PDBsum entry 2azt

Transferase

PDB id: 2azt

Contents

Protein chain

276 a.a. *

Ligands

BME ×5

CIT ×2

Metals

_CL

Waters ×40

* Residue conservation analysis

PDB id:

2azt

Name:

Transferase

Title:

Crystal structure of h176n mutant of human glycine n-methyltransferase

Structure:

Glycine n-methyltransferase. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: gnmt. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Tetramer (from PDB file)

Resolution:

2.70Å R-factor: 0.239 R-free: 0.282

Authors:

Z.Luka,S.Pakhomova,Y.Luka,M.E.Newcomer,C.Wagner

Key ref:

Z.Luka et al. (2007). Destabilization of human glycine N-methyltransferase by H176N mutation. Protein Sci, 16, 1957-1964. PubMed id: 17660255 DOI: 10.1110/ps.072921507

Date:

12-Sep-05 Release date: 26-Sep-06

Protein chains

Q14749  (GNMT_HUMAN) -  Glycine N-methyltransferase from Homo sapiens

Seq: 295 a.a.

Struc: 276 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.2.1.1.20 - glycine N-methyltransferase.
• Reaction: glycine + S-adenosyl-L-methionine = sarcosine + S-adenosyl-L-homocysteine + H⁺

glycine (Bound ligand (Het Group name = BME) matches with 50.00% similarity) + S-adenosyl-L-methionine = sarcosine + S-adenosyl-L-homocysteine + H(+)

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

reference

DOI no: 10.1110/ps.072921507

Protein Sci 16:1957-1964 (2007)

PubMed id: 17660255

Destabilization of human glycine N-methyltransferase by H176N mutation.

Z.Luka, S.Pakhomova, Y.Luka, M.E.Newcomer, C.Wagner.

ABSTRACT

In the presence of moderate (2-4 M) urea concentrations the tetrameric enzyme, glycine N-methyltransferase (GNMT), dissociates into compact monomers. Higher concentrations of urea (7-8 M) promote complete denaturation of the enzyme. We report here that the H176N mutation in this enzyme, found in humans with hypermethioninaemia, significantly decreases stability of the tetramer, although H176 is located far from the intersubunit contact areas. Dissociation of the tetramer to compact monomers and unfolding of compact monomers of the mutant protein were detected by circular dichroism, quenching of fluorescence emission, size-exclusion chromatography, and enzyme activity. The values of apparent free energy of dissociation of tetramer and of unfolding of compact monomers for the H176N mutant (27.7 and 4.2 kcal/mol, respectively) are lower than those of wild-type protein (37.5 and 6.2 kcal/mol). A 2.7 A resolution structure of the mutant protein revealed no significant difference in the conformation of the protein near the mutated residue.

Selected figure(s)

Figure 5.
Figure 5. Study of unfolding of wild-type and H176N mutant GNMTs by

Figure 7.
Figure 7. Histidine and asparagine 176 interactions with neighboring

The above figures are reprinted by permission from the Protein Society: Protein Sci (2007, 16, 1957-1964) copyright 2007.

Figures were selected by an automated process.