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J. Virol., 08 1997, 5922-5931, Vol 71, No. 8
M Herrmann, CW von der Lieth, P Stehling, W Reutter and M Pawlita
Polyomaviruses are small, nonenveloped DNA tumor viruses with restricted
host ranges. Virus binding to cell surface receptors is one determinant of
viral tropism. Although murine polyomavirus is among the best characterized
viruses, little is known about the sialic acid- containing receptor and its
interaction with viral particles. By using nonradioactive virus binding
assays as recently described for the B- lymphotropic papovavirus, murine
polyomavirus particles were found to bind in a saturable and noncooperative
manner to 25,000 receptors per 3T6 mouse fibroblast. The virus-receptor
interaction at 4 degrees C was of high affinity (Kd = 1.8 x 10(-11) M),
very fast (k1 = 1.7 x 10(7) M(- 1) s(-1)), and stable (half-life = 38 min).
Elongation of the N-acyl side chain of sialic acid by biosynthetic
modulation with synthetic precursor analogs has been shown for other
polyomaviruses to influence both sialic acid-dependent binding and
infection (O. T. Keppler, P. Stehling, M. Herrmann, H. Kayser, D. Grunow,
W. Reutter, and M. Pawlita, J. Biol. Chem. 270:1308-1314, 1995). In 3T6
cells in which about one-third of the sialic acids were modified, infection
and binding of polyomavirus particles were significantly reduced. The
number of receptors per cell was decreased to 18,000, with the remaining
receptors displaying the same affinity as in untreated cells. Molecular
modeling studies based on the three-dimensional structure of a mouse
polyomavirus-sialyllactose complex recently solved by T. Stehle and
coworkers (T. Stehle, Y. W. Yan, T. L. Benjamin, and S. C. Harrison, Nature
369:160-163, 1994) were performed. They suggest that the elongation of the
N-acyl side chain by a single methylene group leads to steric hinderence,
with the peptide backbone of a loop walling the tip of the shallow sialic
acid binding groove. This collision appears to be incompatible with
functional binding. The data are taken as a basis to discuss possible
features of the organization and topology of the cellular receptor for
mouse polyomavirus.
Copyright © 1997, American Society for Microbiology
Consequences of a subtle sialic acid modification on the murine polyomavirus receptor
Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
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