Abstract
UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its α3 domain with an affinity that is ∼1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18α3 domain is not sufficient per se for binding and that β2-microglobulin is necessary for UL18-CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the α2 and α3 domains and specific amino acids within them were identified that are potentially involved in the UL18-CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.
| Original language | English |
|---|---|
| Pages (from-to) | 957-968 |
| Number of pages | 12 |
| Journal | Journal of Immunology |
| Volume | 180 |
| Issue number | 2 |
| Publication status | Published - Jan 15 2008 |
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ASJC Scopus subject areas
- Immunology
Cite this
Dissecting the structural determinants of the interaction between the human cytomegalovirus UL18 protein and the CD85j immune receptor. / Occhino, Marzia; Ghiotto, Fabio; Soro, Simonetta; Mortarino, Mimosa; Bosi, Stefania; Maffei, Massimo; Bruno, Silvia; Nardini, Marco; Figini, Mariangela; Tramontano, Anna; Ciccone, Ermanno.
In: Journal of Immunology, Vol. 180, No. 2, 15.01.2008, p. 957-968.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Dissecting the structural determinants of the interaction between the human cytomegalovirus UL18 protein and the CD85j immune receptor
AU - Occhino, Marzia
AU - Ghiotto, Fabio
AU - Soro, Simonetta
AU - Mortarino, Mimosa
AU - Bosi, Stefania
AU - Maffei, Massimo
AU - Bruno, Silvia
AU - Nardini, Marco
AU - Figini, Mariangela
AU - Tramontano, Anna
AU - Ciccone, Ermanno
PY - 2008/1/15
Y1 - 2008/1/15
N2 - UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its α3 domain with an affinity that is ∼1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18α3 domain is not sufficient per se for binding and that β2-microglobulin is necessary for UL18-CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the α2 and α3 domains and specific amino acids within them were identified that are potentially involved in the UL18-CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.
AB - UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its α3 domain with an affinity that is ∼1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18α3 domain is not sufficient per se for binding and that β2-microglobulin is necessary for UL18-CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the α2 and α3 domains and specific amino acids within them were identified that are potentially involved in the UL18-CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.
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UR - http://www.scopus.com/inward/citedby.url?scp=40449096658&partnerID=8YFLogxK
M3 - Article
C2 - 18178836
AN - SCOPUS:40449096658
VL - 180
SP - 957
EP - 968
JO - Journal of Immunology
JF - Journal of Immunology
SN - 0022-1767
IS - 2
ER -