Os04g0271200 is reported as SRT701and SRT702.
- Histone modifications including acetylation, methylation, phosphorylation, ubiquitination and others are shown to play an important role in chromatin function and gene regulation. The homeostatic balance of nucleosomal histone acetylation is maintained by antagonistic action of histone acetyltransferases (HAT) and histone deacetylases (HDAC). Plant HDAC can be grouped into four classes. Among them, three have primary homology to three yeast HDAC groups: RDP3, HDA1 and SIR2.
- The SILENT INFORMATION REGULATOR2 (SIR2) family proteins are NAD +-dependent histone deacetylases. Sir2 is involved in chromatin silencing at the mating-type loci, rDNA, and telomeres in yeast and is associated with lifespan extension in yeast, worms, and flies, but also in a broader range of additional functions.
- The SIR2 family has two members in rice: SRT701 and SRT702.
- The two proteins are likely to have distinct functions, as SRT701 (OsSRT1) is nuclear localized and is shown to be involved in histone H3K9 deacetlyation required for transposon repression in rice, whereas SRT702 is recently shown to be localized in the mitochondria.
- SRT701 RNA interference induced an increase of histone H3K9 (lysine-9 of H3) acetylation and a decrease of H3K9 dimethylation, leading to H2O2 production, DNA fragmentation, cell death, and lesions mimicking plant hypersensitive responses during incompatible interactions with pathogens, whereas overexpression of SRT701 enhanced tolerance to oxidative stress. Transcript microarray analysis revealed that the transcription of many transposons and retrotransposons in addition to genes related to hypersensitive response and/or programmed cell death was activated. Chromatin immunoprecipitation assays showed that SRT701 down-regulation induced histone H3K9 acetylation on the transposable elements and some of the hypersensitive response-related genes, suggesting that these genes may be among the primary targets of deacetylation regulated by SRT701. Rice SIR2-like gene is required for safeguard against genome instability and cell damage to ensure plant cell growth.
- SRT702 resides predominantly at the inner mitochondrial membrane and interacts with a small number of protein complexes mainly involved in energy metabolism and metabolite transport.SRT702 is important in fine-tuning mitochondrial energy metabolism.
- Sir2 silences chromatin, enables DNA repair, and is involved in chromosome fidelity during meiosis (Blander and Guarente 2004). Sir2 promotes longevity by suppressing the formation of toxic extrachromosomal rDNA circles (ERCs) in yeast.
- The Caenorhabditis elegans ortholog sir-2.1 also extends worm lifespan, but by a distinct mechanism.Sir-2.1 requires the worm forkhead protein DAF-16 for lifespan extension .
- While earlier models suggested sir-2.1 might function by down-regulating insulin signaling, more recent findings show that sir-2.1 binds to DAF-16, activating it directly. Moreover, sir-2.1 does not respond to changes in insulin signaling, but, rather, is activated by stress treatments, such as heat shock and oxidative damage 
Proposed functions of yeast Sir2 and of mammalian SIRT1. (a) Yeast Sir2 histone deacetylation and silencing function. Acetyl-CoA-dependent histone acetyltransferases acetylate histones leading to transcriptional activation. The NAD+-dependent deacetylase Sir2 deacetylates histones and creates transcriptional silent chromatin. Nicotinamide is a product of the reaction and is a potent inhibitor of Sir2. OAADPr is a novel metabolite generated during deacetylation and may function in linked cellular pathways. An NAD+ salvage pathway depletes nicotinamide and funnels NAD+ to Sir2. (b) General chemical reaction catalyzed by sirtuins. Human SIRT1 is depicted with several reported acetylated protein targets and the pathways affected.
- Several genes were found to have a specific expression pattern. For instance, HDA710 was more expressed in germinating and young seedlings as well as in stamens, whereas HDA703 was highly expressed in calli and in imbibed seeds. HAD714 and HDA706 were found to be mainly expressed in shoots and leaves, whereas HDA716 showed a strong expression in developing endosperm and germinating seeds. The leaf/shoot specificity of HDA714 is consistent with its protein localization in chloroplasts and mitochondria  , suggesting that this HDAC may play a role in plant specific functions. Three groups of closely related genes (group 1: HDA705, HDA702, HDA709, HDA710 and HDA711; group 2: HDA704 and HDA713; group 3: HDT701 and HDT702) showed a very similar expression pattern with a relatively high level in developing panicles and calli. However, the expression patterns of the two members of the Sir2-like HDACs, SRT701 and SRT702 were found to be different. The two proteins are likely to have distinct functions, as SRT701 (OsSRT1) is nuclear localized and is shown to be involved in histone H3K9 deacetlyation required for transposon repression in rice, whereas SRT702 is recently shown to be localized in the mitochondria. 
