Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis

Hannah R. Rose, Ailiena O. Maggiolo, Molly J. McBride, Gavin M. Palowitch, Maria Eirini Pandelia, Katherine M. Davis, Neela Yennawar, Amie Kathleen Boal

Research output: Contribution to journalArticle

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Abstract

Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate β subunit. Class Id RNRs use a simple mechanism of cofactor activation involving oxidation of a Mn II 2 cluster by free superoxide to yield a metal-based Mn III Mn IV oxidant. This simple cofactor assembly pathway suggests that class Id RNRs may be representative of the evolutionary precursors to more complex class Ia-c enzymes. X-ray crystal structures of two class Id α proteins from Flavobacterium johnsoniae (Fj) and Actinobacillus ureae (Au) reveal that this subunit is distinctly small. The enzyme completely lacks common N-terminal ATP-cone allosteric motifs that regulate overall activity, a process that normally occurs by dATP-induced formation of inhibitory quaternary structures to prevent productive β subunit association. Class Id RNR activity is insensitive to dATP in the Fj and Au enzymes evaluated here, as expected. However, the class Id α protein from Fj adopts higher-order structures, detected crystallographically and in solution. The Au enzyme does not exhibit these quaternary forms. Our study reveals structural similarity between bacterial class Id and eukaryotic class Ia α subunits in conservation of an internal auxiliary domain. Our findings with the Fj enzyme illustrate that nucleotide-independent higher-order quaternary structures can form in simple RNRs with truncated or missing allosteric motifs.

Original languageEnglish (US)
Pages (from-to)1845-1860
Number of pages16
JournalBiochemistry
Volume58
Issue number14
DOIs
StatePublished - Apr 9 2019

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Ribonucleotide Reductases
Biosynthesis
Flavobacterium
Catalytic Domain
Actinobacillus
Enzymes
Nucleotides
Catalysis
Oxidants
Superoxides
Cones
Conservation
Proteins
Adenosine Triphosphate
Crystal structure
Metals
Chemical activation
X-Rays
Association reactions
X rays

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Rose, Hannah R. ; Maggiolo, Ailiena O. ; McBride, Molly J. ; Palowitch, Gavin M. ; Pandelia, Maria Eirini ; Davis, Katherine M. ; Yennawar, Neela ; Boal, Amie Kathleen. / Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis. In: Biochemistry. 2019 ; Vol. 58, No. 14. pp. 1845-1860.
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Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis. / Rose, Hannah R.; Maggiolo, Ailiena O.; McBride, Molly J.; Palowitch, Gavin M.; Pandelia, Maria Eirini; Davis, Katherine M.; Yennawar, Neela; Boal, Amie Kathleen.

In: Biochemistry, Vol. 58, No. 14, 09.04.2019, p. 1845-1860.

Research output: Contribution to journalArticle

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AU - Rose, Hannah R.

AU - Maggiolo, Ailiena O.

AU - McBride, Molly J.

AU - Palowitch, Gavin M.

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