據(jù)physorg網(wǎng)站2006年9月13日報道,，活細胞中各種各樣的蛋白質(zhì)擔負著細胞大部分的工作,。基因中的脫氧核糖核酸（DNA）序列發(fā)布制造這些蛋白質(zhì)的指令,。各種活體生物細胞中的核糖體和微型蛋白質(zhì)加工廠分別負責從事讀取基因指令和合成特定蛋白質(zhì)的關(guān)鍵性工作,。
哈利.洛勒爾是加州大學(xué)圣塔克魯斯分校的一名分子生物學(xué)教授。他從事核糖體研究已經(jīng)30多年,。他研究的主要目標就是解開核糖體是如何工作和發(fā)展的,。許多最為有效的抗生素的對象就是細菌核糖體。洛勒爾和其它科學(xué)家取得的研究成果推動了新型抗生素的開發(fā),，這些抗生素可以殺死那些對目前使用藥物產(chǎn)生抗體的細菌,。比如抗藥性葡萄球菌感染就醫(yī)院所面臨的一個極為嚴重的問題。
洛勒爾實驗室在1999年至2001年間取得突破,，他們制作出了首個完整分子結(jié)構(gòu)的高清晰圖?，F(xiàn)在，他所領(lǐng)導(dǎo)的研究小組已經(jīng)制作出了更為高清晰的分子結(jié)構(gòu)圖,，這使他們具備制作核糖體原子模型的能力,。
新分子結(jié)構(gòu)圖為我們展示了以前從未見過的詳細細節(jié)，并為我們展現(xiàn)出蛋白質(zhì)合成過程中參與合成的確切核糖體部分,。一篇專門論述此項研究發(fā)現(xiàn)的論文將刊登在9月22日的《細胞》雜志中,，現(xiàn)在你可以在線查看該論文。
洛勒爾說,，“現(xiàn)在我們能對過去幾十年生物化學(xué)和遺傳研究的許多結(jié)論進行解答,。我們制作出的分子結(jié)構(gòu)圖將使我們?nèi)媪私夂颂求w的整個活動過程”。核糖體是由蛋白質(zhì)和核糖核酸分子組成的復(fù)雜分子機器,。洛勒爾實驗室研究的細菌（嗜熱棲熱菌）核糖體由三個不同核糖核酸分子和50個不同蛋白質(zhì)組成。
洛勒爾在二十世紀七十年代初期就提出核糖體中的核糖核酸成分擔負著核糖體的關(guān)鍵功能。在當時,，洛勒爾的這種想法被認為是“瘋子觀點”,，但是洛勒爾和其它科學(xué)家的后續(xù)研究卻證明他的觀點是正確的。
加州大學(xué)圣塔克魯斯分校核糖核酸分子生物學(xué)中心主任洛勒爾說,，“當我們首次提出此項觀點的時候,，很多人認為我們的觀點極其異端的。但是現(xiàn)在大家已經(jīng)接受這種觀點,。我們最近的研究確認核糖體中的核糖核酸在核糖體的功能發(fā)揮方面起著關(guān)鍵性作用,。蛋白質(zhì)也起著很重要的作用，但是比起核糖核酸來卻要遜色一些”,。
為了制造一個新的蛋白質(zhì),，基因中的脫氧核糖核酸序列會首先將一個遺傳指令復(fù)制成一個核糖核酸分子信息。此時核糖體從核糖核酸信息中讀取遺傳代碼,，而后將該代碼植入蛋白質(zhì)結(jié)構(gòu)當中,。
蛋白質(zhì)是一種通過折疊成復(fù)雜三維形狀來執(zhí)行其功能的線性分子。他們由氨基酸建筑塊組成,。氨基酸的排列順序決定蛋白質(zhì)的結(jié)構(gòu),。氨基酸經(jīng)核糖核酸分子轉(zhuǎn)輸進入核糖體中。在核糖體中,，核糖核酸傳輸時通過核糖核酸信息認證特定序列的遺傳代碼,，而后氨基酸以正確的序列加入其中。
洛勒爾研究小組制作的分子結(jié)構(gòu)圖不僅展示了核糖體的完整結(jié)構(gòu),，而且還展示了核糖核酸信息及兩個核糖核酸傳輸?shù)恼麄€范圍,。洛勒爾說，“我們現(xiàn)在掌握了核糖體,、核糖核酸信息和核糖核酸傳輸之間相互作用的大部分情況”,。
此項研究成果使我們對分子活動機理有了一個粗細的了解。洛勒爾將他制作的分子結(jié)構(gòu)圖與其它科研小組的分子結(jié)構(gòu)圖進行了比較,，他發(fā)現(xiàn)核糖體或者核糖體的下層結(jié)構(gòu)位置不同,。目前他正在探索分子活動中核糖體活動的線索。他說,，“我們下一步目標就是跟蹤核糖體的其它功能,，以制作出更為詳細的核糖體分子結(jié)構(gòu)圖”。
此篇論文的作者除了洛勒爾外,，還包括博士后研究員安德烈.庫洛斯德勒維,、資深科學(xué)家色爾格.特拉克哈洛維和博士后研究員馬丁.勞爾博格。研究人員使用了一種名為X射線結(jié)晶學(xué)的技術(shù),，該技術(shù)能制造出凈化核糖體晶體,，而后使用聚集X射線光束透視這些晶體,，并對產(chǎn)生的不同衍射模式進行分析。洛勒爾說,，特拉克哈洛維負責準備這些晶體,，庫洛斯德勒維和勞爾博則負責利用結(jié)晶學(xué)對晶體進行實驗，并找出核糖體的結(jié)構(gòu),。
英文原文:
Biologists probe the machinery of cellular protein factories
Harry Noller, the Sinsheimer Professor of Molecular Biology at the University of California, Santa Cruz, has been studying the ribosome for more than 30 years. His main goal is to understand how the ribosome works and how it evolved, but there are also practical reasons to pursue this research. Many of the most effective antibiotics work by targeting bacterial ribosomes, and findings by Noller and others have led to the development of novel antibiotics that hold promise for use against germs that have developed resistance to current drugs. Drug-resistant staph infections, for example, are a serious problem in hospitals.
Noller's laboratory achieved breakthroughs in 1999 and 2001, producing the first high-resolution images of the molecular structure of a complete ribosome. Now, his team has made another major advance with an even higher-resolution image that enables them to construct an atom-by-atom model of the ribosome.
