title: Direct Measurement of the Radical Translocation Distance in the Class I Ribonucleotide Reductase from Chlamydia trachomatis.
abstract: Ribonucleotide reductases (RNRs) catalyze conversion of ribonucleotides to deoxyribonucleotides in all organisms via a free-radical mechanism that is essentially conserved. In class I RNRs, the reaction is initiated and terminated by radical translocation (RT) between the α and β subunits. In the class Ic RNR from Chlamydia trachomatis (Ct RNR), the initiating event converts the active S = 1 Mn(IV)/Fe(III) cofactor to the S = 1/2 Mn(III)/Fe(III) "RT-product" form in the β subunit and generates a cysteinyl radical in the α active site. The radical can be trapped via the well-described decomposition reaction of the mechanism-based inactivator, 2'-azido-2'-deoxyuridine-5'-diphosphate, resulting in the generation of a long-lived, nitrogen-centered radical (N(•)) in α. In this work, we have determined the distance between the Mn(III)/Fe(III) cofactor in β and N(•) in α to be 43 ± 1 Å by using double electron-electron resonance experiments. This study provides the first structural data on the Ct RNR holoenzyme complex and the first direct experimental measurement of the inter-subunit RT distance in any class I RNR.
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Jovan
authors.initials: J
authors.lastname: Livada
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Martinie
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Laura M K
authors.initials: LM
authors.lastname: Dassama
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Carsten
authors.initials: C
authors.lastname: Krebs
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: J Martin
authors.initials: JM
authors.lastname: Bollinger
authors.affiliation: Departments of †Chemistry and ‡Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Alexey
authors.initials: A
authors.lastname: Silakov
mesh_terms: D002692:Chlamydia trachomatis / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D012264:Ribonucleotide Reductases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D005609:Free Radicals; D012264:Ribonucleotide Reductases