Previous Article | Next Article ![]()
J. Virol., May 1997, 3458-3465, Vol 71, No. 5
L Rong, A Edinger and P Bates
Receptor specificity in avian sarcoma and leukosis viruses (ASLV) maps to
the central region of the envelope surface protein, SU. Two hypervariable
regions, hr1 and hr2, within this region of SU are the principal
determinants of receptor specificity. The cellular receptor for subgroup A
ASLV, Tva, utilizes a 40-residue, acidic, cysteine-rich sequence for viral
binding and entry. This domain in Tva is closely related to the
ligand-binding domain of the low-density lipoprotein receptor (LDLR).
Ligands bind to LDLR via the interaction of clustered basic residues in the
ligand with the acidic cysteine-rich domains of the receptor. Analysis of
the ASLV envelope sequences revealed a cluster of basic residues within hr2
that is unique to the subgroup A viruses, suggesting a possible role for
these residues in receptor recognition. Therefore, the effects of altering
these basic residues on subgroup A envelope expression, receptor binding,
and infectivity were examined. Most of the mutant proteins were transported
to the cell surface and processed normally. Receptor binding was diminished
approximately 50% by alanine substitution at amino acid R213 or K227,
whereas substitution by alanine at R210, R223, or R224 had no effect.
However, when coupled with mutations at R213 or K227, changes at R223,R224
reduced envelope binding by 90%. Mutation of all five basic residues
abrogated receptor binding. The effect of the hr2 mutations on ASLV
envelope-mediated infection did not parallel the effect on receptor
binding. Residues 210, 213, 223, and 224 were important for efficient
infection, while mutations at residue 227 had little effect on infectivity.
These results demonstrate that the basic residues in the ASLV envelope have
roles in both receptor recognition and post- receptor binding events during
viral entry.
Copyright © 1997, American Society for Microbiology
Role of basic residues in the subgroup-determining region of the subgroup A avian sarcoma and leukosis virus envelope in receptor binding and infection
Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|