PDBsum entry 4j4f

Sugar binding protein

PDB id: 4j4f

Contents

Protein chains

101 a.a.

Waters ×316

PDB id:

4j4f

Name:

Sugar binding protein

Title:

Structure of p51g cyanovirin-n swapped tetramer in the p212121 space group

Structure:

Cyanovirin-n. Chain: d, c, b, a. Synonym: cv-n. Engineered: yes. Mutation: yes

Source:

Nostoc ellipsosporum. Organism_taxid: 45916. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.239 R-free: 0.284

Authors:

L.M.I.Koharudin,L.Liu,A.M.Gronenborn

Key ref:

L.M.Koharudin et al. (2013). Different 3D domain-swapped oligomeric cyanovirin-N structures suggest trapped folding intermediates. Proc Natl Acad Sci U S A, 110, 7702-7707. PubMed id: 23610431 DOI: 10.1073/pnas.1300327110

Date:

06-Feb-13 Release date: 03-Apr-13

Protein chains

P81180  (CVN_NOSEL) -  Cyanovirin-N from Nostoc ellipsosporum

Seq: 101 a.a.

Struc: 101 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1073/pnas.1300327110

Proc Natl Acad Sci U S A 110:7702-7707 (2013)

PubMed id: 23610431

Different 3D domain-swapped oligomeric cyanovirin-N structures suggest trapped folding intermediates.

L.M.Koharudin, L.Liu, A.M.Gronenborn.

ABSTRACT

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.