1z3c
From Proteopedia
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'''Encephalitozooan cuniculi mRNA Cap (Guanine-N7) Methyltransferasein complexed with AzoAdoMet''' | '''Encephalitozooan cuniculi mRNA Cap (Guanine-N7) Methyltransferasein complexed with AzoAdoMet''' | ||
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[[Category: Encephalitozoon cuniculi]] | [[Category: Encephalitozoon cuniculi]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: mRNA (guanine-N(7)-)-methyltransferase]] | ||
[[Category: Fabrega, C.]] | [[Category: Fabrega, C.]] | ||
[[Category: Hausmann, S.]] | [[Category: Hausmann, S.]] | ||
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[[Category: Shuman, S.]] | [[Category: Shuman, S.]] | ||
[[Category: Zhang, S.]] | [[Category: Zhang, S.]] | ||
| - | [[Category: | + | [[Category: Azoadomet]] |
| - | [[Category: | + | [[Category: Cap]] |
| - | [[Category: | + | [[Category: M7g]] |
| - | [[Category: | + | [[Category: Messenger rna cap]] |
| - | [[Category: | + | [[Category: Methyltransferase]] |
| - | [[Category: | + | [[Category: Rna]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:07:57 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 14:07, 3 May 2008
Encephalitozooan cuniculi mRNA Cap (Guanine-N7) Methyltransferasein complexed with AzoAdoMet
Overview
The Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase Ecm1 has been characterized structurally but not biochemically. Here we show that purified Ecm1 is a monomeric protein that catalyzes methyl transfer from S-adenosylmethionine (AdoMet) to GTP. The reaction is cofactor-independent and optimal at pH 7.5. Ecm1 also methylates GpppA, GDP, and dGTP but not ATP, CTP, UTP, ITP, or m(7)GTP. The affinity of Ecm1 for the cap dinucleotide GpppA (K 0.1 mm) is higher than that for GTP (K(m) 1 mm) or GDP (K(m) 2.4 mm). Methylation of GTP by Ecm1 in the presence of 5 microm AdoMet is inhibited by the reaction product AdoHcy (IC(50) 4 microm) and by substrate analogs sinefungin (IC(50) 1.5 microm), aza-AdoMet (IC(50) 100 microm), and carbocyclic aza-AdoMet (IC(50) 35 microm). The crystal structure of an Ecm1.aza-AdoMet binary complex reveals that the inhibitor occupies the same site as AdoMet. Structure-function analysis of Ecm1 by alanine scanning and conservative substitutions identified functional groups necessary for methyltransferase activity in vivo. Amino acids Lys-54, Asp-70, Asp-78, and Asp-94, which comprise the AdoMet-binding site, and Phe-141, which contacts the cap guanosine, are essential for cap methyltransferase activity in vitro.
About this Structure
1Z3C is a Single protein structure of sequence from Encephalitozoon cuniculi. Full crystallographic information is available from OCA.
Reference
Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis., Hausmann S, Zheng S, Fabrega C, Schneller SW, Lima CD, Shuman S, J Biol Chem. 2005 May 27;280(21):20404-12. Epub 2005 Mar 9. PMID:15760890 Page seeded by OCA on Sat May 3 17:07:57 2008
