Design of ruthenium-cytochrome c derivatives to measure electron transfer to cytochrome c peroxidase

Liu, R.Q.; Geren, Lois; Anderson, P.; Fairris, Jill L.; Peffer, Nicole; McKee, Ailsa S.; Durham, Bill; Millett, Francis

doi:10.1016/0300-9084(96)88171-5

Cited by 19 publications

(12 citation statements)

References 55 publications

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“…Ru-55-Cc was chosen because it is labeled with ruthenium trisbipyridine at lysine 55 on the bottom of Cc, remote from the binding domain, and should not significantly affect the interaction with CcO (see below). Laser flash photolysis of Ru-55-Cc resulted in rapid electron transfer from Ru(II*) to heme c Fe(III) with a rate constant of 4 ϫ 10 5 s Ϫ1 (26), as shown in Scheme I. The yield of heme c photoreduced by a single laser flash was approximately 2%.…”

Section: Resultsmentioning

confidence: 94%

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

Wang¹,

Zhen²,

Sadoski³

et al. 1999

Journal of Biological Chemistry

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Section: Resultsmentioning

confidence: 94%

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

Wang¹,

Zhen²,

Sadoski³

et al. 1999

Journal of Biological Chemistry

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“…There is a concern that the ruthenium trisbipyridyl group might cause a change in the orientation of Ru-27-Cc at the binding site, raising the question of whether gating is a factor in the reaction of native horse Cc. Studies with a series of horse Ru-Cc derivatives labeled at lysines on the back surface of the protein indicate that the rate constant k eta for electron transfer to the Trp-191 radical cation by native horse Cc is approximately 10 5 s -1 (42). This value is more than 200-fold greater than the k et value of 5 × 10 2 s -1 predicted for the crystalline horse Cc-CcP complex using eq 4.…”

Section: Discussionmentioning

confidence: 94%

Role of Configurational Gating in Intracomplex Electron Transfer from Cytochrome c to the Radical Cation in Cytochrome c Peroxidase

et al. 1999

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Electron transfer within complexes of cytochrome c (Cc) and cytochrome c peroxidase (CcP) was studied to determine whether the reactions are gated by fluctuations in configuration. Electron transfer in the physiological complex of yeast Cc (yCc) and CcP was studied using the Ru-39-Cc derivative, in which the H39C/C102T variant of yeast iso-1-cytochrome c is labeled at the single cysteine residue on the back surface with trisbipyridylruthenium(II). Laser excitation of the 1:1 Ru-39-Cc-CcP compound I complex at low ionic strength results in rapid electron transfer from RuII to heme c FeIII, followed by electron transfer from heme c FeII to the Trp-191 indolyl radical cation with a rate constant keta of 2 x 10(6) s-1 at 20 degrees C. keta is not changed by increasing the viscosity up to 40 cP with glycerol and is independent of temperature. These results suggest that this reaction is not gated by fluctuations in the configuration of the complex, but may represent the elementary electron transfer step. The value of keta is consistent with the efficient pathway for electron transfer in the crystalline yCc-CcP complex, which has a distance of 16 A between the edge of heme c and the Trp-191 indole [Pelletier, H., and Kraut, J. (1992) Science 258, 1748-1755]. Electron transfer in the complex of horse Cc (hCc) and CcP was examined using Ru-27-Cc, in which hCc is labeled with trisbipyridylruthenium(II) at Lys-27. Laser excitation of the Ru-27-Cc-CcP complex results in electron transfer from RuII to heme c FeII with a rate constant k1 of 2.3 x 10(7) s-1, followed by oxidation of the Trp-191 indole to a radical cation by RuIII with a rate constant k3 of 7 x 10(6) s-1. The cycle is completed by electron transfer from heme c FeII to the Trp-191 radical cation with a rate constant k4 of 6.1 x 10(4) s-1. The rate constant k4 decreases to 3.4 x 10(3) s-1 as the viscosity is increased to 84 cP, but the rate constants k1 and k3 remain the same. The results are consistent with a gating mechanism in which the Ru-27-Cc-CcP complex undergoes fluctuations between a major state A with the configuration of the hCc-CcP crystalline complex and a minor state B with the configuration of the yCc-CcP complex. The hCc-CcP complex, state A, has an inefficient pathway for electron transfer from heme c to the Trp-191 indolyl radical cation with a distance of 20.5 A and a predicted value of 5 x 10(2) s-1 for k4A. The observed rate constant k4 is thus gated by the rate constant ka for conversion of state A to state B, where the rate of electron transfer k4B is expected to be 2 x 10(6) s-1. The temperature dependence of k4 provides activation parameters that are consistent with the proposed gating mechanism. These studies provide evidence that configurational gating does not control electron transfer in the physiological yCc-CcP complex, but is required in the nonphysiological hCc-CcP complex.

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“…Bovine CcO was prepared as described by Pan et al . The preparation of Ru-55- Cc was carried out as described by Liu et al The Rs . CcO wild-type and mutants were prepared as described by Zhen et al…”

Section: Methodsmentioning

confidence: 99%

Definition of the Interaction Domain and Electron Transfer Route between Cytochrome c and Cytochrome Oxidase

et al. 2019

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The reaction between cytochrome c (Cc) and cytochrome c oxidase (CcO) was studied using horse cytochrome c derivatives labeled with ruthenium trisbipyridine at Cys 39 (Ru-39-Cc). Flash photolysis of a 1:1 complex between Ru-39-Cc and bovine CcO at a low ionic strength resulted in the electron transfer from photoreduced heme c to Cu A with an intracomplex rate constant of k 3 = 6 × 10 4 s −1 . The K13A, K72A, K86A, and K87A Ru-39-Cc mutants had nearly the same k 3 value but bound much more weakly to bovine CcO than wild-type Ru-39-Cc, indicating that lysines 13, 72, 86, and 87 were involved in electrostatic binding to CcO, but were not involved in the electron transfer pathway. The Rhodobacter sphaeroides (Rs) W143F mutant (bovine W104) caused a 450-fold decrease in k 3 but did not affect the binding strength with CcO or the redox potential of Cu A . These results are consistent with a computational model for Cc−CcO (Roberts and Pique (1999) J. Biol. Chem. 274, 38051−38060) with the following electron transfer pathway: heme c → CcO-W104 → CcO-M207 → Cu A . A crystal structure for the Cc−CcO complex with the proposed electron transfer pathway heme c → Cc-C14 → Cc-K13 → CcO-Y105 → CcO-M207 → Cu A (S. Shimada et al. (2017) EMBO J. 36, 291−300) is not consistent with the kinetic results because the K13A mutation had no effect on k 3 . Addition of 40% ethylene glycol (as present during the crystal preparation) decreased k 3 significantly, indicating that it affected the conformation of the complex. This may explain the discrepancy between the current results and the crystallographic structure.

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Design of ruthenium-cytochrome c derivatives to measure electron transfer to cytochrome c peroxidase

Cited by 19 publications

References 55 publications

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

Role of Configurational Gating in Intracomplex Electron Transfer from Cytochrome c to the Radical Cation in Cytochrome c Peroxidase

Definition of the Interaction Domain and Electron Transfer Route between Cytochrome c and Cytochrome Oxidase

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