Abstract
Cyanovirin-N (CV-N) is a 101 amino acid cyanobacterial lectin with potent antiviral activity against HIV, mediated by high-affinity binding to branched N-linked oligomannosides on the viral surface envelope protein gp120. The protein contains two carbohydrate-binding domains, A and B, each of which binds short oligomannosides independently in vitro. The interaction to gp120 could involve either a single domain or both domains simultaneously; it is not clear which mode would elicit the antiviral activity. The model is complicated by the formation of a domain-swapped dimer form, in which part of each domain is exchanged between two monomers, which contains four functional carbohydrate-binding domains. To clarify whether multivalent interactions with gp120 are necessary for the antiviral activity, we engineered a novel mutant, P51G-m4-CVN, in which the binding site on domain A has been knocked out; in addition, a [P51G] mutation prevents the formation of domain-swapped dimers under physiological conditions. Here, we present the crystal structures at 1.8 Å of the free and of the dimannose-bound forms of P51G-m4-CVN, revealing a monomeric structure in which only domain B is bound to dimannose. P51G-m4-CVN binds gp120 with an affinity almost 2 orders of magnitude lower than wt CV-N and is completely inactive against HIV. The tight binding to gp120 is recovered in the domain-swapped version of P51G-m4-CVN, prepared under extreme conditions. Our findings show that the presence of at least two oligomannoside-binding sites, either by the presence of intact domains A and B or by formation of domain-swapped dimers, is essential for activity.
Original language | English (US) |
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Pages (from-to) | 9199-9207 |
Number of pages | 9 |
Journal | Biochemistry |
Volume | 46 |
Issue number | 32 |
DOIs | |
State | Published - Aug 14 2007 |
ASJC Scopus subject areas
- Biochemistry
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Crystal Structure of a five site mutated Cyanovirin-N
Fromme, R. (Contributor), Katiliene, Z. (Contributor), Giomarelli, B. (Contributor), Bogani, F. (Contributor), Mc Mahon, J. (Contributor), Mori, T. (Contributor), Fromme, P. (Contributor) & Ghirlanda, G. (Contributor), Protein Data Bank (PDB), Jul 31 2007
DOI: 10.2210/pdb2Z21, https://www.wwpdb.org/pdb?id=pdb_00002z21
Dataset
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Crystal Structure of a Five Site Mutated Cyanovirin-N with a Mannose Dimer Bound at 1.8 A Resolution
Fromme, R. (Contributor), Katiliene, Z. (Contributor), Giomarelli, B. (Contributor), Bogani, F. (Contributor), Mc Mahon, J. (Contributor), Mori, T. (Contributor), Fromme, P. (Contributor) & Ghirlanda, G. (Contributor), Protein Data Bank (PDB), Jul 31 2007
DOI: 10.2210/pdb2PYS, https://www.wwpdb.org/pdb?id=pdb_00002pys
Dataset