3S5X: Structure Of The Cyanobacterial Oscillatoria Agardhii Agglutinin (oaa) In Complex With A3,a6 Mannopentaose

The cyanobacterial Oscillatory Agardhii agglutinin (OAA) is a recently discovered HIV-inactivating lectin that interacts with high-mannose sugars. Nuclear magnetic resonance (NMR) binding studies between OAA and alpha3,alpha6-mannopentaose (Manalpha(1-3)[Manalpha(1-3)[Manalpha(1-6)]Manalpha(1-6)]Man), the branched core unit of Man-9, revealed two binding sites at opposite ends of the protein, exhibiting essentially identical affinities. Atomic details of the specific protein-sugar contacts in the recognition loops of OAA were delineated in the high-resolution crystal structures of free and glycan-complexed protein. No major changes in the overall protein structure are induced by carbohydrate binding, with essentially identical apo- and sugar-bound conformations in binding site 1. A single peptide bond flip at W77-G78 is seen in binding site 2. Our combined NMR and crystallographic results provide structural insights into the mechanism by which OAA specifically recognizes the branched Man-9 core, distinctly different from the recognition of the D1 and D3 arms at the nonreducing end of high-mannose carbohydrates by other antiviral lectins.
PDB ID: 3S5XDownload
MMDB ID: 92017
PDB Deposition Date: 2011/5/23
Updated in MMDB: 2014/11
Experimental Method:
x-ray diffraction
Resolution: 1.65  Å
Source Organism:
Similar Structures:
Biological Unit for 3S5X: monomeric; determined by author and by software (PISA)
Molecular Components in 3S5X
Label Count Molecule
Protein (1 molecule)
Molecule annotation
Chemicals (10 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB