title: Giardia duodenalis GlSir2.2, homolog of SIRT1, is a nuclear-located and NAD(+)-dependent deacethylase.
abstract: Sir2 family proteins are highly conserved and catalyze Nicotinamide Adenine Dinucleotide (NAD(+))-dependent protein deacetylation reaction that regulates multiple cellular processes. Little is known about Sir2 family proteins in Giardia. In this research, Sir2 homologs of Giardia were Phylogenetically analyzed. GL50803_10707 (GlSIR2.2) showed strong homology to SIRT1 and was the only parasite SIRT1 homolog being reported to date. Recombinant GlSIR2.2 (rGlSIR2.2) was expressed and purified. The renaturied recombinant protein showed a typical NAD-dependent protein deacetylase activity that could be inhibited by nicotinamide, with IC50 of 4.47 mM rGlSIR2.2 displayed deacetylase activity under varied NAD(+), with Km, kcat and kcat/Km values of 31.71 μM, 1.4 × 10(-3) s(-1), and 4.42 × 10(-5) μM(-1) s(-1). Similarly, the steady-state kinetic parameters with varied ZMAL, yielded Km, kcat and kcat/Km values of 96.89 μM, 4.7 × 10(-3) s(-1), and 4.85 × 10(-5) μM(-1) s(-1). Anti-rGlSIR2.2 serum was used to probe subcellular localization of GlSIR2.2 and strong staining was found predominantly in the nucleus. So we demonstrated that GlSIR2.2 was a SIRT1-like, nuclear-located, NAD(+)-dependent deacetylase. This is the first report of deacetylase activity of Sir2 family protein in Giardia.
authors.affiliation: Medical School, Dalian University, Dalian, 116622, PR China; Microfluidic Research Institute, Dalian University, Dalian, 116622, PR China. Electronic address: yunhua1977@126.com.
authors.forename: Yun-Hua
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Environmental and Chemical Engineering School, Dalian University, Dalian, 116622, PR China; Microfluidic Research Institute, Dalian University, Dalian, 116622, PR China.
authors.forename: Guo-Xia
authors.initials: GX
authors.lastname: Zheng
authors.affiliation: Medical School, Dalian University, Dalian, 116622, PR China; Microfluidic Research Institute, Dalian University, Dalian, 116622, PR China.
authors.forename: Ya-Jie
authors.initials: YJ
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D001549:Benzamides / Q000494:pharmacology; D002467:Cell Nucleus / Q000201:enzymology*; D019084:Fluorescent Antibody Technique, Indirect; D016829:Giardia lamblia / Q000145:classification / Q000201:enzymology* / Q000648:ultrastructure; D056545:Group III Histone Deacetylases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D020128:Inhibitory Concentration 50; D009281:Naphthalenes / Q000494:pharmacology; D009284:Naphthols / Q000494:pharmacology; D009536:Niacinamide / Q000494:pharmacology; D010802:Phylogeny; D011753:Pyrones / Q000494:pharmacology; D016415:Sequence Alignment; D037761:Sirtuins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D001549:Benzamides; D009281:Naphthalenes; D009284:Naphthols; D011753:Pyrones; C439060:sirtinol; D009536:Niacinamide; C444426:splitomicin; D056545:Group III Histone Deacetylases; D037761:Sirtuins
keywords: Deacetylase; Giardia duodenalis; Nicotinamide adenine dinucleotide; Silent information regulator proteins