2z21
From Proteopedia
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Crystal Structure of a five site mutated Cyanovirin-N
Overview
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 A, 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.
About this Structure
2Z21 is a Single protein structure of sequence from Nostoc ellipsosporum. Full crystallographic information is available from OCA.
Reference
A Monovalent Mutant of Cyanovirin-N Provides Insight into the Role of Multiple Interactions with gp120 for Antiviral Activity(,)., Fromme R, Katiliene Z, Giomarelli B, Bogani F, Mahon JM, Mori T, Fromme P, Ghirlanda G, Biochemistry. 2007 Jul 18;. PMID:17636873
Page seeded by OCA on Thu Nov 8 14:57:38 2007