- Two genes (HDA703 and HDA710) are induced, while nine others (i.e. HDA701, HDA702, HDA704, HDA705, HDA706, HDA712, HDA714, HDA716, HDT701 and HDT702) are clearly repressed by drought and salt,Two additional genes (HDA709 and SRT702) are induced by drought, but repressed by salt. However, cold treatment seemed to have less impact on rice HDAC gene expression. Abscisic acid (ABA) is the major plant hormone in water stress signaling and regulates water balance and osmotic stress tolerance.
- SRT701 is a widely expressed nuclear protein with higher levels in rapidly dividing tissues.
- It has highest levels in active cell dividing organs/tissues. Down-regulation of SRT701 by RNAi induced lesion mimic cell death and precocious senescence, whereas overexpression showed tolerance to oxidative stress. 
- Cell death was induced in OsSRT1 RNAi plants. Cell death in the SRT701 RNAi plants also resembled hypersensitive response-mediated PCD. Either both types of PCD were induced by SRT701 down-regulation, or different triggers of PCD may be interdependent in plants and the downstream effectors of PCD may be shared among different pathways.
- Western-blot analysis of enriched histone fractions detected a decrease of H3K9 acetylation in overexpression plants (Fig. 6B). The overexpression plants showed no particular visible or morphological phenotype. However, when treated with paraquat (1,1′-dimethyl-4,4′-bipyridylium), an herbicide that induces oxidative stresses in plants, the overexpression plants showed an enhanced tolerance compared to the wild type, as demonstrated by fewer and smaller lesions observed on the overexpression plants than the wild type.
Expression profiles of OsSRT1. A, Northern hybridization detection of OsSRT1 mRNA in different rice tissues or developmental stages. Actin transcripts were detected as controls. B, Nuclear localization of the OsSRT1-GFP fusion. Top, Onion skin cells transfected with OsSRT1-GFP photographed under a confocal microscope at 488 nm (left) and merged with the transmission image (right). Bottom, GFP alone.
Neighbor-joining tree of SIR2-related proteins from eukaryotes. Abbreviations are as follows (in parentheses): Arabidopsis (at), Caenorhabditis elegans (ce), Drosophila melanogaster (dm), Homo sapiens (hs), rice (os), Saccharomyces cerevisiae (sc), Schizosaccharomyces pombe (sp), wheat (ta), and maize (zm). Four subclasses are indicated.
Overexpression of OsSRT1 conferred tolerance to paraquat treatment. A, Northern-blot analysis of OsSRT1 overexpression in different transgenic lines compared to the wild type. The 18S ribosomal RNA levels were revealed as controls. B, Western-blot analysis of enriched histone fractions from pooled samples of the overexpression plants with antibodies against acetylated histone H3K9. C, Comparison of overexpression plants with wild-type ones challenged by 10 μM paraquat. D, Comparison of leaves from overexpression and wild type treated with or without 10 μM paraquat.
Expression analysis of the rice HDAC genes. Upper: A hierarchical cluster display of relative expression levels of the rice HDAC genes in 33 samples representing different organs or tissues at different developmental stages of the Minghui 63 cultivar. 1–5: Calli at different induction stages from cultured embryos. 6: Plumule at 48 h after emergence in the dark. 7: Plumule at 48 h after emergence in the light. 8: Radical at 48 h after emergence in the dark. 9: Radical at 48 h after emergence in the light. 10: 72 h imbibed seed. 11: Embryo and radicle after germination. 12: Seedling leaves and roots at three-leaf stage. 13: Shoots of seedlings with two tillers. 14: Roots of seedlings with two tillers. 15: Stem at day 5 before heading. 16: Stems at heading stage. 17: Leaves from plants at young panicle stage 3. 18: Leaves at young panicle stage 7. 19: Flag leaves at day 5 before heading. 20: Flag leaf at day 14 after heading. 21: Sheaths at young panicle stage 3. 22: Sheaths at young panicle stage 7. 23 : Hulls one day before flowering. 24: Stamens one day before flowering. 25: Young panicle at stage 3. 26: Young panicles at stage 4. 27: Young panicles at stage 5. 28: Panicles at stage 7. 29: Panicles at heading stage. 30: Spikelets, 3 days after pollination. 31: Endosperm, 7 days after pollination. 32: Endosperm, 14 days after pollination. 33: Endosperm, 21 days after pollination. Lower: Expression changes of HDAC genes responding to abiotic stresses including drought, salt and cold in seven-day-old light-grown seedlings. Color bar at the base represents log2 expression values: green, representing low expression; black, medium expression; red, high expression.
- Silent information regulator (Sir) proteins regulate lifespan in multiple model organisms. In yeast, an extra copy of the SIR2 gene extends replicative lifespan by 50%, while deleting Sir2 shortens lifespan.
