The Radical Site in Chlamydial Ribonucleotide Reductase Defines a New R2 Subclass
- 9 July 2004
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 305 (5681) , 245-248
- https://doi.org/10.1126/science.1098419
Abstract
Ribonucleotide reductase (RNR) synthesizes the deoxyribonucleotides for DNA synthesis. The R2 protein of normal class I ribonucleotide reductases contains a diiron site that produces a stable tyrosyl free radical, essential for enzymatic activity. Structural and electron paramagnetic resonance studies of R2 from Chlamydia trachomatis reveal a protein lacking a tyrosyl radical site. Instead, the protein yields an iron-coupled radical upon reconstitution. The coordinating structure of the diiron site is similar to that of diiron oxidases/monoxygenases and supports a role for this radical in the RNR mechanism. The specific ligand pattern in the C. trachomatis R2 metal site characterizes a new group of R2 proteins that so far has been found in eight organisms, three of which are human pathogens.Keywords
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