Peptide mimics of the vesicular stomatitis virus G-protein transmembrane segment drive membrane fusion in vitro.
The efficiency of cell-cell fusion mediated by heterologously expressed vesicular stomatitis virus G-protein has previously been shown to be affected by mutating its transmembrane segment. Here, we show that a synthetic peptide modeled after this transmembrane segment drives liposome-liposome fusion. Addition of millimolar Ca(2+) concentrations strongly potentiated the effect of the peptides suggesting that Ca(2+)-mediated liposome aggregation supports the activity of the peptide. Peptide-driven fusion was suppressed by lysolipid, an established inhibitor of natural membrane fusion, and involved inner and outer leaflets of the liposomal bilayer. Thus, transmembrane segment peptide-driven liposome fusion exhibits important hallmarks characteristic of natural membrane fusion. Importantly, the mutations previously shown to attenuate the function of full-length G-protein in cell-cell fusion also attenuated the fusogenicity of the peptide, albeit in a less pronounced fashion. Therefore, the function of the peptide mimic is dependent on its primary structure, similar to full-length G-protein. Together, our data suggest that the G-protein transmembrane segment is an autonomous functional domain. We propose that it acts at a late step in membrane fusion elicited by vesicular stomatitis virus.
Langosch
D
D
Department of Neurobiology, Universität Heidelberg, Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany. Langosch@sun0.urz.uni-heidelburg.de
Brosig
B
B
Pipkorn
R
R
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008081:Liposomes; D008561:Membrane Fusion; D008562:Membrane Glycoproteins; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D017354:Point Mutation; D013050:Spectrometry, Fluorescence; D014721:Vesicular stomatitis Indiana virus / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C028391:G protein, vesicular stomatitis virus; D006023:Glycoproteins; D008081:Liposomes; D008562:Membrane Glycoproteins; D010455:Peptides; D014759:Viral Envelope Proteins; D002118:Calcium