Crystal structure of 1-aminocyclopropane-1-carboxylate deaminase from Hansenula saturnus.
The pyridoxal 5'-phosphate (PLP)-dependent enzyme 1-aminocyclopropane-1-carboxylate deaminase (ACCD) catalyzes a reaction that involves a ring opening of cyclopropanoid amino acid, yielding alpha-ketobutyrate and ammonia. Unlike other PLP-dependent enzymes, this enzyme has no alpha-hydrogen atom in the substrate. Thus, a unique mechanism for the bond cleavage is expected. The crystal structure of ACCD from Hansenula saturnus has been determined at 2.0 A resolution by the multiple wavelength anomalous diffraction method using mercury atoms as anomalous scatterers. The model was built on the electron density map, which was obtained by the density averaging of multiple crystal forms. The final model was refined to an R-factor of 22.5% and an R(free)-factor of 26.8%. The ACCD folds into two domains, each of which has an open twisted alpha/beta structure similar to the beta-subunit of tryptophan synthase. However, in ACCD, unlike in other members of the beta family of PLP-dependent enzymes, PLP is buried deep in the molecule. The structure provides the first view of the catalytic center of the cyclopropane ring opening.
Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
M
M
Yao
T
T
Ose
H
H
Sugimoto
A
A
Horiuchi
A
A
Nakagawa
S
S
Wakatsuki
D
D
Yokoi
T
T
Murakami
M
M
Honma
I
I
Tanaka
D000595:Amino Acid Sequence; D019755:Carbon-Carbon Lyases / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010843:Pichia / Q000201:enzymology*; D011487:Protein Conformation; D011732:Pyridoxal Phosphate / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D011732:Pyridoxal Phosphate; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases