Characterization of SIP428: a NAD+-Dependent Deacetylase Enzyme, in Abiotic Stress.

SABP2-interacting protein 428(SIP428) is a SIR2-type deacetylase, also called sirtuins. The SIP428 proteins belong to a family of NAD+-dependent deacetylase enzyme that was identified in tobacco. SABP2 is an important methyl esterase enzyme that catalyzes the conversion of methyl salicylic acid (MeSA) into salicylic acid (SA) during the pathogenic challenge. Accumulation of SA induces systemic acquired resistance (SAR), a broad-spectrum defense mechanism in other uninfected distal parts of the plant. Sirtuins play diverse roles in DNA repair, apoptosis, and stress responses. Cellular proteins are known to undergo posttranslational modifications such as methylation, phosphorylation, and ubiquitination. A more recent addition to the list is acetylation. Protein acetylation is a reversible modification that plays role in regulating transcription, activation, and deactivation of certain pathways by transferring acetyl group to lysine residues. This change neutralizes the positive charge of the amino group thereby affecting the biological function of the affected proteins. Preliminary research has shown that SIP428 is a non-histone deacetylase. To understand better about the role of SIP-428 in plant physiology and how it plays a vital role in SABP2 signaling pathway we will be using transgenic tobacco plant in which the expression of SIP 428 has been silenced/knocked down.