Functional Redundancy of the Duplex Telomeric DNA-binding Proteins in Arabidopsis

阿拉伯芥雙股端粒結合蛋白質間有功能性重複

陳忠謀(Chung-Mong Chen) ； 王琪婷(Chi-Ting Wang) ； 高玉馨(Yu-Hsin Kao) ； 張震東(Geen-Dong Chang) ； 何佳幸(Chia-Hsing Ho) ； 李鳳鳴(Feng-Ming Lee) ； 許明智(Ming-Jhy Hseu)

《Botanical Bulletin of Academia Sinica》 46卷4期 (2005/10) Pp. 315-324

https://doi.org/10.7016/BBAS.200510.0315

摘要

AtTRP1是阿拉伯芥一個雙股端粒DNA結合蛋白質。剔除AtTRP1基因沒有造成端粒DNA長度顯著變化，顯示AtTRP1可能不參與控制端粒長度或者阿拉伯芥有多個類似AtTRP1功能的基因。分析阿拉伯芥基因組序列及利用分子選殖技術，我們找到兩個和AtTRP1高度相似的基因及cDNA選殖體，AtTRP3及AtTRP4。用細菌分別產生AtTRP3及AtTRP4蛋白質的C端片段，它們和雙股端粒DNA有專一性結合。AtTRP4的氨基酸序列中間比阿拉伯芥另一個雙股端粒DNA結合蛋白質TRFL1的氨基酸序列短缺6個氨基酸，其餘完全一樣。這意味著AtTRP4和AtTRP1是同一基因經由不同剪接方式產生。將AtTRP4和TRFL1的傳訊者RNA間差異的部分用反轉錄酵素製成。DNA，再用聚合酵素連鎖反應加以增殖，經核酸定序確認上述推論正確。我們的結果合併其他研究者的報告顯示阿拉伯芥基因組有6個基因產生7個雙股端粒DNA結合蛋白質，它們的C端都有一個高度相似的Myb DNA結合功能專區。因為剔除AtTRP1對阿拉伯芥端粒長度無影響，所以我們推論阿拉伯芥這7個雙股端粒DNA結合蛋白質中至少有部分和AtTRP1在功能上相同或重複。

關鍵字

不同基因剪接 ； 阿拉伯芥 ； 功能性重複 ； 基因剔除變異株 ； 端粒DNA結合蛋白質 ； 端粒長度

並列摘要

AtTRPl is an Arabidopsis protein that binds duplex telomeric DNA in vitro. Here we showed that knockout of AtTRPl did not change significantly the telomere length in plant. This implies that either AtTRPl does not participate in the regulation of telomere length or the Arabidopsis genome contains other genes functionally redundant to AtTRPl. Sequence analysis of Arabidopsis genome together with molecular cloning enabled us to identify two additional genes AtTRP3 and AtTRP4 and the corresponding cDNA clones encoding AtTRP1-like proteins. The C-terminal regions of both AtTRP3 and AtTRP4 proteins bind specifically duplex telomeric DNA in vitro. The amino acid sequence of AtTRP4 is identical to that of another Arabidopsis protein TRFL1 except with an internal deletion of six amino acids, suggesting that AtTRP4 and TRFL1 may be derived from the same gene by alternative splicing. This speculation was further confirmed by DNA sequence analysis of RT-PCR products specific for AtTRP4 and TRFL1 transcripts. Our data together with reports from other researchers revealed that Arabidopsis contains at least seven different duplex telomeric DNA-binding proteins encoded by a six-member gene family, named AtTRP. We proposed that some members of the AtTRP family may be functionally redundant in the regulation of telomere length in Arabidopsis.

並列關鍵字

Alternative splicing ； Arabidopsis thaliana ； Functional redundancy ； Knockout mutant ； Telomere length ； Telomeric DNA-binding protein.