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Two Tryptophans Are Better Than One in Accelerating Electron Flow through a Protein
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SYSNO ASEP 0500238 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Two Tryptophans Are Better Than One in Accelerating Electron Flow through a Protein Author(s) Takematsu, K. (US)
Williamson, H. (US)
Nikolovski, P. (US)
Kaiser, J. T. (US)
Sheng, Y. (US)
Pospíšil, Petr (UFCH-W)
Towrie, M. (GB)
Heyda, J. (CZ)
Hollas, D. (CZ)
Záliš, Stanislav (UFCH-W) RID, ORCID
Gray, H. B. (US)
Vlček, Antonín (UFCH-W) RID, ORCID
Winkler, J. R. (US)Source Title ACS Central Science. - : American Chemical Society - ISSN 2374-7943
Roč. 5, č. 1 (2019), s. 192-200Number of pages 9 s. Language eng - English Country US - United States Keywords subunit interface ; generation ; excitation ; dynamics Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GA17-01137S GA ČR - Czech Science Foundation (CSF) Method of publishing Open access Institutional support UFCH-W - RVO:61388955 UT WOS 000456525100021 EID SCOPUS 85059803970 DOI 10.1021/acscentsci.8b00882 Annotation 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 angstrom) are inserted between the CuI 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 angstrom away proceeds with a similar to 70 ns time constant, similar to that of a single-tryptophan mutant (similar to 40 ns) with a 19.4 angstrom Re-Cu distance. Time-resolved spectroscopy (luminescence, visible and IR absorption) revealed two rapid reversible electron transfer steps, W124 -> *Re (400-475 ps, K-1 congruent to 3.5-4) and W122 -> W124(center dot+) (7-9 ns, K-2 congruent to 0.55-0.75), followed by a rate-determining (70-90 ns) Cu-I oxidation by W122(+) ca. 11 angstrom away. The photocycle is completed by 120 mu s 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 similar to 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. Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2020 Electronic address http://hdl.handle.net/11104/0292342
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