PDBsum entry 1ld3

Lyase

PDB id: 1ld3

Contents

Protein chain

309 a.a. *

Metals

_ZN

Waters ×37

* Residue conservation analysis

PDB id:

1ld3

Name:

Lyase

Title:

Crystal structure of b. Subilis ferrochelatase with zn(2+) bound at the active site.

Structure:

Ferrochelatase. Chain: a. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.60Å R-factor: 0.217 R-free: 0.274

Authors:

D.Lecerof,M.N.Fodje,R.A.Leon,U.Olsson,A.Hansson,E.Sigfridsson,U.Ryde, M.Hansson,S.Al-Karadaghi

Key ref:

D.Lecerof et al. (2003). Metal binding to Bacillus subtilis ferrochelatase and interaction between metal sites. J Biol Inorg Chem, 8, 452-458. PubMed id: 12761666 DOI: 10.1007/s00775-002-0436-1

Date:

08-Apr-02 Release date: 20-May-03

Protein chain

P32396  (HEMH_BACSU) -  Coproporphyrin III ferrochelatase from Bacillus subtilis (strain 168)

Seq: 310 a.a.

Struc: 309 a.a.

Enzyme reactions

• Enzyme class: E.C.4.99.1.9 - coproporphyrin ferrochelatase.
• Reaction: Fe-coproporphyrin III + 2 H⁺ = coproporphyrin III + Fe²⁺

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

Key reference

DOI no: 10.1007/s00775-002-0436-1

J Biol Inorg Chem 8:452-458 (2003)

PubMed id: 12761666

Metal binding to Bacillus subtilis ferrochelatase and interaction between metal sites.

D.Lecerof, M.N.Fodje, R.Alvarez León, U.Olsson, A.Hansson, E.Sigfridsson, U.Ryde, M.Hansson, S.Al-Karadaghi.

ABSTRACT

Ferrochelatase, the terminal enzyme in heme biosynthesis, catalyses metal insertion into protoporphyrin IX. The location of the metal binding site with respect to the bound porphyrin substrate and the mode of metal binding are of central importance for understanding the mechanism of porphyrin metallation. In this work we demonstrate that Zn(2+), which is commonly used as substrate in assays of the ferrochelatase reaction, and Cd(2+), an inhibitor of the enzyme, bind to the invariant amino acids His183 and Glu264 and water molecules, all located within the porphyrin binding cleft. On the other hand, Mg(2+), which has been shown to bind close to the surface at 7 A from His183, was largely absent from its site. Activity measurements demonstrate that Mg(2+) has a stimulatory effect on the enzyme, lowering K(M) for Zn(2+) from 55 to 24 micro M. Changing one of the Mg(2+) binding residues, Glu272, to serine abolishes the effect of Mg(2+). It is proposed that prior to metal insertion the metal may form a sitting-atop (SAT) complex with the invariant His-Glu couple and the porphyrin. Metal binding to the Mg(2+) site may stimulate metal release from the protein ligands and its insertion into the porphyrin.