Hinkle G, Leipe D D, Nerad T A, Sogin M L
Center for Molecular Evolution, Marine Biological Laboratory, Woods Hole, MA 02543.
Nucleic Acids Res. 1994 Feb 11;22(3):465-9. doi: 10.1093/nar/22.3.465.
The small subunit ribosomal RNA (rRNA) of the anaerobic amoeba Phreatamoeba balamuthi is the longest 16S-like rRNA sequenced to date. Secondary structure analysis suggests that the additional sequence is incorporated in canonical eukaryotic expansion regions and is not due to the presence of introns. Reverse transcriptase sequencing of total RNA extracts confirmed that two uncommonly long expansion regions are present in native P. balamuthi 16S-like rRNA. Primary sequence comparison and similar secondary structure indicate a 61 base stem and loop repeat within an expansion region; a mechanism whereby the repeat may have been incorporated is presented. P. balamuthi provides further evidence that 16S-like rRNA length does not correlate with phylogenetic position.
厌氧变形虫巴拉姆希嗜热变形虫的小亚基核糖体RNA(rRNA)是迄今为止测序的最长的16S样rRNA。二级结构分析表明,额外的序列被纳入了典型的真核生物扩展区域,并非由于内含子的存在。对总RNA提取物进行逆转录酶测序证实,天然的巴拉姆希嗜热变形虫16S样rRNA中存在两个异常长的扩展区域。一级序列比较和相似的二级结构表明,在一个扩展区域内有一个61个碱基的茎环重复序列;提出了一种该重复序列可能被纳入的机制。巴拉姆希嗜热变形虫进一步证明,16S样rRNA的长度与系统发育位置无关。