6dqx

Actinobacillus ureae class Id ribonucleotide reductase alpha subunit

spinqualitylabelsall models 6dqx, resolution 1.76Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6dqx is a 1 chain structure with sequence from Actinobacillus ureae ATCC 25976. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.76Å Ligands: CL, EDO, GOL, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function E8KJ17_9PAST Publication Abstract from PubMed Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic alpha subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate beta 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 alpha 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 beta subunit association. Class Id RNR activity is insensitive to dATP in the Fj and Au enzymes evaluated here, as expected. However, the class Id alpha 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 alpha 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. Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis.,Rose HR, Maggiolo AO, McBride MJ, Palowitch GM, Pandelia ME, Davis KM, Yennawar NH, Boal AK Biochemistry. 2019 Apr 9;58(14):1845-1860. doi: 10.1021/acs.biochem.8b01252. Epub, 2019 Mar 22. PMID:30855138 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonucleotide reductase 3D structures

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