- Plant histone deacetylases (HDAC)can be grouped into four classes. Among them, three have primary homology to three yeast HDAC groups: RDP3, HDA1 and SIR2.During the last years, HDAC function has been most studied in Arabidopsis.
- The function of SIR2 family HDACs was first been investigated in Arabidopsis. The Arabidopsis genome encodes two SIR2 family HDACs: SRT1 and SRT2. SRT2 resides predominantly at the inner mitochondrial membrane and interacts with a small number of protein complexes mainly involved in energy metabolism and metabolite transport.
- SRT701(OsSRT1), one of the two SIR2-related genes found in rice, has been studied in Huang et al and proved its' function, while SRT702's function has been studied in Arabidopsis.
- Mechanistically, ADP-ribosylation and deacetylation reactions by sirtuins are similar because they cleave NAD in each reaction cycle.
- Mitochondria are central hubs of energy metabolism in plants and animals. In addition to a fine-tuned mitochondria-to-nuclear signaling that regulates transcription of nuclear gene expression, posttranslational modifications of proteins are thought to be essential for the regulation of central metabolic pathways and thus determine the plasticity of plant metabolism. In mammalian mitochondria, the regulation of metabolic functions by posttranslational Lys acetylation of proteins was recently discovered to be of great importance. Lys acetylation can have a strong impact on the biochemical function of proteins as the transfer of the acetyl group to Lys masks the positive charge, which is known to be important in many catalytic centers of enzymes, as well as for protein-protein and protein-DNA interactions. In plants, Lys acetylation was, until recently, mainly thought to occur on histone proteins as regulatory mechanism for transcription and chromatin functions.However, several central metabolic enzymes of diverse subcellular compartments were recently discovered to be Lys acetylated in Arabidopsis (Arabidopsis thaliana), and in vitro deacetylation tests confirmed that Lys acetylation affects enzyme activities and protein functions.
- Generally, protein acetyltransferases and deacetylases are known to catalyze the reversible modification of the εN-group of Lys. In addition to the classical family of histone deacetylases, a second family of protein deacetylases exists, namely the sirtuins, which are conserved across bacteria, yeast (Saccharomyces cerevisiae), plants, and animals. Sirtuins catalyze an NAD+-dependent deacetylation of acetyl-Lys in proteins and thereby produce a deacetylated Lys, as well as the metabolites nicotinamide and 2′-O-acetyl-ADP-ribose. Sirtuins have recently emerged as key regulators of life span, cell survival, apoptosis, and metabolism in different heterotrophic organisms.
Labs working on this gene
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University,Wuhan 430070, China (L.H., Q.S., F.Q., C.L., Y.Z.)
- Department of Quartermaster,Military Economy Academy, Wuhan 430035, China (L.H.)
- Institut de Biotechnologie des Plantes, Universite´ Paris Sud 11, 91405 Orsay, France (D.-X.Z.)
- Department I of Biology, Ludwig Maximilians University Munich, Grosshaderner Strasse 2, 82152 Martinsried, Germany.
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of
- Institute of Plant Biology, National Taiwan University, Taipei
- University of Chinese Academy of Sciences, Beijing 100049, China
- Institut de biotechnologie des Plantes, Université Paris sud 11, 91405 Orsay, France
Silent information regulator protein Sir2 family protein
NM_001058879.1 GI:115457487 GeneID:4335343
Oryza sativa Japonica Group Os04g0271200, complete gene.
Oryza sativa Japonica Group
ORGANISM Oryza sativa Japonica Group Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliophyta; Liliopsida; Poales; Poaceae; BEP clade; Ehrhartoideae; Oryzeae; Oryza.
|Sequence Coding Region||
<gbrowseImage1> name=NC_008397:11382902..11385613 source=RiceChromosome04 preset=GeneLocation </gbrowseImage1>
<gbrowseImage2> name=NC_008397:11382902..11385613 source=RiceChromosome04 preset=GeneLocation </gbrowseImage2>
<aaseq>MAGVGSAVRRLYLSVYNWAVFFGWAQVLYYAVTTLLESGHEAVY AAVERPLQFAQTAAFLEILHGLVGLVRSPVSATLPQIGSRLFLTWGILWSFPETHSHI LVTSLVISWSITEIIRYSFFGMKEAFGFAPSWLLWLRYSTFMVLYPTGISSEVGLIYI ALPYMKASEKYCLRMPNKWNFSFDFFYASILSLAIYVPGSPHMFTYMLAQRKKALAKA KAA</aaseq>
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- Liu, X., et al., Transcriptional repression by histone deacetylases in plants. Mol Plant, 2014. 7(5): p. 764-72.
- Konig, A.C., et al., The Arabidopsis Class II Sirtuin Is a Lysine Deacetylase and Interacts with Mitochondrial Energy Metabolism. Plant Physiology, 2014. 164(3): p. 1401-1414.
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