6p42

Yeast cytochrome c peroxidase (W191Y:L232H) in complex with iso-1 cytochrome c

spinqualitylabelsall models 6p42, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6p42 is a 4 chain structure with sequence from Saccharomyces cerevisiae S288C. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.905Å Ligands: HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CYC1_YEAST Electron carrier protein. The oxidized form of the cytochrome c heme group can accept an electron from the heme group of the cytochrome c1 subunit of cytochrome reductase. Cytochrome c then transfers this electron to the cytochrome oxidase complex, the final protein carrier in the mitochondrial electron-transport chain. Publication Abstract from PubMed 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 c peroxidase (CcP) employs a Trp191(+*) radical to oxidize reduced cytochrome c (Cc). Although a Tyr191 replacement also forms a stable radical, it does not support rapid ET from Cc. 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) rescues 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 Cc oxidation that support an increased Y191(*) reduction potential of approximately 200 mV in the presence of E232. Hence, Y191 inactivity results from a reduction 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 Cc. These findings have implications for the YZ/YD radicals of PS II, hole-hopping in RNR and cryptochrome, and engineering proteins for long-range ET reactions. Tuning radical relay residues by proton management rescues protein electron hopping.,Yee EF, Dzikovski B, Crane BR J Am Chem Soc. 2019 Oct 11. doi: 10.1021/jacs.9b05715. PMID:31603693 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome C 3D structures Cytochrome c peroxidase 3D structures

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