西亚试剂优势供应上万种化学试剂产品，欢迎各位新老客户咨询、选购！
中国
联系我们
联系方式：400-990-3999 / 邮箱：sales@xiyashiji.com
西亚试剂 —— 品质可靠，值得信赖
HIV-1 Fusion Peptide Decreases Bending Energy, Promotes Curved Fusion Intermediates
Stephanie Tristram-Nagle 1* and John F. Nagle 1
1 Carnegie Mellon University
* To whom correspondence should be addressed. E-mail:
Submitted on March 19, 2007
Revised on April 6, 2007
Accepted on 18 May 2007
A crucial step in HIV infection is fusion between the viral envelope and the T-cell membrane, which must involve intermediate membrane states with high curvature. Our main result from diffuse x-ray scattering is that the bending modulus KC is greatly reduced upon addition of the HIV fusion peptide FP-23 to lipid bilayers. A smaller bending modulus reduces the free energy barriers required to achieve and pass through the highly curved intermediate states and thereby facilitates fusion and HIV infection. The reduction in KC is by a factor of 13 for the thicker, stiffer diC22:1PC bilayers, and by a factor of 3 for DOPC bilayers. The reduction in KC decays exponentially with concentration of FP-23 and the 1/e concentration is less than 1 mole % peptide to lipid, which is well within the physiological range for a fusion site. A secondary result is, when FP-23 is added to the samples which consist of stacks of membranes, that the distance between membranes increases and eventually becomes infinite at full hydration (unbinding); we attribute this both to electrostatic repulsion of the positively charged arginine in the FP-23 and to an increase in the repulsive fluctuation interaction brought about by the smaller KC. While this latter interaction works against membrane fusion, our results show that the energy that it requires of the fusion protein machinery to bring the HIV envelope membrane and the target T-cell membrane into close contact is negligible.
Key Words: Bending Modulus, Biomembrane Fusion, Compression Modulus, Fusion Peptide, HIV-1 Virus, Lipid Membranes
