PDBsum entry 1z3c

Transferase

PDB id: 1z3c

Contents

Protein chain

252 a.a. *

Ligands

SA8

Waters ×132

* Residue conservation analysis

PDB id:

1z3c

Name:

Transferase

Title:

Encephalitozooan cuniculi mRNA cap (guanine-n7) methyltransferasein complexed with azoadomet

Structure:

mRNA capping enzyme. Chain: a. Engineered: yes

Source:

Encephalitozoon cuniculi. Organism_taxid: 6035. Gene: ecu10_0380. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.20Å R-factor: 0.222 R-free: 0.270

Authors:

S.Hausmann,S.Zhang,C.Fabrega,S.W.Schneller,C.D.Lima,S.Shuman

Key ref:

S.Hausmann et al. (2005). Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis. J Biol Chem, 280, 20404-20412. PubMed id: 15760890 DOI: 10.1074/jbc.M501073200

Date:

11-Mar-05 Release date: 22-Mar-05

Protein chain

Q8SR66  (MCES_ENCCU) -  mRNA cap guanine-N7 methyltransferase from Encephalitozoon cuniculi (strain GB-M1)

Seq: 283 a.a.

Struc: 252 a.a.

Enzyme reactions

• Enzyme class: E.C.2.1.1.56 - mRNA (guanine-N(7))-methyltransferase.
• Reaction: a 5'-end (5'-triphosphoguanosine)-ribonucleoside in mRNA + S-adenosyl-L- methionine = a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-ribonucleoside in mRNA + S-adenosyl-L-homocysteine

5'-end (5'-triphosphoguanosine)-ribonucleoside in mRNA + S-adenosyl-L- methionine = 5'-end (N(7)-methyl 5'-triphosphoguanosine)-ribonucleoside in mRNA + S-adenosyl-L-homocysteine (Bound ligand (Het Group name = SA8) matches with 51.43% similarity)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1074/jbc.M501073200

J Biol Chem 280:20404-20412 (2005)

PubMed id: 15760890

Encephalitozoon cuniculi mRNA cap (guanine N-7) methyltransferase: methyl acceptor specificity, inhibition BY S-adenosylmethionine analogs, and structure-guided mutational analysis.

S.Hausmann, S.Zheng, C.Fabrega, S.W.Schneller, C.D.Lima, S.Shuman.

ABSTRACT

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.

Selected figure(s)

Figure 4.
FIG. 4. Chemical structures of AdoMet, AdoHcy, and analogs sinefungin, aza-AdoMet, and carbocyclic aza-AdoMet.

Figure 8.
FIG. 8. Structures of Ecm1 and the active site. A, stereo view of the structure of Ecm1 in complex with aza-AdoMet. B, a 2.2-Å simulated annealing omit map is shown contoured at 1.0 covering the aza-AdoMet ligand. C, stereo view of the Ecm1 structure (Protein Data Bank accession code 1RI2 [PDB] ) in complex with the GTP portion of the m7GpppG cap analog. Potential hydrogen-bonding interactions are shown by dashed lines; waters are rendered as red spheres. Amino acid residues are labeled and shown in stick representation. aza-AdoMet and GTP are shown in stick representation. The figure was generated with Pymol software (W. L. DeLano, www.pymol.org).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 20404-20412) copyright 2005.

Figures were selected by an automated process.