The fusion peptide domain is the primary membrane-inserted region and enhances membrane interaction of the ectodomain of HIV-1 gp41.
To execute the membrane fusion function, it is necessary for the fusion protein of the virus to penetrate into the hydrophobic milieu of membrane bilayer. Hence identification of the region(s) of the ectodomain of viral fusion proteins involved in the membrane insertion and their interaction with the rest of the fusion protein in the membrane would be important for the mechanistic study of membrane fusion. To this end, we examined membrane activity of the fusion peptide, and the ectodomain protein with or without the fusion peptide domain of HIV-1 gp41 by several biophysical measurements. The results revealed that the ectodomain protein containing the fusion peptide domain had higher membrane-perturbing activity and deeper membrane insertion, while the construct lacking the fusion peptide domain had much lower membrane activity. Strikingly, the N-terminal heptad repeat region was found to be induced deeper into the membrane by the fusion peptide, consistent with the role of the latter in the membrane penetration. We concluded that the fusion peptide is the only stretch of gp41 ectodomain that embeds deeply in the membrane interior in the prefusion stage. The function of fusion peptide in terms of membrane interaction and the implications of its interplay with other domains of gp41 on the membrane fusion cascade were discussed.
Cheng
Shu-Fang
SF
Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Republic of China.
Chien
Miao-Ping
MP
Lin
Chi-Hui
CH
Chang
Chung-Chieh
CC
Lin
Chun-Hung
CH
Liu
Yu-Tsan
YT
Chang
Ding-Kwo
DK
D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008561:Membrane Fusion; D008567:Membranes, Artificial; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology
D015700:HIV Envelope Protein gp41; D008567:Membranes, Artificial; D010455:Peptides; C514787:gp41 protein, Human immunodeficiency virus 1