環境応答生理学 2015 Physiology of Environmental Responses (484208) Class 6 (29-June, 2016) 江崎文一、且原真木(柴坂三根夫) Ezaki, Katsuhara (Shibasaka) 植物アクアポリンの多様な発現調節と活性調節 Various expressional and activity regulation in plant aquaporins Tissue, organ, and developmental specificity phosphorylation = activation = opening Aquaporin activity depends: protein amount (expression) gating (phosphorylation, pH, Ca,….) heteromerlization intracellular trafficking Gene-family of plant aquaporins and sub-classes. Rice aquaporin genes Plant Cell Physiology 46:568, 2005 (modified) Localization No. of genes Rice Barley PIP Plasma membrane Intrinsic Protein Plasma membrane (PM) 11 19 TIP Tonoplast Intrinsic Protein Tonoplast (Vacuolar membrane) 10 10 NIP Nodulin 26-like Intrinsic Protein Bacteroid membrane, ER, PM 10 8 SIP Small basic Intrinsic Protein ER membrane 2 1 局在 (Localization) 生理的意味を知るのに重要 Important to know physiological role 方法 How 部位別の遺伝子発現解析 mRNA (RT-PCR, micro-array, in site hybridization) 部位別のタンパク質発現解析 Protein (immuno-chemistry/-fluorescence) Organ- and developmental-dependent expression analysis Data from RiceXPro Microarray OsPIP2;1 aquaporin Generally expressed Microarray Target cDNA probed with fluorescence (in total cDNA in samples) Array slide Detection with fluorescence Partial sequence complement to each gene Hundreds gene × samples (samples = several tissues × developmental stages) OsTIP3;1 aquaporin Seed specific Relative mRNA expression level HvTIP3;1 expresses specifically during seed maturation (Barley) オオムギHvTIP3;1の研究データ RNA isolation from deferent stages → quantitative RT-PCR 1800 Root Young Leaf Old LeafLeaf DAP0 0 day after pollination DAP30 30 day after pollination (seed maturing) 1600 1400 1200 1000 800 600 400 200 0 HvTIP1;2 HvTIP2;1 HvTIP2;3 HvTIP3;1 HvTIP4;1 TIP3;1 can be involved in seed desiccation during maturation. Germination (root emergency) TIP1;1 and others (old name g-TIP) (root elongation) TIP2;1(old name d-TIP) PIP2;1 and other PIPs TIP …Vacuole enlargement, cell elongation How different TIPs? Different expression regulation (maybe) タンパク質の局在を調べる (protein) How to detect the tissue distribution of protein? Indirect immunofluorescense (間接蛍光抗体法) Alexa 647 (red) conjugated anti-rat IgG goat antibody Anti-HvPIP1s rat antibody (IgG) (common among HvPIP1s) HvPIP1s Alexa 488 (green) conjugated anti-rabbit IgG goat antibody Anti-HvPIP2;1 (or 2;2) rabbit antibody (IgG) (specific to each molecular species) HvPIP2s 前回既出(Previous class) Barley root(オオムギ根) 内皮 Endodermis 表皮 Epidermis 皮層 Cortex H2O 中心柱 Stele <Apoplastic or Symplastic > 根毛 Root hair PIP1 and PIP2 Co-expression PIP1s HvPIP2;2 Activity regulation via interaction? Homo 2型ホモテトラマー Hetero (InjectionしたRNA量) 1型と2型のヘテロテトラマー PIPs in stomata (孔辺細胞のPIP) H2O H2O 気孔(stomata) 孔辺細胞 (guard cell) AtPIP2;2, 2;3, 2;5, 2;8 Which aquaporins function in guard cells and stomatal movement? 環境応答性 (Response to the environments) 2つの研究例 (2 examples) その1 (No.1) Light 光環境と根のPIPアクアポリン Stomatal opening Rice PIPs in roots Humid (RH=90%) OsPIP2;1 10 OsPIP2;5 8 6 4 2 0 -11 8 0 2 4 6 (x 106 copies / 1μg total RNA) 12 mRNA amounts (x 106 copies / 1μg total RNA) mRNA amounts Dry (RH=40~50%) 12 Transpiration ↑ OsPIP2;1 10 OsPIP2;5 Need much water-uptake 8 6 PIP expression in roots ↑ 4 2 0 -11 8 0 2 4 6 light , but evaporation-dependence 実は蒸散要求(湿度)に応答 (hormonal regulation ?) 環境応答性 (Response to the environments) 2つの研究例 (2 examples) 冠水適応に関与する浮イネのOsTIPs (OsTIPs in Deepwater rice) Water celle Relative protein amount 2.0 OsTIP1:1 1.5 1.0 0.5 0 2.0 OsTIP2;2 1.5 1.0 0.5 0 N H A N H A vacuole 1 day node internode node 3 days Submergence N:non 無冠水 H:Half 半冠水 A:all 全冠水 Submergence (冠水) TIP expression ↑ Vacuolar elongation Cell elongation Internode elongation (節間伸長) ほかのTIP(液胞型)は・・・・ ナシ果実の肥大 (pear fruit ripping) 初期 early stage Cell division 中期~後期 mid to late stages Cell elongation with water absorption TIP aquaporin・・・expression ↑ PIP aquaporin・・・constant expression activation with phosphorylation intracellular trafficking Trafficking of Plant Plasma Membrane Aquaporins: Multiple Regulation Levels and Complex Sorting Signals