Asari Masaru, Tan Yuka, Watanabe Satoshi, Shimizu Keiko, Shiono Hiroshi
Department of Legal Medicine, Asahikawa Medical College, 2-1 Midorigaokahigashi, Asahikawa 078-8510, Japan.
Biochem Biophys Res Commun. 2007 Sep 28;361(3):641-4. doi: 10.1016/j.bbrc.2007.07.055. Epub 2007 Jul 23.
In addition to stabilizing the RNA-DNA hybrid, conserved sequence block (CSB) II, which is located at nucleotides 299-315 on mitochondrial DNA, relates with the transcription termination for initiation of heavy strand synthesis in human mitochondrial replication. Due to length polymorphisms at nucleotides 303-315, individuals contain homo- or heteroplasmic profiles with length variants from C(5)TC(6) to C(15)TC(6) or from C(9) to C(13). Using in vitro transcription with templates containing these variations, we demonstrated that the production of prematurely terminated (PT) transcripts depends on the 303-315 sequences, and that longer templates result in relatively higher levels of PT transcripts. The 3' ends of PT transcripts were observed within or downstream of CSB II. Termination positions downstream of nucleotide 303 were shifted upstream by longer variations, but not shifted by shorter variations. We found that length variations between 303 and 315 generate quantitative and qualitative differences in PT transcripts.
除了稳定RNA-DNA杂交体外，位于线粒体DNA上第299-315位核苷酸的保守序列块（CSB）II与人类线粒体复制中重链合成起始的转录终止有关。由于第303-315位核苷酸存在长度多态性，个体含有同质性或异质性图谱，其长度变体从C(5)TC(6)到C(15)TC(6)或从C(9)到C(13)。使用含有这些变异的模板进行体外转录，我们证明了过早终止（PT）转录本的产生取决于303-315序列，并且较长的模板会导致相对较高水平的PT转录本。在CSB II内部或下游观察到PT转录本的3'末端。核苷酸303下游的终止位置因较长的变异而向上游移动，但不因较短的变异而移动。我们发现303和315之间的长度变异会在PT转录本中产生数量和质量上的差异。
