 |
PDBsum entry 1qgo
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Metal binding protein
|
PDB id
|
|
|
|
1qgo
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Common chelatase design in the branched tetrapyrrole pathways of heme and anaerobic cobalamin synthesis.
|
|
|
Authors
|
|
H.L.Schubert,
E.Raux,
K.S.Wilson,
M.J.Warren.
|
|
|
Ref.
|
|
Biochemistry, 1999,
38,
10660-10669.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Prosthetic groups such as heme, chlorophyll, and cobalamin (vitamin B(12)) are
characterized by their branched biosynthetic pathway and unique metal insertion
steps. The metal ion chelatases can be broadly classed either as single-subunit
ATP-independent enzymes, such as the anaerobic cobalt chelatase and the
protoporphyrin IX (PPIX) ferrochelatase, or as heterotrimeric, ATP-dependent
enzymes, such as the Mg chelatase involved in chlorophyll biosynthesis. The
X-ray structure of the anaerobic cobalt chelatase from Salmonella typhimurium,
CbiK, has been solved to 2.4 A resolution. Despite a lack of significant amino
acid sequence similarity, the protein structure is homologous to that of
Bacillus subtilis PPIX ferrochelatase. Both enzymes contain a histidine residue
previously identified as the metal ion ligand, but CbiK contains a second
histidine in place of the glutamic acid residue identified as a general base in
PPIX ferrochelatase. Site-directed mutagenesis has confirmed a role for this
histidine and a nearby glutamic acid in cobalt binding, modulating metal ion
specificity as well as catalytic efficiency. Contrary to the predicted
protoporphyrin binding site in PPIX ferrochelatase, the precorrin-2 binding site
in CbiK is clearly defined within a large horizontal cleft between the N- and
C-terminal domains. The structural similarity has implications for the
understanding of the evolution of this branched biosynthetic pathway.
|
|
|
Secondary reference #1
|
|
|
Title
|
|
A role for salmonella typhimurium cbik in cobalamin (vitamin b12) and siroheme biosynthesis.
|
|
|
Authors
|
|
E.Raux,
C.Thermes,
P.Heathcote,
A.Rambach,
M.J.Warren.
|
|
|
Ref.
|
|
J Bacteriol, 1997,
179,
3202-3212.
|
|
|
PubMed id
|
|
|
|
|
|
|
|
|
|
|
|
|
