Locations of carbohydrate sites on alphavirus glycoproteins show that E1 forms an icosahedral scaffold.
There are 80 spikes on the surface of Sindbis virus arranged as an icosahedral surface lattice. Each spike consists of three copies of each of the glycoproteins E1 and E2. There are two glycosylation sites on E1 and two on E2. These four sites have been located by removal of the glycosylation recognition motifs using site-specific mutagenesis, followed by cryoelectron microscopy. The positions of these sites have demonstrated that E2 forms the protruding spikes and that E1 must be long and narrow, lying flat on the viral surface, forming an icosahedral scaffold analogous to the arrangement of the E glycoprotein in flaviviruses. This arrangement of E1 leads to both dimeric and trimeric intermolecular contacts, consistent with the observed structural changes that occur on fusion with host cell membranes, suggesting a similar fusion mechanism for alpha- and flaviviruses.
Pletnev
Sergei V
SV
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Zhang
Wei
W
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Mukhopadhyay
Suchetana
S
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Fisher
Bonnie R
BR
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Hernandez
Raquel
R
Department of Molecular and Structural Biochemistry North Carolina State University Raleigh, North Carolina 27695.
Brown
Dennis T
DT
Department of Molecular and Structural Biochemistry North Carolina State University Raleigh, North Carolina 27695.
Baker
Timothy S
TS
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Rossmann
Michael G
MG
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
Kuhn
Richard J
RJ
Department of Biological Sciences Purdue University West Lafayette, Indiana 47907.
D000524:Alphavirus / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure*; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002241:Carbohydrates / Q000737:chemistry*; D002460:Cell Line; D006224:Cricetinae; D020285:Cryoelectron Microscopy; D004669:Encephalitis Viruses, Tick-Borne / Q000737:chemistry; D006031:Glycosylation; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D012398:Ross River virus / Q000737:chemistry; D012845:Sindbis Virus / Q000737:chemistry / Q000648:ultrastructure; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics; D014760:Viral Fusion Proteins / Q000737:chemistry* / Q000235:genetics
D002241:Carbohydrates; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; C022012:glycoprotein E1, Sindbis virus; C064950:glycoprotein E2, Sindbis virus