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The RGD sequence in the cytomegalovirus DNA polymerase accessory protein can mediate cell adhesion
L C Loh1, D Locke, R Melnychuk
1Department of Microbiology, Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, S7N 5E5 Canada, loh@sask.usask.ca
Virology
|June 30, 2000
Summary
Murine cytomegalovirus ppM44 protein binds cells via its RGD motif, suggesting a novel role in viral replication beyond its function as a polymerase processivity factor.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Murine cytomegalovirus (MCMV) polymerase processivity factor ppM44 is an abundant phosphoprotein.
- Sequence analysis revealed an RGD motif in MCMV ppM44, also found in human cytomegalovirus (HCMV) UL44.
Purpose of the Study:
- To investigate the function of the MCMV ppM44 protein.
- To determine if the RGD motif in ppM44 mediates cell adhesion.
- To explore potential roles of ppM44 in the MCMV replication cycle.
Main Methods:
- Purification of histidine-tagged M44 protein using metal chelation affinity chromatography.
- Assessing cell adhesion mediated by recombinant M44 protein.
- Mutagenesis of the RGD motif (RGD to RGE) to evaluate its role in cell attachment.
- Testing the effect of EDTA on cell adhesion.
- Evaluating cell adhesion mediated by recombinant HCMV UL44 and human herpesvirus type 6 p41.
Main Results:
- Recombinant M44 protein mediated cell adhesion through its RGD motif.
- Mutation of the RGD motif abolished cell attachment.
- EDTA treatment also abolished cell adhesion, indicating an integrin-binding mechanism.
- Recombinant HCMV UL44, but not HHV-6 p41, showed similar cell adhesion properties.
- ppM44 was detected in the culture medium during MCMV infection.
Conclusions:
- MCMV ppM44 functions as a cell adhesion molecule via its RGD motif.
- This RGD motif is conserved in HCMV UL44.
- ppM44 may act as an integrin-binding substrate, suggesting a novel role in MCMV replication.