PDBsum entry 1nqn

Unknown function

PDB id: 1nqn

Contents

Protein chains

118 a.a. *

111 a.a. *

Waters ×94

* Residue conservation analysis

PDB id:

1nqn

Name:

Unknown function

Title:

Structure of avm-w110k (w110k mutant of avidin)

Structure:

Avidin. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Gallus gallus. Chicken. Organism_taxid: 9031. Gene: avd. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_cell_line: jm109.

Biol. unit:

Tetramer (from PDB file)

Resolution:

1.80Å R-factor: 0.205 R-free: 0.227

Authors:

Y.Pazy,Y.Eisenberg-Domovich,O.H.Laitinen,M.S.Kulomaa,E.A.Bayer, M.Wilchek,O.Livnah

Key ref:

Y.Pazy et al. (2003). Dimer-tetramer transition between solution and crystalline states of streptavidin and avidin mutants. J Bacteriol, 185, 4050-4056. PubMed id: 12837778

Date:

22-Jan-03 Release date: 15-Jul-03

Protein chain

P02701  (AVID_CHICK) -  Avidin from Gallus gallus

Seq: 152 a.a.

Struc: 118 a.a.*

Protein chain

P02701  (AVID_CHICK) -  Avidin from Gallus gallus

Seq: 152 a.a.

Struc: 111 a.a.*

* PDB and UniProt seqs differ at 6 residue positions (black crosses)

J Bacteriol 185:4050-4056 (2003)

PubMed id: 12837778

Dimer-tetramer transition between solution and crystalline states of streptavidin and avidin mutants.

Y.Pazy, Y.Eisenberg-Domovich, O.H.Laitinen, M.S.Kulomaa, E.A.Bayer, M.Wilchek, O.Livnah.

ABSTRACT

The biotin-binding tetrameric proteins, streptavidin from Streptomyces avidinii and chicken egg white avidin, are excellent models for the study of subunit-subunit interactions of a multimeric protein. Efforts are thus being made to prepare mutated forms of streptavidin and avidin, which would form monomers or dimers, in order to examine their effect on quaternary structure and assembly. In the present communication, we compared the crystal structures of binding site W-->K mutations in streptavidin and avidin. In solution, both mutant proteins are known to form dimers, but upon crystallization, both formed tetramers with the same parameters as the native proteins. All of the intersubunit bonds were conserved, except for the hydrophobic interaction between biotin and the tryptophan that was replaced by lysine. In the crystal structure, the binding site of the mutated apo-avidin contains 3 molecules of structured water instead of the 5 contained in the native protein. The lysine side chain extends in a direction opposite that of the native tryptophan, the void being partially filled by an adjacent lysine residue. Nevertheless, the binding-site conformation observed for the mutant tetramer is an artificial consequence of crystal packing that would not be maintained in the solution-phase dimer. It appears that the dimer-tetramer transition may be concentration dependent, and the interaction among subunits obeys the law of mass action.