Limited solvation of an electron donating tryptophan stabilizes a photoinduced charge-separated state in plant (6-4) photolyase.
Sci Rep
; 12(1): 5084, 2022 03 24.
Article
em En
| MEDLINE
| ID: mdl-35332186
ABSTRACT
(6-4) Photolyases ((6-4) PLs) are ubiquitous photoenzymes that use the energy of sunlight to catalyze the repair of carcinogenic UV-induced DNA lesions, pyrimidine(6-4)pyrimidone photoproducts. To repair DNA, (6-4) PLs must first undergo so-called photoactivation, in which their excited flavin adenine dinucleotide (FAD) cofactor is reduced in one or two steps to catalytically active FADH- via a chain of three or four conserved tryptophan residues, transiently forming FADâ¢-/FADH- ⯠TrpHâ¢+ pairs separated by distances of 15 to 20 Å. Photolyases and related photoreceptors cryptochromes use a plethora of tricks to prevent charge recombination of photoinduced donor-acceptor pairs, such as chain branching and elongation, rapid deprotonation of TrpHâ¢+ or protonation of FADâ¢-. Here, we address Arabidopsis thaliana (6-4) PL (At64) photoactivation by combining molecular biology, in vivo survival assays, static and time-resolved spectroscopy and computational methods. We conclude that At64 photoactivation is astonishingly efficient compared to related proteins-due to two factors exceptionally low losses of photoinduced radical pairs through ultrafast recombination and prevention of solvent access to the terminal Trp3Hâ¢+, which significantly extends its lifetime. We propose that a highly conserved histidine residue adjacent to the 3rd Trp plays a key role in Trp3Hâ¢+ stabilization.
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Base de dados:
MEDLINE
Assunto principal:
Arabidopsis
/
Desoxirribodipirimidina Fotoliase
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article