Aromatic hole superexchange through position 82 of cytochrome c is not required for intracomplex electron transfer to zinc cytochrome c peroxidase

Everest, Andrew M.; Wallin, Sten A.; Stemp, Eric D. A.; Nocek, Judith M.; Mauk, A. Grant; Hoffman, Brian M.

doi:10.1021/ja00011a050

Cited by 51 publications

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“…The ET kinetics and relative reactivity of all four Cc Phe-82 mutants (Table 1) agree remarkably well with previous solution studies of the same variants (12). Thus, the crystal associations likely represent the 1:1 complexes formed in solution.…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccsupporting

confidence: 86%

“…As seen in solution studies of these systems (12), all of the mutant complexes have a variable slow phase (k eb 2 ϭ 30-70 s Ϫ1 , f 2 ϭ 0.08-0.22) associated with the back ET process (Table 1). This slow phase could reflect direct Fe(II) to Zn-porphyrin ϩ ET, as seen in the CcP W191F mutant (18); however, short-circuit through Trp-191 ϩ should greatly limit porphyrin-porphyrin ET, provided the porphyrin and indolyl radicals rapidly interconvert relative to the interfacial ET reaction.…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 85%

“…Highly conserved Cc Phe-82 lies adjacent to the heme and contributes 13.0 Å 2 of buried surface area to the interface with CcP. Mutations at Phe-82 modestly affect yCc stability, structure, and redox potential (33)(34)(35) and reduce rates of back ET from Fe(II)Cc to ZnCcP ϩ in comparison with WT Cc (12). We mutated Phe-82 of yCc to Tyr, Trp, Ser, and Ile and determined the crystallographic structures of all four variants in complex with yeast CcP (Table 2).…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

“…As such, interprotein ET is sensitive to structure and dynamics at the interface (1,(4)(5)(6)(7)(8)(9)(10)(11). Residue substitution (achieved either by use of protein homologs, site-directed mutants, or computations) has been a popular and powerful approach for probing how interface composition influences interprotein ET (7,(10)(11)(12)(13)(14). Nevertheless, effects of residue variation on interface structure are not often known.…”

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confidence: 99%

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Effects of interface mutations on association modes and electron-transfer rates between proteins

Kang

Crane

2005

Proc. Natl. Acad. Sci. U.S.A.

109

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Although bonding networks determine electron-transfer (ET) rates within proteins, the mechanism by which structure and dynamics influence ET across protein interfaces is not well understood. Measurements of photochemically induced ET and subsequent charge recombination between Zn-porphyrin-substituted cytochrome c peroxidase and cytochrome c in single crystals correlate reactivity with defined structures for different association modes of the redox partners. Structures and ET rates in crystals are consistent with tryptophan oxidation mediating charge recombination reactions. Conservative mutations at the interface can drastically affect how the proteins orient and dispose redox centers. Whereas some configurations are ET inactive, the wild-type complex exhibits the fastest recombination rate. Other association modes generate ET rates that do not correlate with predictions based on cofactor separations or simple bonding pathways. Inhibition of photoinduced ET at <273 K indicates gating by smallamplitude dynamics, even within the crystal. Thus, different associations achieve states of similar reactivity, and within those states conformational fluctuations enable interprotein ET.cytochrome ͉ protein dynamics ͉ protein-protein interaction ͉ electron tunneling M any long-range electron-transfer (ET) reactions in biology occur across transient protein-protein interfaces. Reaction rates depend on factors that control both electron tunneling and conformational dynamics coupled to protein association processes (1-3). As such, interprotein ET is sensitive to structure and dynamics at the interface (1, 4-11). Residue substitution (achieved either by use of protein homologs, site-directed mutants, or computations) has been a popular and powerful approach for probing how interface composition influences interprotein ET (7,(10)(11)(12)(13)(14). Nevertheless, effects of residue variation on interface structure are not often known.The natural redox partners yeast cytochrome c peroxidase (CcP) and yeast cytochrome c (yCc), whose structure as a complex was first determined in 1992 (15) and later as a covalent complex (16), have served as a paradigm for studying interprotein ET reactions (8,17). Hoffman and colleagues (8) have exploited ZnCcP substitution to photoactivate ET reactions and examine the effects of many structural and chemical perturbations on interprotein ET. In this system, the ZnCcP triplet state ( 3 ZnCcP) reduces Fe(III)Cc, and then back ET recombines the charge separation (Fig. 1). Recently, it has been demonstrated that a Trp-191 3 Phe CcP variant has much slower ET back-rates (k eb ) than wild-type (WT) CcP in the 1:1 complex with yCc (18). Thus, electron hopping through Trp-191 may accelerate the recombination reaction (Fig. 1), in analogy to the natural reaction between CcP compound I and Fe(II)Cc (19). Nevertheless, much slower ET back-rates in the complex between CcP and hCc compared with yCc, both in solution (20) and in crystals (21), indicate that ET across the protein-protein interface limits the overa...

