PDBsum entry 1hq2

Transferase

PDB id: 1hq2

Contents

Protein chain

158 a.a. *

Ligands

ACT ×4

APC

PH2

Metals

_MG ×2

_CL

Waters ×333

* Residue conservation analysis

PDB id:

1hq2

Name:

Transferase

Title:

Crystal structure of a ternary complex of e.Coli hppk(r82a) with mgampcpp and 6-hydroxymethyl-7,8-dihydropterin at 1.25 angstrom resolution

Structure:

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase. Chain: a. Synonym: 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase, hppk. Engineered: yes. Mutation: yes

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.25Å R-factor: 0.134 R-free: 0.172

Authors:

J.Blaszczyk,X.Ji

Key ref:

J.Blaszczyk et al. (2003). Dynamic roles of arginine residues 82 and 92 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: crystallographic studies. Biochemistry, 42, 1573-1580. PubMed id: 12578370 DOI: 10.1021/bi0267994

Date:

13-Dec-00 Release date: 15-Apr-03

Protein chain

P26281  (HPPK_ECOLI) -  2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase from Escherichia coli (strain K12)

Seq: 159 a.a.

Struc: 158 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.2.7.6.3 - 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase.
• Pathway: Folate Biosynthesis (late stages)
• Reaction: 6-hydroxymethyl-7,8-dihydropterin + ATP = (7,8-dihydropterin-6-yl)methyl diphosphate + AMP + H⁺

6-hydroxymethyl-7,8-dihydropterin + ATP = (7,8-dihydropterin-6-yl)methyl diphosphate + AMP (Bound ligand (Het Group name = APC) matches with 68.75% similarity) + H(+)

• Cofactor: Mg(2+)

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

Added reference

DOI no: 10.1021/bi0267994

Biochemistry 42:1573-1580 (2003)

PubMed id: 12578370

Dynamic roles of arginine residues 82 and 92 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: crystallographic studies.

J.Blaszczyk, Y.Li, G.Shi, H.Yan, X.Ji.

ABSTRACT

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate biosynthetic pathway. Arginine residues 82 and 92, strictly conserved in 35 HPPK sequences, play dynamic roles in the catalytic cycle of the enzyme. At 0.89-A resolution, two distinct conformations are observed for each of the two residues in the crystal structure of the wild-type HPPK in complex with two HP variants, two Mg(2+) ions, and an ATP analogue. Structural information suggests that R92 first binds to the alpha-phosphate group of ATP and then shifts to interact with the beta-phosphate as R82, which initially does not bind to ATP, moves in and binds to alpha-phosphate when the pyrophosphoryl transfer is about to occur. The dynamic roles of R82 and R92 are further elucidated by five more crystal structures of two mutant proteins, R82A and R92A, with and without bound ligands. Two oxidized forms of HP are observed with an occupancy ratio of 0.50:0.50 in the 0.89-A structure. The oxidation of HP has significant impact on its binding to the protein as well as the conformation of nearby residue W89.