Photoinduced reactivity of the HIV-1 envelope glycoprotein with a membrane-embedded probe reveals insertion of portions of the HIV-1 Gp41 cytoplasmic tail into the viral membrane.
The interactions of HIV-1 Env (gp120-gp41) with CD4 and coreceptors trigger a barrage of conformational changes in Env that drive the membrane fusion process. Various regions of gp41 have profound effects on HIV entry and budding. However, the precise interactions between gp41 and the membrane have not been elucidated. To examine portions of membrane proteins that are embedded in membrane lipids, we have studied photoinduced chemical reactions in membranes using the lipid bilayer specific probe iodonaphthyl azide (INA). Here we show that in addition to the transmembrane anchor, amphipatic sequences in the cytoplasmic tail (CT) of HIV-1 gp41 are labeled by INA. INA labeling of the HIV-1 gp41 CT was similar whether wild-type or a mutant HIV-1 was used with uncleaved p55 Gag, which does not allow entry. These results shed light on the disposition of the HIV-1 gp41 CT with respect to the membrane. Moreover, our data have general implications for topology of membrane proteins and their in situ interactions with the lipid bilayer.
Viard
Mathias
M
Center of Cancer Research Nanobiology Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
Ablan
Sherimay D
SD
Zhou
Ming
M
Veenstra
Timothy D
TD
Freed
Eric O
EO
Raviv
Yossef
Y
Blumenthal
Robert
R
D015704:CD4 Antigens / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D015335:Molecular Probes; D008969:Molecular Sequence Data; D010777:Photochemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D015335:Molecular Probes