HIV-1 gp41N端融合肽与脂膜作用的荧光及单分子层膜研究

我们以前的实验证明ＨＩＶ－１ｇｐ４１Ｎ端２３肽即融合肽ＨＩＶｗｔ能促融合，但它的突变体ＨＩＶＧｌｕ（２位Ｖ→Ｅ）却不能诱发融合。为了进一步研究多肽结构与功能的关系，我们用荧光及单分子层膜技术研究ＨＩＶｗｔ及ＨＩＶＧｌｕ与脂的相互作用。荧光淬灭实验表明ＨＩＶｗｔ插入带负电磷脂并插入较深；而ＨＩＶＧｌｕ虽然能与带负电脂结合但并不插膜。单层膜实验进一步证实了上述结果：ＨＩＶｗｔ对带负电磷脂ＰＯＰＧ的临界插膜压达到４３ｍＮ／ｍ，而ＨＩＶＧｌｕ的临界插膜压只有３１ｍＮ／ｍ。这提示ＨＩＶｗｔ与单层膜不仅存在静电作用还有较强的疏水作用。结合上述实验结果推测ＨＩＶｗｔ能插入脂膜的酰基链因而容易促发融合；而ＨＩＶＧｌｕ插膜很浅或根本不能入膜从而不能促融合

INTERACTION OF HIV-1 gp41 N TERMINAL FUSION PEPTIDE WITHPHOSPHOLIPIDS BY FLUORESCENCE AND MONOMOLECULARLAYER TECHNIQUES

Our previous study showed that HIV-1 gp 41 N terminal 23 peptide(HIVwt) was potent to induce fusion while its mutant(HIVGlu)(with only the second position Val substituted by Glu) was not. In an attempt to establish a relationship between peptide structure and function, we have investigated in a liposomal system the activity of these two peptides by fluorescence spectra, fluorescence quenching and also with monomolecular layer techniques. The experiment of fluorescence quenching showed that HIVwt inserted deeply into negatively charged phospholipid membrance; HIVGlu did not insert into lipids though it did bind with lipids. A monomolecular layer study further confirmed the above results. For negatively charged lipids the insertion ability of HIVwt is significantly higher than that into neutral ones. In the case of POPG monolayer, the critical insertion pressure of HIVwt was 43mN/m, while HIVGlu was 31mN/m. only. It showed that the insertion of HIVwt into phospholipid monolayers was driven not only by electrostatic force but also by hydrophobic interactions. The results suggest that HIVwt can insert into acyl chains of membrane and thus it is easy to facilitate fusion. HIVGlu may be unable insert into the membrane or only slightly inserted, much less than HIVwt, so it cannot induce membrane fusion.