Investigation Of GP41 Fusion Protein By Sum Frequency Generation Vibrational Spectroscopy

Membrane Fusion activity exists widely in our life body,it participates in significant material transfer and information exchange process.GP41,the HIV virus envelope protein which is a kind of typical membrane fusion protein,plays a complicated and significant role in the process of virus infection.The FP segment is located at the N-terminal of GP41 protein and it can decrease the distance between virus membrane and host cell membrane at the beginning of fusion.Because of its vital function,there are plenty of studies in regard to the GP41 N-terminal domain(FP),they mainly concentrate on the structure of the GP41 N-terminal domain.It is accepted that GP41 FP can form ?-strand and ?-sheet structure.It is reported recently that the multiple?-strand structure of GP41 FP can insert into the membrane more deeply and can facilitate membrane fusion via changing the topological structure of membrane.However,due to its structural diversity and lack of efficient technique,the structure characterization of ?-strand structure remains to be a huge challenge and the exact molecular mechanism between the fusion process and the protein aggregate behavior of GP41 FP is still unfathomed.The key point to solve these problems is to develop a technique which is sensitive at the interface in real time and in situ.And sum frequency generation vibrational spectroscopy is proved to meet these requirements and is widely used in protein and lipid researches.In this study,we successfully applied amide ??amide ??amide ? and amide A SFG signals and combined chiral and achiral polarizations to investigate the structure and dynamics of GP41 membrane fusion peptide in different lipid membrane at different timeline.The results show that GP41 appears different structure at different peptide concentration,the increase of concentration will induce the P-sheet structure aggregates into oligomer which is reflected in SFG amide ? spectra.And the extension of time and the raising of temperature will facilitate the aggregate extent of GP41.Meantime,we discovered that the segmental sequence change will also influence the structure of the whole protein to a great extent.