Crystal structure of an ATP-dependent carboxylase, dethiobiotin synthetase, at 1.65 A resolution.
BACKGROUND
In Escherichia coli, the enzymes of the biotin biosynthesis pathway are encoded by the bio operon. One of these enzymes, ATP-dependent dethiobiotin synthetase, catalyzes the carboxylation of 7,8-diaminopelargonic acid leading to the formation of the ureido ring of biotin. The enzyme belongs to the class of ATP-dependent carboxylases and we present here the first crystal structure determined for this class of enzyme.


RESULTS
We have determined the crystal structure of homodimeric dethiobiotin synthetase to 1.65 A resolution. The subunit consists of a seven-stranded parallel beta-sheet, surrounded by alpha-helices. The sheet contains the classical mononucleotide-binding motif with a fingerprint peptide Gly-X-X-X-X-X-Gly-Lys-Thr. The mononucleotide binding part of the structure is very similar to the GTP-binding protein H-ras-p21 and thus all GTP-binding proteins. A comparison reveals that some of the residues, which in H-ras-p21 interact with the nucleotide and the metal ion, are conserved in the synthetase.


CONCLUSIONS
The three-dimensional structure of dethiobiotin synthetase has revealed that ATP-dependent carboxylases contain the classical mononucleotide-binding fold. Considerable similarities to the structure of the GTP-binding protein H-ras-p21 were found, indicating that both proteins might have evolved from a common ancestral mononucleotide-binding fold.
Huang
W
W
Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala.
Lindqvist
Y
Y
Schneider
G
G
Gibson
K J
KJ
Flint
D
D
Lorimer
G
G
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D001710:Biotin / Q000031:analogs & derivatives* / Q000096:biosynthesis; D002245:Carbon Dioxide / Q000378:metabolism; D019731:Carbon-Nitrogen Ligases; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D008025:Ligases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry
D011994:Recombinant Proteins; D002245:Carbon Dioxide; D001710:Biotin; C004749:desthiobiotin; D000255:Adenosine Triphosphate; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C020024:dethiobiotin synthetase