10.1021\/ja312457t<\/a><\/p>\nAuthors:<\/h4>\n
Joseph A. Cotruvo, Troy A. Stich, R. David Britt, JoAnne Stubbe<\/p>\n
Abstract:<\/h4>\n
Ribonucleotide reductases (RNRs) utilize radical chemistry to reduce nucleotides to deoxynucleotides in all organisms. In the class Ia and Ib RNRs, this reaction requires a stable tyrosyl radical (Y(\u2022)) generated by oxidation of a reduced dinuclear metal cluster. The Fe(III)2-Y(\u2022) cofactor in the NrdB subunit of the class Ia RNRs can be generated by self-assembly from Fe(II)2-NrdB, O2, and a reducing equivalent. By contrast, the structurally homologous class Ib enzymes require a Mn(III)2-Y(\u2022) cofactor in their NrdF subunit. Mn(II)2-NrdF does not react with O2, but it binds the reduced form of a conserved flavodoxin-like protein, NrdIhq, which, in the presence of O2, reacts to form the Mn(III)2-Y(\u2022) cofactor. Here we investigate the mechanism of assembly of the Mn(III)2-Y(\u2022) cofactor in Bacillus subtilis NrdF. Cluster assembly from Mn(II)2-NrdF, NrdI(hq), and O2 has been studied by stopped flow absorption and rapid freeze quench EPR spectroscopies. The results support a mechanism in which NrdI(hq) reduces O2 to O2(\u2022-) (40-48 s(-1), 0.6 mM O2), the O2(\u2022-) channels to and reacts with Mn(II)2-NrdF to form a Mn(III)Mn(IV) intermediate (2.2 \u00b1 0.4 s(-1)), and the Mn(III)Mn(IV) species oxidizes tyrosine to Y(\u2022) (0.08-0.15 s(-1)). Controlled production of O2(\u2022-) by NrdIhq during class Ib RNR cofactor assembly both circumvents the unreactivity of the Mn(II)2 cluster with O2 and satisfies the requirement for an \u00ab\u00a0extra\u00a0\u00bb reducing equivalent in Y(\u2022) generation.<\/p>\n","protected":false},"excerpt":{"rendered":"
DOI: 10.1021\/ja312457t Authors: Joseph A. Cotruvo, Troy A. Stich, R. David Britt, JoAnne Stubbe Abstract: Ribonucleotide reductases (RNRs) utilize radical chemistry to reduce nucleotides to deoxynucleotides in all organisms. In the class Ia and Ib RNRs, this reaction requires a stable tyrosyl radical (Y(\u2022)) generated by oxidation of a reduced dinuclear metal cluster. The Fe(III)2-Y(\u2022) […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-680","post","type-post","status-publish","format-standard","hentry","category-freeze-quench"],"_links":{"self":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/680","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=680"}],"version-history":[{"count":0,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=\/wp\/v2\/posts\/680\/revisions"}],"wp:attachment":[{"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=680"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=680"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/citations.tools.bio-logic.fr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=680"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}