| 1. |
- Dasgupta, Jhimli, et al.
(author)
-
Structural Basis of Oligosaccharide Receptor Recognition by Human Papillomavirus
- 2011
-
In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 286:4, s. 2617-2624
-
Journal article (peer-reviewed)abstract
- High risk human papillomavirus types 16 (HPV16) and 18 (HPV18) can cause cervical cancer. Efficient infection by HPV16 and HPV18 pseudovirions requires interactions of particles with cell-surface receptor heparan sulfate oligosaccharide. To understand the virus-receptor interactions for HPV infection, we determined the crystal structures of HPV16 and HPV18 capsids bound to the oligosaccharide receptor fragment using oligomeric heparin. The HPV-heparin structures revealed multiple binding sites for the highly negatively charged oligosaccharide fragment on the capsid surface, which is different from previously reported virus-receptor interactions in which a single type of binding pocket is present for a particular receptor. We performed structure-guided mutagenesis to generate mutant viruses, and cell binding and infectivity assays demonstrated the functional role of viral residues involved in heparin binding. These results provide a basis for understanding virus-heparan sulfate receptor interactions critical for HPV infection and for the potential development of inhibitors against HPV infection.
|
|
| 2. |
- Knappe, Maren, et al.
(author)
-
Surface-exposed amino acid residues of HPV16 L1 protein mediating interaction with cell surface heparan sulfate
- 2007
-
In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:38, s. 27913-27922
-
Journal article (peer-reviewed)abstract
- Efficient infection of cells by human papillomaviruses (HPVs) and pseudovirions requires primary interaction with cell surface proteoglycans with apparent preference for species carrying heparan sulfate (HS) side chains. To identify residues contributing to virus/cell interaction, we performed point mutational analysis of the HPV16 major capsid protein, L1, targeting surface-exposed amino acid residues. Replacement of lysine residues 278, 356, or 361 for alanine reduced cell binding and infectivity of pseudovirions. Various combinations of these amino acid exchanges further decreased cell attachment and infectivity with residual infectivity of less than 5% for the triple mutant, suggesting that these lysine residues cooperate in HS binding. Single, double, or triple exchanges for arginine did not impair infectivity, demonstrating that interaction is dependent on charge distribution rather than sequence-specific. The lysine residues are located within a pocket on the capsomere surface, which was previously proposed as the putative receptor binding site. Fab fragments of binding-neutralizing antibody H16.56E that recognize an epitope directly adjacent to lysine residues strongly reduced HS-mediated cell binding, further corroborating our findings. In contrast, mutation of basic surface residues located in the cleft between capsomeres outside this pocket did not significantly reduce interaction with HS or resulted in assembly-deficient proteins. Computer-simulated heparin docking suggested that all three lysine residues can form hydrogen bonds with 2-O-, 6-O-, and N-sulfate groups of a single HS molecule with a minimal saccharide domain length of eight monomer units. This prediction was experimentally confirmed in binding experiments using capsid protein, heparin molecules of defined length, and sulfate group modifications.
|
|
| 3. |
- Orrú, Valeria, et al.
(author)
-
A loss-of-function variant of PTPN22 is associated with reduced risk of systemic lupus erythematosus
- 2009
-
In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 18:3, s. 569-579
-
Journal article (peer-reviewed)abstract
- A gain-of-function R620W polymorphism in the PTPN22 gene, encoding the lymphoid tyrosine phosphatase LYP, has recently emerged as an important risk factor for human autoimmunity. Here we report that another missense substitution (R263Q) within the catalytic domain of LYP leads to reduced phosphatase activity. High-resolution structural analysis revealed the molecular basis for this loss of function. Furthermore, the Q263 variant conferred protection against human systemic lupus erythematosus, reinforcing the proposal that inhibition of LYP activity could be beneficial in human autoimmunity.
|
|
