PDBsum entry 2gi0

Electron transport

PDB id: 2gi0

Contents

Protein chains

128 a.a. *

Metals

CU1 ×2

Waters ×317

* Residue conservation analysis

PDB id:

2gi0

Name:

Electron transport

Title:

Crystal structure of cu(i) phe114pro azurin mutant

Structure:

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

Source:

Pseudomonas aeruginosa. Organism_taxid: 287. Gene: azu. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.70Å R-factor: 0.181 R-free: 0.224

Authors:

S.Yanagisawa,M.J.Banfield,C.Dennison

Key ref:

S.Yanagisawa et al. (2006). The role of hydrogen bonding at the active site of a cupredoxin: the Phe114Pro azurin variant. Biochemistry, 45, 8812-8822. PubMed id: 16846224

Date:

28-Mar-06 Release date: 04-Jul-06

Protein chains

P00282  (AZUR_PSEAE) -  Azurin from Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)

Seq: 148 a.a.

Struc: 128 a.a.*

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

Biochemistry 45:8812-8822 (2006)

PubMed id: 16846224

The role of hydrogen bonding at the active site of a cupredoxin: the Phe114Pro azurin variant.

S.Yanagisawa, M.J.Banfield, C.Dennison.

ABSTRACT

The Phe114Pro mutation to the cupredoxin azurin (AZ) leads to a number of structural changes at the active site attributed to deletion of one of the hydrogen bonds to the Cys112 ligand, removal of the bulky phenyl group from the hydrophobic patch of the protein, and steric interactions made by the introduced Pro. The remaining hydrogen bond between the coordinating thiolate and the backbone amide of Asn47 is strengthened. At the type-1 copper site, the Cu(II)-O(Gly45) axial interaction decreases, while the metal moves out of the plane formed by the equatorial His46, Cys112, and His117 ligands, shortening the bond to the axially coordinating Met121. The resulting distorted tetrahedral geometry is distinct from the trigonal bipyramidal arrangement in the wild-type (WT) protein. The unique position of the main S(Cys) --> Cu(II) ligand-to-metal charge-transfer transition in AZ (628 nm) has shifted in the Phe114Pro variant to a value that is more typical for cupredoxins (599 nm). This probably occurs because of the removal of the Phe114-Cys112 hydrogen bond. The Phe114Pro mutation results in a 90 mV decrease in the reduction potential of AZ, and removal of the second hydrogen bond to the Cys ligand seems to be the major cause of this change. The C-terminal His117 ligand does not protonate in the reduced Phe114Pro AZ variant, which suggests that none of the structural features altered by the mutation are responsible for the absence of this effect in the WT protein. Upon reduction, the copper displaces further from the equatorial ligand plane and the Cu-S(Met121) bond length decreases. These changes are larger than those seen in the WT protein and contribute to the order of magnitude decrease in the intrinsic electron-transfer capabilities of the Phe114Pro variant.