Characterization of antizyme function in a yeast complementation system

Abstract

Ornithine decarboxylase (ODC) is an important enzyme in the synthesis of polyamines. Polyamines are charged organic molecules that are essential for cell growth. Antizyme is an enzyme that aids in the regulation of polyamine levels within the cell by targeting ODC for degradation. A yeast strain has been established that involves the complementation of a null mutant endogenous ODC gene with expression of human ODC. The ODC gene was constitutively expressed while antizyme expression was controlled by galactose induction. In the presence of galactose, induced antizyme expression resulted in eventual cell death due to ODC degradation and depletion of polyamines. Using this system we will transform the strain with a yeast cDNA library controlled by a GAL promoter. We will screen for overexpressed yeast proteins that may inhibit antizyme function. The inhibition of antizyme will allow the yeast to grow since ODC will no longer be degraded. Identifying yeast genes that functionally interact with antizyme will lead to an increased understanding of the activity and function of antizyme in polyamine synthesis. The ability to understand the function and mechanism of antizyme’s ability to target ODC for degradation could help in the control of cell growth. Polyamine regulation is highly conserved in all organisms thus the study of AZ function in yeast can have direct applications to higher vertebrates. Supported by BRIN/INBRE Grant # P20 RR016457 from the NIH.