The N-glycan of the SCR 2 region is essential for membrane cofactor protein (CD46) to function as a measles virus receptor.
Membrane cofactor protein (MCP) (CD46), a complement-regulatory protein, serves as a cellular receptor for measles virus. Its amino-terminal portion is composed of four short consensus repeats (SCR), three of which (SCR1, SCR2, and SCR4) carry an N-linked oligosaccharide. In order to determine the importance of the three N-glycans for the function of MCP as a measles virus receptor, we established Chinese hamster ovary (CHO) cell lines that stably express mutant MCPs lacking one of the three motifs for N glycosylation (NQ1, NQ2, and NQ4). In an additional mutant (NQ1-2), two glycosylation motifs were altered, allowing the addition of an N-linked oligosaccharide only in SCR4. The abilities of the mutant MCPs to function as measles virus receptors were analyzed with three different assays: (i) binding of measles virus hemagglutinin to MCP immobilized on nitrocellulose; (ii) binding of measles virus to CHO cells expressing wild-type or mutant MCP; and (iii) infection of the transfected CHO cells by measles virus. In all three assays, the abilities of the NQ2 and NQ1-2 mutants to serve as measles virus receptors were drastically impaired. The NQ1 and NQ4 mutants were recognized by measles virus almost as efficiently as the wild-type protein. These results indicate that the N-glycan attached to SCR2 is essential for MCP to serve as a measles virus receptor, while the oligosaccharides attached to SCR1 and SCR4 are of only minor importance.
Maisner
A
A
Institut für Virologie, Philipps-Universität Marburg, Germany.
Alvarez
J
J
Liszewski
M K
MK
Atkinson
D J
DJ
Atkinson
J P
JP
Herrler
G
G
D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D008457:Measles / Q000378:metabolism / Q000821:virology*; D008459:Measles virus / Q000378:metabolism*; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D011134:Polysaccharides / Q000378:metabolism*; D011991:Receptors, Virus / Q000737:chemistry / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid
D015703:Antigens, CD; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D011134:Polysaccharides; D011991:Receptors, Virus