Science：丙肝病毒复制酶的作用机制被揭示

生物谷

生物谷报道：最近，研究人员确定了一个对丙肝病毒DNA复制至关重要的酶的机制。这个名为NS3的酶是新的丙肝治疗法的靶标，它的作用是打开DNA和RNA使其得以复制。该研究结果发表在最新一期的《科学》杂志上。

Sua Myong和同事用单分子光谱学方法观察了NS3沿丙肝病毒DNA双螺旋的“蠕动”。这个酶每步打开三个DNA碱基对。(碱基对是DNA双股上对应的由氢键连接的核苷酸。)但是，在碱基对打开之前，还有隐藏的步骤。这个酶先是一、二大步、然后一个小步爬上碱基对，直到张力足够大从而导致解卷和三个碱基对看起来是同时的开链。

NS3酶的作用机制的揭示，对于研究丙肝病毒DNA的复制过程具有重要的指导作用。

Fig. 1. NS3 unwinds DNA in 3-bp steps. (A) PD1, a DNA with 18 double strands (ds) and 20 single strands (ss), was labeled with donor (Cy3) and acceptor (Cy5) at the ds-ss junction and was tethered to a polyethylene glycol surface by 3' biotin. (B) Cy3 (green) and Cy5 (red) intensities monitored during unwinding of a single PD1 molecule (raw time traces in light color, three-point averaged traces in dark color). (C) Calculated FRET efficiency versus time for the molecule shown in (B). (D and E) Two more examples of FRET traces of PD1. (F) PD2 is thesameconstruct as in (A) but prepared with dyes in the middle of duplex. (G to J) Plots analogous to those in (B) to (E) for PD2.

原文出处：

Science 27 July 2007 Vol 317, Issue 5837,

Spring-Loaded Mechanism of DNA Unwinding by Hepatitis C Virus NS3 Helicase

Sua Myong, Michael M. Bruno, Anna M. Pyle, and Taekjip Ha
Science 27 July 2007: 513-516.
A helicase enzyme unwinds DNA in steps three base pairs long that periodically release the tension resulting from translocation of the helicase's motor domain along the DNA.
Abstract »| Full Text »| PDF »| Supporting Online Material »|

作者简介：

Taekjip Ha

Associate Professor of Physics and Howard Hughes Medical Institute Investigator

Professor Taekjip Ha received his Ph.D. in Physics in 1996 from the University of California, Berkeley. Prior to joining the Physics faculty at the University of Illinois in August 2000, he was a postdoctoral fellow at Lawrence Berkeley National Laboratory (1997) and a postdoctoral research associate in Steven Chu's laboratory in the Department of Physics at Stanford University (1998-2000). He was named 2001 Searle scholar. In 2005, Dr. Ha was named an investigator of the Howard Hughes Medical Institute.

Professor Ha has achieved many "firsts" in experimental biological physics--the first dectection of dipole-dipole interaction (fluorescence resonance energy transfer, or FRET) between two single molecules; the first observation of "quantum jumps" of single molecules at room temperature; the first detection of the rotation of single molecules; and the first detection of enzyme conformational changes via single-molecule FRET. His most recent work, using single-molecule measurements to understand protein-DNA interactions and enzyme dynamics, has led him to develop novel optical techniques, fluid-handling systems, and surface preparations.

Research Area : We are interested in using physical concepts and experimental techniques to study fundamental questions in molecular biology. Our main experimental tool is single-molecule fluorescence spectroscopy and microscopy, supported by nano-mechanical tools such as magnetic and optical tweezers. The biological systems under study include helicases that unzip DNA, DNA recombination intermediate called Holliday junction and its associated enzymes, folding and catalysis of ribozymes, DNA replication machinery, chromatin remodeling complexes, and membrane-binding proteins.

Research Group Home Page

Selected Publications

I. Rasnik, S. A. McKinney, and T. Ha, "Non-blinking and Long-lasting Single Molecule Fluorescence Imaging," Nature Methods 3, 891-893 (2006)

C. Joo, S. A McKinney, M. Nakamura, I. Rasnik, S. Myong, and T. Ha, "Real Time Observation of RecA Filament Dynamics with Single Monomer Resolution," Cell 126, 515-527 (2006) ( pdf )

C. Buranachai, S. A. McKinney, and T. Ha, "Single Molecule Nanometronome", Nano Letters 102, 18938-18943 (2006) ( pdf )

S. Myong, I. Rasnik, C. Joo, T. M. Lohman, and T. Ha, "Repetitive Shuttling of a Motor Protein on DNA", Nature 437, 1321-1325 (2005) ( pdf )

Honors and Awards

Searle Scholar Award, 2001
Research Innovation Award, Research Corporation, 2001
Outstanding Young Researcher Award, AKPA, 2001
National Science Foundation CAREER Award, 2002
Fluorescence Young Investigator Award, The Biophysical Society, 2002
Fellow, Alfred P. Sloan Foundation, 2003
Beckman Fellow, Center for Advanced Study, University of Illinois, 2003
Xerox Faculty Research Award, College of Engineering, University of Illinois, 2003
Cottrell Scholars Award, Research Corporation, 2003
Howard Hughes Medical Institute Investigator, 2005
Fellow, American Physical Society, 2005
Michael and Kate Bárány Award for Young Investigators, Biophysical Society, 2007