科学家揭示艾滋病毒外壳完整结构
文章来源:未知 文章作者:enread 发布时间:2011-01-20 02:00 字体: [ ]  进入论坛
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A team of scientists at The Scripps Research Institute and the University of Virginia has determined1 the structure of the protein package that delivers the genetic2 material of the human immunodeficiency virus (HIV) to human cells. The work is the culmination3(顶点,高潮) of studies carried out over the last decade looking at different portions of the cone4-shaped container, or the capsid(衣壳) . The final piece of the puzzle, described in an article published in Nature on January 20, 2011, details the structure of the two ends of the cone(圆锥体) .

"This paper is a real milestone5 for research from our group," says the study's senior author Mark Yeager, M.D., Ph.D., a Scripps Research professor and staff cardiologist(心脏病学家) and chair of the Molecular6 Physiology7 and Biological Physics Department at The University of Virginia School of Medicine.

A detailed8 description of the complete HIV capsid will provide a roadmap for developing drugs that can disrupt its formation and thus prevent infection by HIV.

Assembling the Package

HIV binds9 to receptors on human cells and then delivers the capsid inside them. Once inside a cell, the capsid comes apart, releasing its precious cargo—the virus's genetic material.

HIV then sabotages10(妨害,破坏) the cell machinery11 to make many copies of its genes12 and proteins. As new viruses are made, the genetic material is packaged into spherical13(球形的) immature14 capsids that HIV uses to escape from the infected cell. But before these newly released viruses can infect other cells, the immature capsid undergoes a dramatic rearrangement to form the mature, cone-shaped shell.

If formation of the mature capsid is disrupted, the virus is no longer infectious. Thus, new drugs targeting capsid formation could provide valuable additions to the arsenal15 of existing drugs against HIV.

A "Floppy16" Bridge

To develop drugs that disrupt capsid formation, however, scientists first need to know precisely17 how it is formed.

One technology researchers use to obtain detailed structures of biological molecules19 is X-ray crystallography(结晶学) . This technique requires growing crystals of a molecule18 and then bombarding the crystals with X-rays to determine the positions of all the atoms.

But unlike the cone-shaped capsids of other viruses, such as the poliovirus(小儿麻痹病毒) , which have a rigid20, symmetrical structure that obediently(顺从地) assembles into crystals, the HIV capsid is flexible and can adopt slightly different shapes.

Part of the reason for this flexibility21 is the protein that makes up the HIV capsid, the CA protein, consists of two ends held together by a "floppy" bridge.

In the capsid, each CA protein joins hands with other CA proteins, forming groups of five or six proteins. The main body of the capsid contains about 250 of the six-fold units or hexamers(六聚物) . Each end of the cone is then closed off by either five or seven smaller five-fold units or pentamers(五节聚化物) .

"It is impossible to grow crystals of the entire HIV capsid," says Yeager. As a result, his team used a "divide and conquer approach."

Divide and Conquer

Working with husband-and-wife team Owen Pornillos and Barbie Ganser-Pornillos, investigators22 in his lab, Yeager partitioned(划分,分隔) the HIV capsid into smaller components23, then determined their respective structures.

Yeager's group started by focusing on the structure of the CA hexamer. A breakthrough came in a 2007, when the group viewed the CA hexamers with a powerful electron microscope. Guided by information from that structure, in 2009 the team managed to trick the CA hexamers into forming crystals. The researchers were then able to determine the particles' structures at 2-Angstrom resolution (one Angstrom equals one ten-billionth of a meter).

Having cracked the atomic structure of the hexamer, the investigators turned their attention to the more elusive24 pentamers.



