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【bio-news】打开DNA环，“关闭”蛋白质
December 5, 2006
By Kim McDonald
It may look like mistletoe wrapped around a flexible candy cane. But this molecular model shows how some proteins form loops in DNA when they chemically attach, or bind, at separate sites to the double-helical molecule that carries life’s genetic blueprint.
Biologists have discovered that the physical manifestation of DNA loops are a consequence of many biochemical processes in the cell, such as the regulation of gene expression. In other words, these loops indicate the presence of enzymes or other proteins that are turned on. Now physicists at the University of California, San Diego have discovered that stretching the DNA molecule can also turn off the proteins known to cause loops in DNA.
“We showed that certain enzymes acting on DNA could be switched off or on simply by applying a small amount of mechanical tension across the DNA molecule,” said Douglas Smith, an assistant professor of physics at UCSD who headed the team that published the discovery in the December issue of the Biophysical Journal. “We showed this by mechanically manipulating and stretching single DNA molecules. This switching effect could provide a molecular mechanism for cells to be able to sense and respond to mechanical stresses that they may normally experience. Such stresses could be generated internally by the cells themselves, such as when the cell undergoes changes in shape during the cell cycle, or as external stresses from the environment.”
The amount of tension or stretching that needs to be applied to the molecule is extremely small, Smith added, only one pico-Newton, or one-trillionth of the force generated by the weight of an apple. Other members of the UCSD team were Gregory Gemmen, a physics graduate student, and Rachel Millin, a laboratory assistant. The study was supported by grants from the Burroughs Wellcome Fund, Kinship Foundation and Arnold and Mabel Beckman Foundation.
http://ucsdnews.ucsd.edu/newsrel/science/dnaloop06.asp 本人已认领该文编译，48小时后若未提交译文，请其他战友自由认领。 本人放弃该文编译，请其他战友自由认领。 本人已认领该文编译，48小时后若未提交译文，请其他战友自由认领。 Stretch a DNA Loop, Turn Off Proteins
打开DNA环，“关闭”蛋白质
It may look like mistletoe wrapped around a flexible candy cane. But this molecular model shows how some proteins form loops in DNA when they chemically attach, or bind, at separate sites to the double-helical molecule that carries life’s genetic blueprint.
就像槲寄生包绕在柔软的甘蔗蔓藤上，分子模型展示了某些蛋白在DNA 如何形成环状，当它们用化学键贴或者绑在携带生命遗传蓝图的双螺旋DNA分子。
Biologists have discovered that the physical manifestation of DNA loops are a consequence of many biochemical processes in the cell, such as the regulation of gene expression. In other words, these loops indicate the presence of enzymes or other proteins that are turned on. Now physicists at the University of California, San Diego have discovered that stretching the DNA molecule can also turn off the proteins known to cause loops in DNA.
生物学家发现DNA环区的物理运动影响着细胞内许多生化过程，如对基因表达的调节。换句话说，这些环区预示着某些被环区活化的酶或蛋白的存在。现在圣地亚哥加利福尼亚大学的物理学家发现DNA分子的伸缩也能使引起DNA 环状的蛋白质变性失活等。
“We showed that certain enzymes acting on DNA could be switched off or on simply by applying a small amount of mechanical tension across the DNA molecule,” said Douglas Smith, an assistant professor of physics at UCSD who headed the team that published the discovery in the December issue of the Biophysical Journal. “We showed this by mechanically manipulating and stretching single DNA molecules. This switching effect could provide a molecular mechanism for cells to be able to sense and respond to mechanical stresses that they may normally experience. Such stresses could be generated internally by the cells themselves, such as when the cell undergoes changes in shape during the cell cycle, or as external stresses from the environment.”
“我们证明了只要对DNA分子使用少量的机械张力，一些作用于DNA的酶会失活或活化。”史密斯.道格拉斯说道，他是圣地亚哥加利福尼亚大学（UCSD）物理学助理教授，带领团队将研究结果发表于《生物物理学报》12月份刊物上，“我们通过机械处理和伸展单个DNA分子证实了这一点。这个转换效应能够提供了一种分子机理：细胞如何能够感觉和应答它们日常经历的机械应激。这些应激可以产生于细胞内部，如在细胞分裂周期时候细胞形态变化，或产生于外部环境。”
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作者:admin@医学,生命科学 2011-05-23 17:14
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