1vbf
Crystal structure of protein L-isoaspartate O-methyltransferase homologue from Sulfolobus tokodaii
|
OverviewOverview
To study how oligomerization may contribute to the thermostability of, archaeon proteins, we focused on a hexameric protein, protein, L-isoaspartyl-O-methyltransferase from Sulfolobus tokodaii (StoPIMT). The, crystal structure shows that StoPIMT has a distinctive hexameric structure, composed of monomers consisting of two domains: an, S-adenosylmethionine-dependent methyltransferase fold domain and a, C-terminal alpha-helical domain. The hexameric structure includes three, interfacial contact regions: major, minor, and coiled-coil. Several, C-terminal deletion mutants were constructed and characterized. The, hexameric structure and thermostability were retained when the C-terminal, alpha-helical domain (Tyr(206)-Thr(231)) was deleted, suggesting that, oligomerization via coiled-coil association using the C-terminal, alpha-helical domains did not contribute critically to hexamerization or, to the increased thermostability of the protein. Deletion of three, additional residues located in the major contact region, Tyr(203)-Asp(204)-Asp(205), led to a significant decrease in hexamer, stability and chemico/thermostability. Although replacement of Thr(146), and Asp(204), which form two hydrogen bonds in the interface in the major, contact region, with Ala did not affect hexamer formation, these mutations, led to a significant decrease in thermostability, suggesting that two, residues in the major contact region make significant contributions to the, increase in stability of the protein via hexamerization. These results, suggest that cooperative hexamerization occurs via interactions of "hot, spot" residues and that a couple of interfacial hot spot residues are, responsible for enhancing thermostability via oligomerization.
About this StructureAbout this Structure
1VBF is a Single protein structure of sequence from Sulfolobus tokodaii. Active as Protein-L-isoaspartate(D-aspartate) O-methyltransferase, with EC number 2.1.1.77 Full crystallographic information is available from OCA.
ReferenceReference
How oligomerization contributes to the thermostability of an archaeon protein. Protein L-isoaspartyl-O-methyltransferase from Sulfolobus tokodaii., Tanaka Y, Tsumoto K, Yasutake Y, Umetsu M, Yao M, Fukada H, Tanaka I, Kumagai I, J Biol Chem. 2004 Jul 30;279(31):32957-67. Epub 2004 May 27. PMID:15169774
Page seeded by OCA on Sat Nov 24 22:01:21 2007