PDBsum entry 4mfh

Electron transport

PDB id: 4mfh

Contents

Protein chains

128 a.a.

Ligands

TRS ×3

Metals

_CU ×6

Waters ×341

PDB id:

4mfh

Name:

Electron transport

Title:

Crystal structure of m121g azurin

Structure:

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

Source:

Pseudomonas aeruginosa. Organism_taxid: 287. Gene: azu, pa4922. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.54Å R-factor: 0.172 R-free: 0.194

Authors:

S.Tian,Y.Lu

Key ref:

N.A.Sieracki et al. (2014). Copper-sulfenate complex from oxidation of a cavity mutant of Pseudomonas aeruginosa azurin. Proc Natl Acad Sci U S A, 111, 924-929. PubMed id: 24390543 DOI: 10.1073/pnas.1316483111

Date:

27-Aug-13 Release date: 15-Jan-14

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)

DOI no: 10.1073/pnas.1316483111

Proc Natl Acad Sci U S A 111:924-929 (2014)

PubMed id: 24390543

Copper-sulfenate complex from oxidation of a cavity mutant of Pseudomonas aeruginosa azurin.

N.A.Sieracki, S.Tian, R.G.Hadt, J.L.Zhang, J.S.Woertink, M.J.Nilges, F.Sun, E.I.Solomon, Y.Lu.

ABSTRACT

Metal-sulfenate centers are known to play important roles in biology and yet only limited examples are known due to their instability and high reactivity. Herein we report a copper-sulfenate complex characterized in a protein environment, formed at the active site of a cavity mutant of an electron transfer protein, type 1 blue copper azurin. Reaction of hydrogen peroxide with Cu(I)-M121G azurin resulted in a species with strong visible absorptions at 350 and 452 nm and a relatively low electron paramagnetic resonance gz value of 2.169 in comparison with other normal type 2 copper centers. The presence of a side-on copper-sulfenate species is supported by resonance Raman spectroscopy, electrospray mass spectrometry using isotopically enriched hydrogen peroxide, and density functional theory calculations correlated to the experimental data. In contrast, the reaction with Cu(II)-M121G or Zn(II)-M121G azurin under the same conditions did not result in Cys oxidation or copper-sulfenate formation. Structural and computational studies strongly suggest that the secondary coordination sphere noncovalent interactions are critical in stabilizing this highly reactive species, which can further react with oxygen to form a sulfinate and then a sulfonate species, as demonstrated by mass spectrometry. Engineering the electron transfer protein azurin into an active copper enzyme that forms a copper-sulfenate center and demonstrating the importance of noncovalent secondary sphere interactions in stabilizing it constitute important contributions toward the understanding of metal-sulfenate species in biological systems.