Efficient Growth Inhibition of Bacillus Anthracis by Knocking out the Ribonucleotide Reductase Tyrosyl Radical

Overview

Journal Proc Natl Acad Sci U S A

Specialty Science

Date 2005 Dec 3

PMID 16322104

Citations 25

Authors

Eduard Torrents

Margareta Sahlin

Daniele Biglino

Astrid Graslund

Britt-Marie Sjoberg

Affiliations

Soon will be listed here.

Abstract

Bacillus anthracis, the causative agent of anthrax, is a worldwide problem because of the need for effective treatment of respiratory infections shortly after exposure. One potential key enzyme of B. anthracis to be targeted by antiproliferative drugs is ribonucleotide reductase. It provides deoxyribonucleotides for DNA synthesis needed for spore germination and growth of the pathogen. We have cloned, purified, and characterized the tyrosyl radical-carrying NrdF component of B. anthracis class Ib ribonucleotide reductase. Its EPR spectrum points to a hitherto unknown three-dimensional geometry of the radical side chain with a 60 degrees rotational angle of C(alpha)-(C(beta)-C(1))-plane of the aromatic ring. The unusual relaxation behavior of the radical signal and its apparent lack of line broadening at room temperature suggest a weak interaction with the nearby diiron site and the presence of a water molecule plausibly bridging the phenolic oxygen of the radical to a ligand of the diiron site. We show that B. anthracis cells are surprisingly resistant to the radical scavenger hydroxyurea in current use as an antiproliferative drug, even though its NrdF radical is efficiently scavenged in vitro. Importantly, the antioxidants hydroxylamine and N-methyl hydroxylamine scavenge the radical several orders of magnitude faster and prevent B. anthracis growth at several hundred-fold lower concentrations compared with hydroxyurea. Phylogenetically, the B. anthracis NrdF protein clusters together with NrdFs from the pathogens Bacillus cereus, Bacillus thuringiensis, Staphylococcus aureus, and Staphylococcus epidermidis. We suggest the potential use of N-hydroxylamines in combination therapies against infections by B. anthracis and closely related pathogens.

Citing Articles

Structure of a ribonucleotide reductase R2 protein radical.

Lebrette H, Srinivas V, John J, Aurelius O, Kumar R, Lundin D Science. 2023; 382(6666):109-113.

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The Bacillus anthracis class Ib ribonucleotide reductase subunit NrdF intrinsically selects manganese over iron.

Grave K, Griese J, Berggren G, Bennett M, Hogbom M J Biol Inorg Chem. 2020; 25(4):571-582.

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Redox-induced structural changes in the di-iron and di-manganese forms of Bacillus anthracis ribonucleotide reductase subunit NrdF suggest a mechanism for gating of radical access.

Grave K, Lambert W, Berggren G, Griese J, Bennett M, Logan D J Biol Inorg Chem. 2019; 24(6):849-861.

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Methyl-hydroxylamine as an efficacious antibacterial agent that targets the ribonucleotide reductase enzyme.

Julian E, Baelo A, Gavalda J, Torrents E PLoS One. 2015; 10(3):e0122049.

PMID: 25782003 PMC: 4363900. DOI: 10.1371/journal.pone.0122049.

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