Critical factors determining dimerization of human antizyme inhibitor.

doi:10.1074/jbc.M109.007807

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 310902500/11709

Please use this identifier to cite or link to this item: https://ir.csmu.edu.tw:8080/ir/handle/310902500/11709

Title:	Critical factors determining dimerization of human antizyme inhibitor.
Authors:	Su, KL Liao, YF Hung, HC Liu, GY
Contributors:	中山醫學大學
Date:	2009
Issue Date:	2015-07-28T04:41:23Z (UTC)
ISSN:	0021-9258
Abstract:	Ornithine decarboxylase (ODC) is the first enzyme involved in polyamine biosynthesis, and it catalyzes the decarboxylation of ornithine to putrescine. ODC is a dimeric enzyme, whereas antizyme inhibitor (AZI), a positive regulator of ODC that is homologous to ODC, exists predominantly as a monomer and lacks decarboxylase activity. The goal of this paper was to identify the essential amino acid residues that determine the dimerization of AZI. The nonconserved amino acid residues in the putative dimer interface of AZI (Ser-277, Ser-331, Glu-332, and Asp-389) were substituted with the corresponding residues in the putative dimer interface of ODC (Arg-277, Tyr-331, Asp-332, and Tyr-389, respectively). Analytical ultracentrifugation analysis was used to determine the size distribution of these AZI mutants. The size-distribution analysis data suggest that residue 331 may play a major role in the dimerization of AZI. Mutating Ser-331 to Tyr in AZI (AZI-S331Y) caused a shift from a monomer configuration to a dimer. Furthermore, in comparison with the single mutant AZI-S331Y, the AZI-S331Y/D389Y double mutant displayed a further reduction in the monomer-dimer K(d), suggesting that residue 389 is also crucial for AZI dimerization. Analysis of the triple mutant AZI-S331Y/D389Y/S277R showed that it formed a stable dimer (K(d) value = 1.3 microm). Finally, a quadruple mutant, S331Y/D389Y/S277R/E332D, behaved as a dimer with a K(d) value of approximately 0.1 microm, which is very close to that of the human ODC enzyme. The quadruple mutant, although forming a dimer, could still be disrupted by antizyme (AZ), further forming a heterodimer, and it could rescue the AZ-inhibited ODC activity, suggesting that the AZ-binding ability of the AZI dimer was retained.
URI:	https://ir.csmu.edu.tw:8080/ir/handle/310902500/11709 http://dx.doi.org/10.1074/jbc.M109.007807
Relation:	J Biol Chem. 2009 Sep 25;284(39):26768-77.
Appears in Collections:	[免疫學研究所] 期刊論文

Files in This Item:

File	Description	Size	Format
index.html	期刊論文	0Kb	HTML	330	View/Open

View Licence

Loading...