6P43

Yeast cytochrome c peroxidase in complex with iso-1 cytochrome c (Y48K)

Summary for 6P43

• Entry DOI: 10.2210/pdb6p43/pdb
• Descriptor: Cytochrome c peroxidase, mitochondrial, Cytochrome c iso-1, PROTOPORPHYRIN IX CONTAINING FE, ... (4 entities in total)
• Functional Keywords: heme proteins, electron hopping, multi-step tunneling, electron transport-oxidoreductase complex, electron transport, electron transport/oxidoreductase
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 3
• Total formula weight: 80923.75

Authors

Yee, E.F.,Crane, B.R. (deposition date: 2019-05-25, release date: 2019-10-23, Last modification date: 2024-10-23)

Primary citation

Yee, E.F.,Dzikovski, B.,Crane, B.R.
Tuning Radical Relay Residues by Proton Management Rescues Protein Electron Hopping.
J.Am.Chem.Soc., 141:17571-17587, 2019

PubMed Abstract: Transient tyrosine and tryptophan radicals play key roles in the electron transfer (ET) reactions of photosystem (PS) II, ribonucleotide reductase (RNR), photolyase, and many other proteins. However, Tyr and Trp are not functionally interchangeable, and the factors controlling their reactivity are often unclear. Cytochrome peroxidase (CcP) employs a Trp191 radical to oxidize reduced cytochrome c (). Although a Tyr191 replacement also forms a stable radical, it does not support rapid ET from . Here we probe the redox properties of CcP Y191 by non-natural amino acid substitution, altering the ET driving force and manipulating the protic environment of Y191. Higher potential fluorotyrosine residues increase ET rates marginally, but only addition of a hydrogen bond donor to Tyr191 (via Leu232His or Glu) substantially alters activity by increasing the ET rate by nearly 30-fold. ESR and ESEEM spectroscopies, crystallography, and pH-dependent ET kinetics provide strong evidence for hydrogen bond formation to Y191 by His232/Glu232. Rate measurements and rapid freeze quench ESR spectroscopy further reveal differences in radical propagation and oxidation that support an increased Y191 formal potential of ∼200 mV in the presence of E232. Hence, Y191 inactivity results from a potential drop owing to Y191 deprotonation. Incorporation of a well-positioned base to accept and donate back a hydrogen bond upshifts the Tyr potential into a range where it can effectively oxidize . These findings have implications for the Y/Y radicals of PS II, hole-hopping in RNR and cryptochrome, and engineering proteins for long-range ET reactions.

PubMed: 31603693
DOI: 10.1021/jacs.9b05715

Experimental method

X-RAY DIFFRACTION (1.913 Å)