点击收听单词发音收听单词发音  

1 determined duszmP     
adj.坚定的;有决心的
参考例句:
  • I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
  • He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
2 genetic PgIxp     
adj.遗传的,遗传学的
参考例句:
  • It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
3 culmination 9ycxq     
n.顶点;最高潮
参考例句:
  • The space race reached its culmination in the first moon walk.太空竞争以第一次在月球行走而达到顶峰。
  • It may truly be regarded as the culmination of classical Greek geometry.这确实可以看成是古典希腊几何的登峰造级之作。
4 cone lYJyi     
n.圆锥体,圆锥形东西,球果
参考例句:
  • Saw-dust piled up in a great cone.锯屑堆积如山。
  • The police have sectioned off part of the road with traffic cone.警察用锥形路标把部分路面分隔开来。
5 milestone c78zM     
n.里程碑;划时代的事件
参考例句:
  • The film proved to be a milestone in the history of cinema.事实证明这部影片是电影史上的一个里程碑。
  • I think this is a very important milestone in the relations between our two countries.我认为这是我们两国关系中一个十分重要的里程碑。
6 molecular mE9xh     
adj.分子的;克分子的
参考例句:
  • The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
7 physiology uAfyL     
n.生理学,生理机能
参考例句:
  • He bought a book about physiology.他买了一本生理学方面的书。
  • He was awarded the Nobel Prize for achievements in physiology.他因生理学方面的建树而被授予诺贝尔奖。
8 detailed xuNzms     
adj.详细的,详尽的,极注意细节的,完全的
参考例句:
  • He had made a detailed study of the terrain.他对地形作了缜密的研究。
  • A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
9 binds c1d4f6440575ef07da0adc7e8adbb66c     
v.约束( bind的第三人称单数 );装订;捆绑;(用长布条)缠绕
参考例句:
  • Frost binds the soil. 霜使土壤凝结。 来自《简明英汉词典》
  • Stones and cement binds strongly. 石头和水泥凝固得很牢。 来自《简明英汉词典》
10 sabotages ae85dff2475bd665b37babb1e4bd42d3     
阴谋破坏(某事物)( sabotage的第三人称单数 )
参考例句:
  • The plastic sheeting used in farmland extremely pollutes and sabotages the soil environment. 农田塑料薄膜(地膜)污染对土壤环境危害很大,覆膜灌溉技术可能会增加其复杂性。
11 machinery CAdxb     
n.(总称)机械,机器;机构
参考例句:
  • Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗?
  • Machinery ought to be well maintained all the time.机器应该随时注意维护。
12 genes 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
13 spherical 7FqzQ     
adj.球形的;球面的
参考例句:
  • The Earth is a nearly spherical planet.地球是一个近似球体的行星。
  • Many engineers shy away from spherical projection methods.许多工程师对球面投影法有畏难情绪。
14 immature Saaxj     
adj.未成熟的,发育未全的,未充分发展的
参考例句:
  • Tony seemed very shallow and immature.托尼看起来好像很肤浅,不夠成熟。
  • The birds were in immature plumage.这些鸟儿羽翅未全。
15 arsenal qNPyF     
n.兵工厂,军械库
参考例句:
  • Even the workers at the arsenal have got a secret organization.兵工厂工人暗中也有组织。
  • We must be the great arsenal of democracy.我们必须成为民主的大军火库。
16 floppy xjGx1     
adj.松软的,衰弱的
参考例句:
  • She was wearing a big floppy hat.她戴了顶松软的大帽子。
  • Can you copy those files onto this floppy disk?你能把那些文件复制到这张软盘上吗?
17 precisely zlWzUb     
adv.恰好,正好,精确地,细致地
参考例句:
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
18 molecule Y6Tzn     
n.分子,克分子
参考例句:
  • A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈?f婘??妈?成的。
  • This gives us the structural formula of the molecule.这种方式给出了分子的结构式。
19 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
20 rigid jDPyf     
adj.严格的,死板的;刚硬的,僵硬的
参考例句:
  • She became as rigid as adamant.她变得如顽石般的固执。
  • The examination was so rigid that nearly all aspirants were ruled out.考试很严,几乎所有的考生都被淘汰了。
21 flexibility vjPxb     
n.柔韧性,弹性,(光的)折射性,灵活性
参考例句:
  • Her great strength lies in her flexibility.她的优势在于她灵活变通。
  • The flexibility of a man's muscles will lessen as he becomes old.人老了肌肉的柔韧性将降低。
22 investigators e970f9140785518a87fc81641b7c89f7     
n.调查者,审查者( investigator的名词复数 )
参考例句:
  • This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
  • The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》
23 components 4725dcf446a342f1473a8228e42dfa48     
(机器、设备等的)构成要素,零件,成分; 成分( component的名词复数 ); [物理化学]组分; [数学]分量; (混合物的)组成部分
参考例句:
  • the components of a machine 机器部件
  • Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。
24 elusive d8vyH     
adj.难以表达(捉摸)的;令人困惑的;逃避的
参考例句:
  • Try to catch the elusive charm of the original in translation.翻译时设法把握住原文中难以捉摸的风韵。
  • Interpol have searched all the corners of the earth for the elusive hijackers.国际刑警组织已在世界各地搜查在逃的飞机劫持者。
TAG标签: genetic cells protein HIV
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