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2.1.1.297: peptide chain release factor N5-glutamine methyltransferase

This is an abbreviated version!
For detailed information about peptide chain release factor N5-glutamine methyltransferase, go to the full flat file.

Word Map on EC 2.1.1.297

Reaction

S-adenosyl-L-methionine
+
[peptide chain release factor 1 or 2]-L-glutamine
=
S-adenosyl-L-homocysteine
 +
[peptide chain release factor 1 or 2]-N5-methyl-L-glutamine

Synonyms

HemK, HemK methyltransferase family member 2, isoform CRA_c, Hemk1, Hemk2, N5-glutamine methyltransferase, N5-glutamine MTase, N5-glutamine S-adenosyl-L-methionine dependent methyltransferase, N6AMT1, PrmC, PrmC/HemK, release factor glutamine methyltransferase, TM0488

ECTree

     2 Transferases
         2.1 Transferring one-carbon groups
             2.1.1 Methyltransferases
                2.1.1.297 peptide chain release factor N5-glutamine methyltransferase

Crystallization

Crystallization on EC 2.1.1.297 - peptide chain release factor N5-glutamine methyltransferase

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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
analysis of the crystal structure of the HemK N-terminal domain, PDB ID 1T43
molecular replacement based on the data of Thermotoga maritima enzyme, in complex with the methyl-donor product S-adenosyl-L-homocysteine. Enzyme HemK contains two domains: a putative substrate binding domain at the N-terminus consisting of a five helix bundle and a seven-stranded catalytic domain at the C-terminus that harbors the binding site for S-adenosyl-L-homocysteine. The two domains are linked by a beta-hairpin. The apparent hinge mobility of the two domains may reflect functional importance during the reaction cycle
crystallized in the presence of S-adenosylmethionine at 223°C using ammonium sulfate as the precipitant. X-ray diffraction data are collected to 2.5 A resolution from a native crystal. The crystal is orthorhombic, belonging to the space group I222 (or I2(1)2(1)2(1)), with unit-cell parameters of a = 104.24, b = 118.73, and c = 146.62 A. Two (or three) monomers of recombinant HemK are likely to be present in the crystallographic asymmetric unit
to 2.2 A resolution. The C-terminal domain of PrmC adopts the canonical S-adenosyl-L-methionine-dependent methyltransferase fold and shares structural similarity with the nucleotide N-methyltransferases in the active site, including use of a conserved (D/N)PPY motif to select and position the glutamine substrate. Residues of the PrmC 197NPPY200 motif form hydrogen bonds that position the planar Gln side chain such that the lone-pair electrons on the nitrogen nucleophile are oriented toward the methyl group of S-adenosyl-Lmethionine. In the product complex, the methyl group remains pointing toward the sulfur, consistent with either an sp3-hybridized, positively charged Gln nitrogen, or a neutral sp2-hybridized nitrogen in a strained conformation. Due to steric overlap within the active site, proton loss and formation of the neutral planar methylamide product are likely to occur during or after product release