PDBsum entry 6mjs

Electron transport

PDB id: 6mjs

Contents

Protein chains

128 a.a.

Ligands

REQ ×4

Metals

_CU ×4

Waters ×271

PDB id:

6mjs

Name:

Electron transport

Title:

Azurin 122w/124w/126re

Structure:

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

Source:

Pseudomonas aeruginosa (strain atcc 15692 / dsm 22644 / cip 104116 / jcm 14847 / lmg 12228 / 1c / prs 101 / pao1). Organism_taxid: 208964. Strain: atcc 15692 / dsm 22644 / cip 104116 / jcm 14847 / lmg 12228 / 1c / prs 101 / pao1. Gene: azu, pa4922. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008

Resolution:

1.85Å R-factor: 0.170 R-free: 0.198

Authors:

K.Takematsu,S.Zalis,H.B.Gray,A.Vlcek,J.R.Winkler,H.Williamson, J.T.Kaiser,J.Heyda,D.Hollas

Key ref:

K.Takematsu et al. (2019). Two Tryptophans Are Better Than One in Accelerating Electron Flow through a Protein. ACS Cent Sci, 5, 192-200. PubMed id: 30693338 DOI: 10.1021/acscentsci.8b00882

Date:

21-Sep-18 Release date: 20-Feb-19

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 7 residue positions (black crosses)

DOI no: 10.1021/acscentsci.8b00882

ACS Cent Sci 5:192-200 (2019)

PubMed id: 30693338

Two Tryptophans Are Better Than One in Accelerating Electron Flow through a Protein.

K.Takematsu, H.R.Williamson, P.Nikolovski, J.T.Kaiser, Y.Sheng, P.Pospíšil, M.Towrie, J.Heyda, D.Hollas, S.Záliš, H.B.Gray, A.Vlček, J.R.Winkler.

ABSTRACT

We have constructed and structurally characterized a Pseudomonas aeruginosa azurin mutant Re126WWCu^I , where two adjacent tryptophan residues (W124 and W122, indole separation 3.6-4.1 Å) are inserted between the Cu^I center and a Re photosensitizer coordinated to the imidazole of H126 (Re^I(H126)(CO)₃(4,7-dimethyl-1,10-phenanthroline)⁺). Cu^I oxidation by the photoexcited Re label (*Re) 22.9 Å away proceeds with a ∼70 ns time constant, similar to that of a single-tryptophan mutant (∼40 ns) with a 19.4 Å Re-Cu distance. Time-resolved spectroscopy (luminescence, visible and IR absorption) revealed two rapid reversible electron transfer steps, W124 → *Re (400-475 ps, K₁ ≅ 3.5-4) and W122 → W124^•+ (7-9 ns, K₂ ≅ 0.55-0.75), followed by a rate-determining (70-90 ns) Cu^I oxidation by W122^•+ ca. 11 Å away. The photocycle is completed by 120 μs recombination. No photochemical Cu^I oxidation was observed in Re126FWCu^I , whereas in Re126WFCu^I , the photocycle is restricted to the ReH126W124 unit and Cu^I remains isolated. QM/MM/MD simulations of Re126WWCu^I indicate that indole solvation changes through the hopping process and W124 → *Re electron transfer is accompanied by water fluctuations that tighten W124 solvation. Our finding that multistep tunneling (hopping) confers a ∼9000-fold advantage over single-step tunneling in the double-tryptophan protein supports the proposal that hole-hopping through tryptophan/tyrosine chains protects enzymes from oxidative damage.