生物谷报道：最新的《Nature》杂志上的一项研究，揭示了第一个肽链的形成的机制。核糖体不在一个mRNA的末端启动转录过程，相反，它们会结合到一个内部点（Shine-Dalgarno (SD)序列）上，然后单向转位。对断开核糖体的mRNA 和 30S部分之间的结合所需的力进行的精确测量显示，在第一个肽链形成之前，SD序列稳定核糖体-mRNA的相互作用。一旦该肽链形成，SD序列就不再稳定它。所以，最初肽链的形成是核糖体释放SD的一个触发因素，而且还可能是允许核糖体开始沿mRNA 运动的一个重要因素。
FIGURE 1. Experimental design for rupture force measurements on the ribosome
a, The molecular attachments within the mRNA–ribosome–bead complex. Ribosomal particles were assembled on a short mRNA tethered to the surface via biotin–streptavidin linkage. A digoxigenin-modified oligonucleotide was designed to hybridize to an rRNA loop extension on the small ribosomal subunit (see magnified view at bottom). A bead coated with anti-digoxigenin antibody was conjugated to the oligonucleotide and used for optical trapping of the ribosomal complex. The sequence 'AGGA' on the mRNA designates the strong SD region, 'AUGUUU' indicates the first two codons of the mRNA, (N)25 and (N)15 specify the number of residues in the upstream and downstream regions, respectively, and 'Biotin Avidin Biotin-BSA' indicates the details of mRNA attachment to the surface. b, The tethered ribosome–bead complex fluctuates around the point of surface attachment. The two parallel lines within the ribosome signify the two tRNAs bound at the A and P sites. c, Optical tweezers are used to trap the bead. d, As the stage with the attached ribosome–bead complex is moved in one direction, the force exerted on the complex increases and the bead becomes displaced. e, Eventually the external force becomes sufficient to rupture the complex, and the bead returns to the trap centre position.
原文出处：
Nature Volume 446 Number 7134
Peptide bond formation destabilizes Shine–Dalgarno interaction on the ribosome p454
Sotaro Uemura, Magdalena Dorywalska, Tae-Hee Lee, Harold D. Kim, Joseph D. Puglisi and Steven Chu
doi:10.1038/nature05625
First paragraph | Full Text | PDF (845K) | Supplementary information
作者简介：
Steven Chu
朱棣文：出生日期; 民国卅七年二月二八日; 籍贯; 江苏省太仓县; 专习学科; 物理应用物理; 现职; 美国史丹福大学物理学和应用物理教授; 教育背景. 1970年毕业于罗彻斯特大学，获数学学士和物理学学士。 1976年获加州大学伯克利分校物理学博士。
Professor, Physics and Applied Physics --
On Extended Leave from Stanford Faculty
As of August 1, 2004:
Director of LBL (Lawrence Berkeley Labs)
Research Interests
Atomic Physics:
We are continuing to develop new methods of laser cooling and trapping and to apply those methods in a variety of problems. Examples of applications include the use of an atom interferometer to measure the fine structure constant to unprecedented accuracy, the use Bose condensates in optical lattices to study many body effects related to condensed matter systems.
Biological Physics:
We apply single molecule techniques such as fluorescence resonance energy transfer, atomic force microscopy and optical tweezers, we study enzyme activity, and protein and RNA folding at the single bio-molecule level. Systems being studied include how the ribosome reads m-RNA and manufactures proteins, how vesicles fuse into the cell wall at the synapse of neurons, how cells adhere to each other via adhesive molecules, and how RNA molecules fold into active enzymes.
Polymer physics:
We study polymer dynamics and phase transitions associated with these dynamics using individual molecules of DNA as model polymers.
Experimental Atomic Physics Quantum Electronics Laser Physics Biophysics Polymer Physics
Career History
Theodore and Frances Geballe Professor of Physics and Applied Physics A.B. and B.S., 1970, University of Rochester Ph.D., 1976, University of California at Berkeley Postdoctoral Fellow, U.C. Berkeley, 1976-78 Member, Technical Staff, AT&T, 1978-83 Head of Quantum Electronic Dept., AT&T Bell Laboratories, 1983-87 Professor of Physics and Applied Physics, Stanford University, 1987-present Morris Loeb Lecturer, 1988 Special Visitor to JILA, 1989, 1999 Visiting Professor, College de France, 1990
Awards
Fellow of the American Physical Society, 1987 Fellow of the Optical Society of America, 1990 Am. Phys. Soc., Broida Prize for Laser Spectroscopy, 1987 APS/AAPT Richtmyer Memorial Prize Lecture, 1990 Co-winner of the King Faisal International Prize for Science, 1993 Am. Phys. Soc., Arthur Schawlow Prize for Laser Science, 1994 Opt. Soc. Am., William F. Meggers Award for Spectroscopy, 1994 Fellow of the American Academy of Arts and Sciences, 1992 Member of the National Academy of Sciences, 1993 Member of the Academia Sinica, 1994 Science for art Prize and Humboldt Senior Scientist Award, 1995 Guggenhein fellow, 1996 Co-recipient of the Nobel Prize for Physics, 1997 Member of the American Philosophical Society, 1998 Chinese Academy of Sciences, Foreign Member,1998 Korean Academy of Sciences and Technology, Foreign member, 1998
