarya and Archaea, contain introns. A computational analysis of the complete genome of Aeropyrum pernix K1 predicted the presence of 14 intron-containing tRNA genes. To elucidate whether these introns are actually processed in living cells and what mechanism detects the intron regions, cDNAs for premature and mature forms of the tRNA molecules transcribed from the intron-containing tRNA genes in the model aerobic acidothermophilic crenarchaeon, A. pernix K1 were identified and analyzed. A comparison between the nucleotide sequences of these two types of cDNAs indicated that the intron regions of the tRNA molecules were indeed processed in A. pernix K1 living cells. Some cDNA clones showed that the actual splicing positions were different from those predicted by computational analysis. However, the bulge-helix-bulge structure, which has been previously identified in exon-intron boundaries of archaeal tRNA genes, was evident in all boundary regions confirmed in this work. These results indicate that the generally described mechanism for tRNA processing in Archaea is utilized for processing the intron region of the tRNA molecules in A. pernix K1.
转运RNA（tRNA）分子在翻译过程中发挥着重要作用，其功能是将氨基酸转运至核糖体。已知tRNA由tRNA基因转录而来，在真核生物和古生菌中，其中一些tRNA基因含有内含子。对嗜热栖热菌（Aeropyrum pernix K1）全基因组的计算分析预测存在14个含内含子的tRNA基因。为阐明这些内含子在活细胞中是否真的被加工以及何种机制能检测到内含子区域，对模式需氧嗜酸泉古菌嗜热栖热菌K1中含内含子的tRNA基因转录的tRNA分子的前体和成熟形式的cDNA进行了鉴定和分析。这两种cDNA核苷酸序列的比较表明，tRNA分子的内含子区域在嗜热栖热菌K1活细胞中确实被加工。一些cDNA克隆显示实际剪接位置与计算分析预测的不同。然而，先前在古菌tRNA基因外显子 - 内含子边界中鉴定出的凸起 - 螺旋 - 凸起结构在本研究确认的所有边界区域都很明显。这些结果表明，古菌中普遍描述的tRNA加工机制被用于加工嗜热栖热菌K1中tRNA分子的内含子区域。
