1mgt

From Proteopedia

Revision as of 19:17, 20 November 2007

CRYSTAL STRUCTURE OF O6-METHYLGUANINE-DNA METHYLTRANSFERASE FROM HYPERTHERMOPHILIC ARCHAEON PYROCOCCUS KODAKARAENSIS STRAIN KOD1

Overview

The crystal structure of O6-methylguanine-DNA methyltransferase (EC, 2.1.1.63) of hyperthermophilic archaeon Pyrococcuskodakaraensis strain, KOD1 (Pk -MGMT) was determined by single isomorphous replacement method, with anomalous scattering (SIRAS) at 1.8 A resolution. The archaeal, protein is extremely thermostable and repairs alkylated DNA by suicidal, alkyl transfer from guanine O6 to its own cysteine residue. Archaea, constitute the third primary kingdom of living organisms, sharing, characteristics with procaryotic and eucaryotic cells. They live in, various extreme environments and are thought to include the most ancient, organisms on the earth. Structural studies on hyperthermophilic archaeal, proteins reveal the structural features essential for stability under the, extreme environments in which these organisms live, and will provide the, structural basis required for stabilizing various mesophilic proteins for, industrial applications. Here, we report the crystal structure of Pk-MGMT, and structural comparison of Pk-MGMT and methyltransferase homologue from, Escherichia coli (AdaC, C-terminal fragment of Ada protein). Analyses of, solvent-accessible surface area (SASA) reveals a large discrepancy between, Pk-MGMT and AdaC with respect to the property of the ASA. In the Pk-MGMT, structure, the intra-helix ion-pairs contribute to reinforce stability of, alpha-helices. The inter-helix ion-pairs exist in the interior of Pk-MGMT, and stabilize internal packing of tertiary structure. Furthermore, structural features of helix cappings, intra and inter-helix ion-pairs are, found around the active-site structure in Pk-MGMT.

About this Structure

1MGT is a Single protein structure of sequence from Thermococcus kodakarensis with SO4 as ligand. Active as [protein-cysteine_S-methyltransferase Methylated-DNA--[protein]-cysteine S-methyltransferase], with EC number 2.1.1.63 Full crystallographic information is available from OCA.

Reference

Hyperthermostable protein structure maintained by intra and inter-helix ion-pairs in archaeal O6-methylguanine-DNA methyltransferase., Hashimoto H, Inoue T, Nishioka M, Fujiwara S, Takagi M, Imanaka T, Kai Y, J Mol Biol. 1999 Sep 24;292(3):707-16. PMID:10497033 [[Category: Methylated-DNA--[protein]-cysteine S-methyltransferase]]

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