Sýkorová Eva, Leitch Andrew Rowland, Fajkus Jirí
Laboratory of DNA-Molecular Complexes, Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, Brno, CZ-61265, Czech Republic.
Plant Mol Biol. 2006 Mar;60(5):633-46. doi: 10.1007/s11103-005-5091-9.
The order of monocotyledonous plants Asparagales is attractive for studies of telomere evolution as it includes three phylogenetically distinct groups with telomeres composed of TTTAGGG (Arabidopsis-type), TTAGGG (human-type) and unknown alternative sequences, respectively. To analyze the molecular causes of these switches in telomere sequence (synthesis), genes coding for the catalytic telomerase subunit (TERT) of representative species in the first two groups have been cloned. Multiple alignments of the sequences, together with other TERT sequences in databases, suggested candidate amino acid substitutions grouped in the Asparagales TERT synthesizing the human-type repeat that could have contributed to the changed telomere sequence. Among these, mutations in the C motif are of special interest due to its functional importance in TERT. Furthermore, two different modes of initial elongation of the substrate primer were observed in Asparagales telomerases producing human-like repeats, which could be attributed to interactions between the telomerase RNA subunit (TR) and the substrate.
单子叶植物天门冬目对于端粒进化研究具有吸引力，因为它包含三个系统发育上不同的类群，其端粒分别由TTTAGGG（拟南芥型）、TTAGGG（人类型）和未知的替代序列组成。为了分析这些端粒序列（合成）转换的分子原因，已经克隆了前两组代表性物种的催化端粒酶亚基（TERT）编码基因。这些序列与数据库中的其他TERT序列的多重比对表明，在合成人类型重复序列的天门冬目TERT中，候选氨基酸替换可能导致了端粒序列的改变。其中，C基序中的突变因其在TERT中的功能重要性而特别受关注。此外，在产生类人重复序列的天门冬目端粒酶中观察到了底物引物初始延伸的两种不同模式，这可能归因于端粒酶RNA亚基（TR）与底物之间的相互作用。
