Theoretical Insights into the Generation Mechanism of the Tyr122 Radical Catalyzed by Intermediate X in Class Ia Ribonucleotide Reductase

Nian Liu, Li Li, Xin Qin, Xin Li, Yuxin Xie, Xiaohua Chen, Jiali Gao

Research output: Contribution to journalArticlepeer-review

Abstract

Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides in all organisms. There is an ∼35 Å long-range electron-hole transfer pathway during the catalytic process of class Ia RNR, which can be described as Tyr122β ↔ [Trp48β]? ↔ Tyr356β ↔ Tyr731α ↔ Tyr730α ↔ Cys439α. The formation of the Y122 radical initiates this long-range radical transfer process. However, the generation mechanism of Y122 is not yet clear due to confusion over the intermediate X structures. Based on the two reported X structures, we examined the possible mechanisms of Y122 generation by density functional theory (DFT) calculations. Our examinations revealed that the generation of the Y122 radical from the two different core structures of X was via a similar two-step reaction, with the first step of proton transfer for the formation of the proton receptor of Y122 and the second step of a proton-coupled long-range electron transfer reaction with the proton transfer from the Y122 hydroxyl group to the terminal hydroxide ligand of Fe1III and simultaneously electron transfer from the side chain of Y122 to Fe2IV. These findings provide an insight into the formation mechanism of Y122 catalyzed by the double-iron center of the β subunit of class Ia RNR.

Original languageEnglish (US)
Pages (from-to)19498-19506
Number of pages9
JournalInorganic chemistry
Volume62
Issue number48
DOIs
StatePublished - Dec 4 2023

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© 2023 American Chemical Society.

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