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Section: Structures and Redox Properties Of Znccp In Complex With Yccsupporting

confidence: 86%

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 85%

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of interface mutations on association modes and electron-transfer rates between proteins

Kang

Crane

2005

Proc. Natl. Acad. Sci. U.S.A.

109

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“…Despite significant advances in our understanding of long-range electron transfer in biological systems (McLendon, 1988;Gray & Malmstrom, 1989), many factors controlling protein-protein electron transfer remain ill defined. Although recent attention has focused upon the role of the protein-protein interface in the attenuation of electron transfer rates (Peery & KostiE, 1989;Hazzard et al, 1989;Everest et al, 1991;Nocek et al, 1991), no detailed structural information is available concerning the exact interfacial contacts between this or any other pair of electron transfer proteins. The involvement of charged residues in the specificity and stabilization of electrostatic complexes between a variety of electron transfer proteins is well documented (KostiS, 1991), though little is known about the pH dependence of these reactions.…”

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confidence: 99%

Proton linkage of complex formation between cytochrome c and cytochrome b5: electrostatic consequences of protein-protein interactions

Mr¹,

Pd²,

Ag³

1991

Biochemistry

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Two potentiometric methods have been used to study the pH-dependent changes in proton binding that accompany complex formation between cytochrome c and cytochrome b5. With one method, the number of protons bound or released upon addition of one cytochrome to the other has been measured as a function of pH. The results from these studies are correlated with the complexation-induced difference titration curve calculated from the titration curves of the preformed complex and of the individual proteins. Both methods demonstrate that complex formation at acid pH is accompanied by proton release, that complex formation at basic pH is accompanied by proton uptake, and that the change in proton binding at neutral pH, where stability of complex formation is maximal, is relatively small. Under all conditions studied, the stoichiometry of cytochrome c-cytochrome b5 complex formation is 1:1 with no evidence of higher order complex formation. Although the dependence of complex formation on pH for interaction between different species of cytochrome c and cytochrome b5 are qualitatively similar, they are quantitatively different. In particular, complex formation between yeast iso-1-cytochrome c and lipase-solubilized bovine cytochrome b5 occurs with a stability constant that is 10-fold greater than observed for the other two pairs of proteins under all conditions studied. Interaction between these two proteins is also significantly less dependent on ionic strength than observed for complexes formed by horse heart cytochrome c with either form of cytochrome b5.(ABSTRACT TRUNCATED AT 250 WORDS)

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DNA double-helix-mediated long-range electron transfer

Priyadarshy

Beratan

Risser

1996

Int. J. Quantum Chem.

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rnA theoretical analysis based upon large-scale self-consistent Hartree-Fock calculations at a semiempirical quantum theory level (CNDO/S) is performed to investigate long-range electron transfer in a donor-DNA-acceptor molecule, where the donor and acceptor moieties are tethered to the DNA. The r-stacked base pairs are found to dominate the long-range electronic coupling. Despite the r-electron mediated coypling, the exponential distance decay constant of the electron transfer rate is -1.2-1.6 A-', values typical of electron transfer proteins. The calculated lons-range electron transfer rate of the order of lo6 s-' for a metal-to-metal distance of 21 A is found to be in agreement with kinetic measurements by Meade and Kayyem. Based on the current analysis, the r-electrons dominate the long-range electronic coupling interactions in DNA, but they do not lead to one-dimensional molecular wire-like properties. 0 1996 John Wiley & Sons, Inc.tions can play a significant role in the ET process. Yet, the structure-property relationships that control these electronic couplings are not well understood in nucleic acids. Questions have been raised in the past about the role of rr and rr-rr stacking interactions in long-range ET, although experimental evidence of rr-electron effects in macromolecule ET has been elusive [6-131. Recently, the study of Murphy et al. [14] suggested an extremely fast electron transfer rate (lo9 S K ' ) for a metal-to-metal distance of > 40 A between partially intercalated

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Aromatic hole superexchange through position 82 of cytochrome c is not required for intracomplex electron transfer to zinc cytochrome c peroxidase

Cited by 51 publications

References 0 publications

Effects of interface mutations on association modes and electron-transfer rates between proteins

Effects of interface mutations on association modes and electron-transfer rates between proteins

Proton linkage of complex formation between cytochrome c and cytochrome b5: electrostatic consequences of protein-protein interactions

DNA double-helix-mediated long-range electron transfer

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