PDBsum entry 3hcc

Transferase

PDB id: 3hcc

Contents

Protein chain

259 a.a. *

Ligands

LT3 ×2

SAH ×2

Waters ×269

* Residue conservation analysis

PDB id:

3hcc

Name:

Transferase

Title:

Crystal structure of hpnmt in complex with anti-9-amino-5- (trifluromethyl) benzonorbornene and adohcy

Structure:

Phenylethanolamine n-methyltransferase. Chain: a, b. Synonym: pnmtase, noradrenaline n-methyltransferase. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: pnmt, pent. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.30Å R-factor: 0.208 R-free: 0.240

Authors:

N.Drinkwater,J.L.Martin,C.L.Gee,M.Puri

Key ref:

N.Drinkwater et al. (2009). Molecular recognition of physiological substrate noradrenaline by the adrenaline-synthesizing enzyme PNMT and factors influencing its methyltransferase activity. Biochem J, 422, 463-471. PubMed id: 19570037

Date:

06-May-09 Release date: 25-Aug-09

Protein chains

P11086  (PNMT_HUMAN) -  Phenylethanolamine N-methyltransferase from Homo sapiens

Seq: 282 a.a.

Struc: 259 a.a.

Enzyme reactions

• Enzyme class: E.C.2.1.1.28 - phenylethanolamine N-methyltransferase.
• Pathway: Dopa Biosynthesis
• Reaction: phenylethanolamine + S-adenosyl-L-methionine = N-methylphenylethanolamine + S-adenosyl-L-homocysteine + H⁺

phenylethanolamine (Bound ligand (Het Group name = LT3) matches with 52.94% similarity) + S-adenosyl-L-methionine = N-methylphenylethanolamine + S-adenosyl-L-homocysteine + H(+) (Bound ligand (Het Group name = SAH) corresponds exactly)

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

reference

Biochem J 422:463-471 (2009)

PubMed id: 19570037

Molecular recognition of physiological substrate noradrenaline by the adrenaline-synthesizing enzyme PNMT and factors influencing its methyltransferase activity.

N.Drinkwater, C.L.Gee, M.Puri, K.R.Criscione, M.J.McLeish, G.L.Grunewald, J.L.Martin.

ABSTRACT

Substrate specificity is critically important for enzyme catalysis. In the adrenaline-synthesizing enzyme PNMT (phenylethanolamine N-methyltransferase), minor changes in substituents can convert substrates into inhibitors. Here we report the crystal structures of six human PNMT complexes, including the first structure of the enzyme in complex with its physiological ligand R-noradrenaline. Determining this structure required rapid soak methods because of the tendency for noradrenaline to oxidize. Comparison of the PNMT-noradrenaline complex with the previously determined PNMT-p-octopamine complex demonstrates that these two substrates form almost equivalent interactions with the enzyme and show that p-octopamine is a valid model substrate for PNMT. The crystal structures illustrate the adaptability of the PNMT substrate binding site in accepting multi-fused ring systems, such as substituted norbornene, as well as noradrenochrome, the oxidation product of noradrenaline. These results explain why only a subset of ligands recognized by PNMT are methylated by the enzyme; bulky substituents dictate the binding orientation of the ligand and can thereby place the acceptor amine too far from the donor methyl group for methylation to occur. We also show how the critical Glu(185) catalytic residue can be replaced by aspartic acid with a loss of only 10-fold in catalytic efficiency. This is because protein backbone movements place the Asp(185) carboxylate almost coincident with the carboxylate of Glu(185). Conversely, replacement of Glu(185) by glutamine reduces catalytic efficiency almost 300-fold, not only because of the loss of charge, but also because the variant residue does not adopt the same conformation as Glu(185).