2Z21

Crystal Structure of a five site mutated Cyanovirin-N

Summary for 2Z21

• Entry DOI: 10.2210/pdb2z21/pdb
• Related: 1IIY 1L5E 1LOM 1M5M 2EZM 2PYS
• Descriptor: Cyanovirin-N (2 entities in total)
• Functional Keywords: cyanovirin-n, sugar binding protein, anti-hiv, gp120
• Biological source: Nostoc ellipsosporum
• Total number of polymer chains: 2
• Total formula weight: 23898.19

Authors

Fromme, R.,Katilene, Z.,Fromme, P.,Ghirlanda, G. (deposition date: 2007-05-17, release date: 2007-07-31, Last modification date: 2024-11-13)

Primary citation

Fromme, R.,Katiliene, Z.,Giomarelli, B.,Bogani, F.,Mahon, J.M.,Mori, T.,Fromme, P.,Ghirlanda, G.
A Monovalent Mutant of Cyanovirin-N Provides Insight into the Role of Multiple Interactions with gp120 for Antiviral Activity.
Biochemistry, 46:9199-9207, 2007

PubMed 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 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.

PubMed: 17636873
DOI: 10.1021/bi700666m

Experimental method

X-RAY DIFFRACTION (1.8 Å)