Function Of NAD～+ Dependent Protein Deacetylase Of Arabidopsis.

The Sir2 (silence information regulator) gene family is an NAD~+ dependent protein deacetylase which is conserved from archabecteria to humans. In yeast, it has been implicated to play roles in gene silencing, genome stability, longevity and metabolism through histone deacetylase activity during calorie restriction. Mammals have seven homologies of Sir2, namely SIRT1 to SIRT7. The SIRT1 gene has been proven to play a pivotal role in the regulation of DNA repair, metabolism, apoptosis and extend life span. AtSIRT1 and AtSIRT2 of Arabidopsis which belong to Sir gene family were studied in this article. Promoters of these two genes were fused to reporter gene to reveal their expression patterns in transgenic plants. Coding sequences of AtSIRT1 and AtSIRT2 were fused with EGFP to indicate their subcellular locations. Results as bellows: AtSIRT1 was located in Mitochondrial as hSIRT4 of human, and maybe take part in respiration and electron transformation chain, AtSIRT2 was located in nucleolus as hSIRT6 of human, maybe play important role in extend lifespan;mutation in AtSIRT1 leaded to cotyledon of plant turn to yellow and caused short life span. Mutation in AtSIRT2 could make the color of leaf turn to purple and accumulate a lot of anthocyanin;Sirtinol, a inhibitor of SIRT which did not cause the same model of the mutation of AtSIRT1 and AtSIRT2 indicated that the mechanism of Sirtinol was different from other organism;the structure of AtSIRT1 and AtSIRT2 were similar to other known Sir2, which indicated that they maybe have the same function;AtSIRT2 was overexpressed and its activity was detected. Through these results, the function of AtSIRT1 and AtSIRT2 were appeared.