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PDBsum entry 4j4f
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Sugar binding protein
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PDB id
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4j4f
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References listed in PDB file
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Key reference
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Title
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Different 3d domain-Swapped oligomeric cyanovirin-N structures suggest trapped folding intermediates.
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Authors
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L.M.Koharudin,
L.Liu,
A.M.Gronenborn.
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Ref.
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Proc Natl Acad Sci U S A, 2013,
110,
7702-7707.
[DOI no: ]
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PubMed id
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Abstract
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Although it has long been established that the amino acid sequence encodes the
fold of a protein, how individual proteins arrive at their final conformation is
still difficult to predict, especially for oligomeric structures. Here, we
present a comprehensive characterization of oligomeric species of cyanovirin-N
that all are formed by a polypeptide chain with the identical amino acid
sequence. Structures of the oligomers were determined by X-ray crystallography,
and each one exhibits 3D domain swapping. One unique 3D domain-swapped structure
is observed for the trimer, while for both dimer and tetramer, two different 3D
domain-swapped structures were obtained. In addition to the previously
identified hinge-loop region of the 3D domain-swapped dimer, which resides
between strands β5 and β6 in the middle of the polypeptide sequence, another
hinge-loop region is observed between strands β7 and β8 in the structures.
Plasticity in these two regions allows for variability in dihedral angles and
concomitant differences in chain conformation that results in the differently 3D
domain-swapped multimers. Based on all of the different structures, we propose
possible folding pathways for this protein. Altogether, our results illuminate
the amazing ability of cyanovirin-N to proceed down different folding paths and
provide general insights into oligomer formation via 3D domain swapping.
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