Functional Roles of the Dimer-Interface Residues in Human Ornithine Decarboxylase

doi:10.1371/journal.pone.0104865

中山醫學大學機構典藏 CSMUIR > 醫學院 > 免疫學研究所 > 期刊論文 > Item 310902500/11698

Please use this identifier to cite or link to this item: https://ir.csmu.edu.tw:8080/ir/handle/310902500/11698

Title:	Functional Roles of the Dimer-Interface Residues in Human Ornithine Decarboxylase
Authors:	Lee, Chien-Yun Liu, Yi-Liang Lin, Chih-Li Liu, Guang-Yaw Hung, Hui-Chih
Contributors:	中山醫學大學
Date:	2014
Issue Date:	2015-07-28T04:06:28Z (UTC)
ISSN:	1932-6203
Abstract:	Ornithine decarboxylase (ODC) catalyzes the decarboxylation of ornithine to putrescine and is the rate-limiting enzyme in the polyamine biosynthesis pathway. ODC is a dimeric enzyme, and the active sites of this enzyme reside at the dimer interface. Once the enzyme dissociates, the enzyme activity is lost. In this paper, we investigated the roles of amino acid residues at the dimer interface regarding the dimerization, protein stability and/or enzyme activity of ODC. A multiple sequence alignment of ODC and its homologous protein antizyme inhibitor revealed that 5 of 9 residues (residues 165, 277, 331, 332 and 389) are divergent, whereas 4 (134, 169, 294 and 322) are conserved. Analytical ultracentrifugation analysis suggested that some dimer-interface amino acid residues contribute to formation of the dimer of ODC and that this dimerization results from the cooperativity of these interface residues. The quaternary structure of the sextuple mutant Y331S/Y389D/R277S/D332E/V322D/D134A was changed to a monomer rather than a dimer, and the Kd value of the mutant was 52.8 µM, which is over 500-fold greater than that of the wild-type ODC (ODC_WT). In addition, most interface mutants showed low but detectable or negligible enzyme activity. Therefore, the protein stability of these interface mutants was measured by differential scanning calorimetry. These results indicate that these dimer-interface residues are important for dimer formation and, as a consequence, are critical for enzyme catalysis.
URI:	https://ir.csmu.edu.tw:8080/ir/handle/310902500/11698 http://dx.doi.org/10.1371/journal.pone.0104865
Relation:	PLoS ONE 9(8): e104865
Appears in Collections:	[免疫學研究所] 期刊論文

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