生物谷報(bào)道：端粒酶（起穩(wěn)定線形染色體端部這一重要作用的核糖核蛋白（RNP）組合體）的生物起源是一個(gè)健康細(xì)胞中的一個(gè)重要過(guò)程,，破壞它們的突變能引起疾病,。但是,，研究人員對(duì)RNP組合體的機(jī)制很不了解,。最近，哈佛大學(xué)莊曉薇教授研究組的Michael Stone等人利用一種單分子方法對(duì)端粒酶組合體進(jìn)行了實(shí)時(shí)分析,，對(duì)每個(gè)組合步驟的精確順序進(jìn)行了分解,。他們的結(jié)果確定了一個(gè)分成不同層次的組合機(jī)制，該機(jī)制包含兩個(gè)連續(xù)的步驟—由蛋白誘導(dǎo)的RNA折疊,，最后是將端粒酶復(fù)合物模制成它的功能形狀,。研究結(jié)果發(fā)表在最新一期的《nature》雜志上。
莊曉薇研究組研究了一種名為嗜熱四膜蟲(chóng)（Tetrahymena thermophila）的單細(xì)胞水生生物的端粒酶,，因?yàn)閱渭?xì)胞生物比更高等的生物結(jié)構(gòu)簡(jiǎn)單,，更加容易控制。
端粒酶主要依靠?jī)煞N成分來(lái)實(shí)現(xiàn)其功能：一種名為端粒酶逆轉(zhuǎn)錄酶（TERT）的蛋白酶,，另一種對(duì)TERT起到指導(dǎo)作用的一小段RNA片段,。莊解釋說(shuō)：“端粒酶只要這兩樣?xùn)|西就可以起作用，但是實(shí)際上如果你僅僅把它們簡(jiǎn)單地放到一起去,，它們是不會(huì)組裝成功能結(jié)構(gòu)的,。還需要一些其它的輔助蛋白。”莊的研究組與伯克利Kathleen Collins小組合作,，發(fā)現(xiàn)第三種分子——一種名為p65的蛋白質(zhì)促進(jìn)了端粒酶的組裝,。 莊及其合作者們利用斯坦福科學(xué)家Lubert Stryer首創(chuàng)的熒光共振能量轉(zhuǎn)移檢測(cè)系統(tǒng)（FRET），實(shí)時(shí)精確觀察到端粒酶一步步進(jìn)行組裝的全過(guò)程,。
莊曉薇說(shuō),，下一步他們將研究更高級(jí)有機(jī)體中的端粒酶，以期最終研究人類的端粒酶組裝機(jī)制,。
FIGURE 1. Telomerase proteins p65 and TERT induce distinct conformational changes in telomerase RNA
a, Full-length telomerase RNA labelled with FRET donor (Cy3) and acceptor (Cy5). RNA molecules were immobilized on a streptavidin-coated surface by a biotin molecule engineered onto an extension of stem II. The interaction sites with p65 (red) and TERT (green) are highlighted20, 24. Inset: telomerase primer extension assay with dye-labelled (L) and unlabelled (U) RNA or without RNA (-). Numbers at the right indicate the number of nucleotides added to generate each product. b, FRET histograms of RNA molecules in the absence of protein (grey bars), the presence of 10 nM p65 (red bars) or 10 nM p65 plus 32 nM TERT1–516 (green bars). A peak at FRET = 0 due to the presence of about 30% of molecules without active Cy5 (Supplementary Fig. 2) was removed from these histograms.
原文出處：
Nature Volume 446 Number 7134
Stepwise protein-mediated RNA folding directs assembly of telomerase ribonucleoprotein p458
Michael D. Stone, Mariana Mihalusova, Catherine M. O'Connor, Ramadevi Prathapam, Kathleen Collins and Xiaowei Zhuang
doi:10.1038/nature05600
First paragraph | Full Text | PDF (321K) | Supplementary information
See also: Editor's summary
作者簡(jiǎn)介：
Xiaowei Zhuang
Howard Hughes Medical Institute Investigator
Professor of Chemistry and Chemical Biology
Professor of Physics
美國(guó)哈佛大學(xué)化學(xué)與化學(xué)生物系： Xiaowei Zhuang 副教授的研究組
【URL】 http://zhuang.harvard.edu/
【研究方向】
1)Fundamental understanding of viral infection
2)Structural dynamics and function RNA and ribonucleoprotein (RNP) enzymes
3)RNA interference and micro RNAs
4)Nano-electronic devices for sensing bio-molecules and bio-pathogens at the single-unit level
【簡(jiǎn)介】
The major interest of Professor Zhuang and her group is to study complex biological processes at the single molecule (or single working unit) level. They are also interested in developing new imaging techniques to image biological molecules and cells.Understanding fundamental molecular mechanisms underlying biological processes is one of the major goals in modern biology
