| Autor: |
Hsieh JY; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Liu YC; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Cheng IT; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Lee CJ; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Wang YH; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Fang YS; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan., Liu YL; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan.; Institute of Biochemistry, Microbiology & Immunology, Chung Shan Medical University, Taichung 40201, Taiwan.; Division of Allergy, Immunology, and Rheumatology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan., Liu GY; Institute of Biochemistry, Microbiology & Immunology, Chung Shan Medical University, Taichung 40201, Taiwan.; Division of Allergy, Immunology, and Rheumatology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan., Hung HC; Department of Life Sciences and Institute of Genomics & Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan.; iEGG & Animal Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan. |
| Abstrakt: |
Antizyme (AZ) is a protein that negatively regulates ornithine decarboxylase (ODC). AZ achieves this inhibition by binding to ODC to produce AZ-ODC heterodimers, abolishing enzyme activity and targeting ODC for degradation by the 26S proteasome. In this study, we focused on the biomolecular interactions between the C-terminal domain of AZ (AZ 95-228 ) and ODC to identify the functional elements of AZ that are essential for binding, inhibiting and degrading ODC, and we also identified the crucial factors governing the differential binding and inhibition ability of AZ isoforms toward ODC. Based on the ODC inhibition and AZ-ODC binding studies, we demonstrated that amino acid residues reside within the α1 helix, β5 and β6 strands, and connecting loop between β6 and α2 (residues 142-178), which is the posterior part of AZ 95-228 , play crucial roles in ODC binding and inhibition. We also identified the essential elements determining the ODC-degradative activity of AZ; amino acid residues within the anterior part of AZ 95-228 (residues 120-145) play crucial roles in AZ-mediated ODC degradation. Finally, we identified the crucial factors that govern the differential binding and inhibition of AZ isoforms toward ODC. Mutagenesis studies of AZ1 and AZ3 and their binding and inhibition revealed that the divergence of amino acid residues 124, 150, 166, 171, and 179 results in the differential abilities of AZ1 and AZ3 in the binding and inhibition of ODC. |
