TY - JOUR
T1 - Structure, Assembly, and Mechanism of a PLP-Dependent Dodecameric l-Aspartate β-Decarboxylase
AU - Chen, Hui Ju
AU - Ko, Tzu Ping
AU - Lee, Chia Yin
AU - Wang, Nai Chen
AU - Wang, Andrew H.J.
N1 - Funding Information:
We thank National Synchrotron Radiation Research Center of Taiwan, Photon Factory of Japan, and Advanced Light Source of UC Berkeley for beam time allocations. We also thank Shu-Chuan Jao and Hui-Chuan Chang for their advice in the ITC and AUC experiments. This work was supported by grants from the National Science Council of Taiwan, ROC (NSC94-2313-B-002-049 and NSC95-2811-B-002-055 to C.Y.L. and NSC-95-3112-B-011-015-Y to A.H.J.W.).
PY - 2009/4/15
Y1 - 2009/4/15
N2 - The type-I PLP enzyme l-aspartate β-decarboxylase converts aspartate to alanine and CO2. Similar to the homodimeric aminotransferases, its protein subunit comprises a large and a small domain, of 410 and 120 residues, respectively. The crystal structure reveals a dodecamer made of six identical dimers arranged in a truncated tetrahedron whose assembly involves tetramer and hexamer as intermediates. The additional helical motifs I and II participate in the oligomer formation. Triple mutations of S67R/Y68R/M69R or S67E/Y68E/M69E in motif I produced an inactive dimer. The PLP is bound covalently to Lys315 in the active site, while its phosphate group interacts with a neighboring Tyr134. Removal of the bulky side chain of Arg37, which overhangs the PLP group, improved the substrate affinity. Mutations in flexible regions produced the more active K17A and the completely inactive R487A. The structure also suggests that substrate binding triggers conformational changes essential for catalyzing the reaction.
AB - The type-I PLP enzyme l-aspartate β-decarboxylase converts aspartate to alanine and CO2. Similar to the homodimeric aminotransferases, its protein subunit comprises a large and a small domain, of 410 and 120 residues, respectively. The crystal structure reveals a dodecamer made of six identical dimers arranged in a truncated tetrahedron whose assembly involves tetramer and hexamer as intermediates. The additional helical motifs I and II participate in the oligomer formation. Triple mutations of S67R/Y68R/M69R or S67E/Y68E/M69E in motif I produced an inactive dimer. The PLP is bound covalently to Lys315 in the active site, while its phosphate group interacts with a neighboring Tyr134. Removal of the bulky side chain of Arg37, which overhangs the PLP group, improved the substrate affinity. Mutations in flexible regions produced the more active K17A and the completely inactive R487A. The structure also suggests that substrate binding triggers conformational changes essential for catalyzing the reaction.
KW - PROTEINS
UR - http://www.scopus.com/inward/record.url?scp=64049088222&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=64049088222&partnerID=8YFLogxK
U2 - 10.1016/j.str.2009.02.013
DO - 10.1016/j.str.2009.02.013
M3 - Article
C2 - 19368885
AN - SCOPUS:64049088222
VL - 17
SP - 517
EP - 529
JO - Structure with Folding & design
JF - Structure with Folding & design
SN - 0969-2126
IS - 4
ER -