Binder S, Thalheim C, Brennicke A
Institut für Genbiologische Forschung, Berlin, Germany.
Curr Genet. 1994 Nov-Dec;26(5-6):519-23. doi: 10.1007/BF00309943.
Transcription initiation sites in plant mitochondria can be located by in vitro capping of primary 5' transcript termini. Direct sequencing of a cap-labelled mitochondrial RNA from potato shows its sequence to be identical to the 5' terminal part of the 26S rRNA. Primer extension analysis indicates the mature 5' end to be the sole detectable 5' transcript terminus. In potato mitochondria the mature 5' end of the 26S rRNA is thus created by transcription initiation without any further 5' processing. The nucleotide sequence surrounding this transcription initiation site shows only limited similarity to other putative promoter sequences from dicot plant mitochondria suggesting the possibility that divergent RNA polymerases, and/or transcription initiation factors, are present in plant mitochondria.
植物线粒体中的转录起始位点可通过对初级5'转录本末端进行体外加帽来定位。对来自马铃薯的帽标记线粒体RNA进行直接测序，结果显示其序列与26S rRNA的5'末端部分相同。引物延伸分析表明，成熟的5'末端是唯一可检测到的5'转录本末端。因此，在马铃薯线粒体中，26S rRNA的成熟5'末端是通过转录起始产生的，无需任何进一步的5'加工。该转录起始位点周围的核苷酸序列与双子叶植物线粒体的其他推定启动子序列仅显示出有限的相似性，这表明植物线粒体中可能存在不同的RNA聚合酶和/或转录起始因子。