The new picture shows details never seen before and suggests how certain parts of the ribosome move during protein synthesis. A paper describing the new findings will be published in the September 22 issue of the journal Cell and is currently available online.
"We can now explain a lot of the results from biochemical and genetic studies carried out over the past several decades," Noller said. "This structure gives us another frame in the movie that will eventually show us the whole process of the ribosome in action."
The ribosome is a complex molecular machine made up of proteins and RNA molecules. The bacterial ribosomes studied in Noller's lab (obtained from the bacterium Thermus thermophilus) are made up of three different RNA molecules and more than 50 different proteins.
Noller proposed in the early 1970s that the RNA component was responsible for carrying out the ribosome's key functions. At the time it was considered a "crackpot idea," but subsequent findings by Noller and others proved he was right.
"It was a completely heterodox view when we first proposed it, but it is now the accepted paradigm," said Noller, who directs the Center for Molecular Biology of RNA at UCSC. "Our latest results confirm that the ribosomal RNA is really the key to ribosome function. The proteins are also involved, but more peripherally," he said.
To make a new protein, the genetic instructions are first copied from the DNA sequence of the gene into a messenger RNA molecule. The ribosome then reads the genetic code from the messenger RNA and translates it into the structure of a protein.
Proteins are linear molecules that fold into complex three-dimensional shapes to carry out their functions. They are made from amino acid building blocks, and the sequence of amino acids determines the protein's structure. Amino acids are carried to the ribosome by transfer RNA molecules. On the ribosome, the transfer RNAs recognize specific sequences of genetic code on the messenger RNA, and the amino acids are then joined together in the proper order.
The images from Noller's group not only show the complete ribosome, they show it with a messenger RNA and two full-length transfer RNAs bound to it. "We can now see the details of most of the interactions between the ribosome, the messenger RNA, and the transfer RNAs," Noller said.
The results provide a snapshot of the molecular machine in action. By comparing his images with those obtained by other groups that have caught the ribosome or its subunits in different positions, Noller is finding clues to the molecular motions with which the ribosome does its work.
"Our next goal is to trap the ribosome in other functional states to get more frames of the movie," he said.
The authors of the paper, in addition to Noller, are postdoctoral researcher Andrei Korostelev, senior scientist Sergei Trakhanov, and postdoctoral researcher Martin Laurberg. The researchers used a technique called x-ray crystallography, which involves growing crystals of purified ribosomes, shining a focused beam of x-rays through the crystals, and analyzing the resulting diffraction pattern. Trakhanov prepared the crystals and Korostelev and Laurberg performed the crystallography and solved the structure, Noller said.
