Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/60783
標題: Functional Role of Dimerization of Human Peptidylarginine Deiminase 4 (PAD4)
作者: Liu, Yi-Liang
Chiang, Yu-Hsiu
Liu, Guang-Yaw
Hung, Hui-Chih
關鍵字: rheumatoid-arthritis
developmentally immature
arginine methylation
histone deimination
multiple-sclerosis
molecular-cloning
gene
organization
structural basis
human skin
protein
摘要: Peptidylarginine deiminase 4 (PAD4) is a homodimeric enzyme that catalyzes Ca(2+)-dependent protein citrullination, which results in the conversion of arginine to citrulline. This paper demonstrates the functional role of dimerization in the regulation of PAD4 activity. To address this question, we created a series of dimer interface mutants of PAD4. The residues Arg8, Tyr237, Asp273, Glu281, Tyr435, Arg544 and Asp547, which are located at the dimer interface, were mutated to disturb the dimer organization of PAD4. Sedimentation velocity experiments were performed to investigate the changes in the quaternary structures and the dissociation constants (K(d)) between wild-type and mutant PAD4 monomers and dimers. The kinetic data indicated that disrupting the dimer interface of the enzyme decreases its enzymatic activity and calcium-binding cooperativity. The K(d) values of some PAD4 mutants were much higher than that of the wild-type (WT) protein (0.45 mu M) and were concomitant with lower k(cat) values than that of WT (13.4 s(-1)). The K(d) values of the monomeric PAD4 mutants ranged from 16.8 to 45.6 mu M, and the k(cat) values of the monomeric mutants ranged from 3.3 to 7.3 s(-1). The k(cat) values of these interface mutants decreased as the K(d) values increased, which suggests that the dissociation of dimers to monomers considerably influences the activity of the enzyme. Although dissociation of the enzyme reduces the activity of the enzyme, monomeric PAD4 is still active but does not display cooperative calcium binding. The ionic interaction between Arg8 and Asp547 and the Tyr435-mediated hydrophobic interaction are determinants of PAD4 dimer formation.
URI: http://hdl.handle.net/11455/60783
ISSN: 1932-6203
Appears in Collections:基因體暨生物資訊學研究所

文件中的檔案:

取得全文請前往華藝線上圖書館



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.