Roles of the plant SIRTUIN deacetylases in plant immunity

SIRTUIN proteins are largely NAD+-dependent protein deacetylases that couple lysine deacetylation with NAD+ hydrolysis to yield O-acetyl-ADP-ribose (OAADPR), nicotinamide, and deacetylated lysine. SIRTUINs, initially identified in yeast in the regulation of gene silencing, have now been identified in all kingdoms. SIRTUINs have been implicated in regulating a wide range of biological processes through chromatin remodeling and epigenetic regulation. The product OAADPR has also been found to functions in chromatin remodeling. Arabidopsis has two SIRTUIN-encoding genes, SRT1 and SRT2, but their cellular functions remain largely unclear. Our preliminary study suggests that Arabidopsis SRT and OAADPR might play important roles in controlling plant defense responses, possibly through epigenetic modifications.

The aim of the study is to determine the functions of both the Arabidopsis SRT proteins and the unique metabolite OAADPR in cellular processes, particularly in defense responses. We will analyze the role of SRTs in mediating histone modification (deacetylation of lysines in histones), histone variant deposition, and plant defense responses. Genetic, biochemical, and molecular methods will be employed to characterize the two Arabidopsis SRTs through manipulation of their activity and identification of their substrates and effectors in order to determine the link between the SIRTUIN pathway and plant immunity.