Inactive S298R disassembles the dodecameric L-aspartate 4-decarboxylase into dimers.
L-Aspartate 4-decarboxylase catalyzes the conversion of aspartate to alanine and CO(2). The wild-type enzyme was observed as dodecamers at pH 5.0. The mutation of Ser298 into Arg resulted in an almost complete loss of the enzyme activity, and caused regional structural distortion and defects in the enzyme assembly, as shown in circular dichroism spectra and gel filtration profiles. Mutating Tyr207 and Pro257 into His also resulted in inactivation of the enzyme, but did not affect the overall structure. Computer modeling suggests that Ser298 is located on the surface, and its mutation may result in enzyme disassembly, whereas Tyr207 and Pro257 are near the active site, and their mutations may cause local structure perturbation.
Wang
Nai-Chen
NC
Department of Agricultural Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
Ko
Tzu-Ping
TP
Lee
Chia-Yin
CY
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001120:Arginine / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D003198:Computer Simulation; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D011549:Pseudomonas / Q000201:enzymology*; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D012694:Serine / Q000737:chemistry / Q000235:genetics
D001426:Bacterial Proteins; D012694:Serine; D011732:Pyridoxal Phosphate; D001120:Arginine; D002262:Carboxy-Lyases; C019747:aspartate 4-decarboxylase