Chevalier and Chaumont (2015) PCP 56 819 Standard sol. Early Effects of Salinity on GFP-LTP Water Transport in Arabidopsis Roots. Molecular and Cellular Features of Aquaporin PIP1;1-GFP Expression. Boursiac et al. Plant Physiology (2005) 139:790 PIP2;1-GFP Stimulus-induced downregulation of root water transport involves reactive oxygen species-activated cell signalling and plasma membrane intrinsic protein internalization. Boursiac et al. The Plant Journal (2008) 56, 207–218 100 mM NaCl 45 min 120 min 原形質膜マーカータンパク Marker protein for PM Internal compartment Dephosphorylation and internalization (cellular trafficking) function to reduce root water conductance (Lpr) during the initial phase of osmotic stress Salt/osmotic stress Aquaporin P Inactive Aquaporin P Active Aquaporin P 塩ストレス下での根の水透過性制御 (100 mM or 200 mM NaCl 1時間 ) Lpr reduction (透過性下方制御) Less dehydration (脱水抑制) Tolerance (耐性) 根 の 水 透 過 性 LPr [10-6 m s-1 MPa-1] Inactive 1 K305 耐塩性強 (salt tolerance) 0.5 0 0 100 200 NaCl [mM] I743 耐塩性弱 (salt sensitive) Substrates (輸送基質): water Glycerol B(OH)3 Si(OH)4 As(OH)3 NH3 Lactate CO2 H2O2 Low molecular weight, neutral 過酸化水素 H2O2 ケイ素 Si Oocyte実験系 DSkn7 yeast assay Aquaporins transporting H2O2 H2O2 ● ○ Lsi1(=OsNIP2;1)-injected water-injected ROS removal system Lethal Ma et al. (2006) Si analog 68Ge (RI) was used for uptake experiments Skn7 Toxic Assay 0 mM H2O2 0.25 mM H2O2 HvPIP2;4 HvPIP2;3 HvPIP2;5 HvPIP2;2 HvTIP2;2 HvPIP2;1 0.5 mM H2O2 0.75 mM H2O2 pYES2 (Vector) HvPIP2;5 and HvTIP2;2 Are H2O2-transporting Aquaporins 光合成の3つの律速段階とCO2透過性アクアポリンの関係 (photosynthesis and CO2-permeablr aquaporins) 大気 Air CO 固定の律速段階 2 気孔の透過 Stomatal conductance Stomata 気孔 CO2 細胞間隙 Intercellular space 炭酸固定酵素の効率 Cell wall 葉肉細胞 mesophyll cells 原形質膜 Plasmamembrane 細胞質 アクアポリン Mesophyll condctance: 葉緑体 CO2 permeability via AQP Chloroplast RuBisCO activity 細胞壁 CO2 transport activity using oocyte External CO2/H2CO3濃度 PIP cRNA Oocyte(卵母細胞) CA Micropipette Carbonic-anhydrase (CA) CA Micro pH electrode (pH電極) Aquaporin Voltage electrode CO2 CA - CO2 → HCO3 + H+ (pH変化検出) (PCP 55: 251, 2014) 塩ストレス環境とイオン輸送系 その1(理論的側面と分子機構) Salt stress and ion transport #1 (theory and molecular aspect) 塩ストレス環境 Salt stress environment • Arid and semi-arid area <dry land> (high evaporation) • Coastal area (sea water) • Underground salt 細胞の構造と無機イオン輸送の関係 (Inorganic) Ion transport and cell structure Nuc Vacuole Exclude Isolation Ion Selection ATP Ion(low concentration) Accumulation Tolerant/sensitive determinants and transport system • Tolerant?Sensitive? Elements (toxic materials) 標的 Target Detoxification Compartmentation Cell/Individuals Tolerant mechanisms: compartmentation, no absorption, exclusion, to be insensitive •Sensitive(感受性): Originally no tolerant mechanism Inactivation of tolerant mechanism → Disturbance in metabolism and others (Injory mechanism) 輸送の基本 ・・・ 濃度勾配(濃度差) Movement ・・・ Gradient (Concentration) 「電気化学ポテンシャル」(electrochemical potential)とは 「濃度差と電位差の両方を考慮したもの」 (including both gradient of concentration and electric field) + + + + + + - - -(minus charge) --- + + + + + + + + + 10倍の濃度差と、59mVの電位差がつりあう Balance between 10-hold concentration gradient and 59 mV 電気化学ポテンシャル(の正式) Electrochemical potential (formula) 標準状態の化学ポテンシャル (standard chemical potential) μ* 気体定数 (Gas Constant) R 絶対温度 (Abs. Temp.) T 活量 (activity) a 粒子のイオン価 (charge No.) z ファラデー定数 (Faraday Const.) F 電位 (electric potential) φ 平衡電位 (Reversal (Equivalent) potential) Em or Erev ネルンストの式: Nernst equation 膜内外で一価(下図の場合K+)が平衡しているときは・・・ [ K ]in RT [ M ]in 59 log (mV ) Em ln zF [ M ]out [ K ]out 外側基準 (outer is zero standard) K+ K + K+ K + K+ K+ K+ K+ K+ K+ K+ (In case of K+) ポンプ (Pump) エネルギーを直接使って、電気化学ポテンシャ ル勾配に逆らって、物質を輸送する (Against electrochemical gradient, using energy) H+ H+ H+ H+ H+ ATP ADP + Pi H+ Example: H+ -ATPase 輸送速度は毎秒102個 (102 molecules per sec) トランスポーター (Transporter) ある物質X(たいていH+)の電気化学ポテン シャル勾配を利用して、目的の物質Yを濃度勾 配に逆らって輸送する (Using electrochemical gradient of X (H+in most case), transporting Y against Y’s electrochemical gradient) Na+ H+ H+ Na+ Na+ H+ + H + Na H+ H+ Na+ Na+ Na+H+ Example: Na+-H+ -antiporter 輸送速度は毎秒103個 (103 molecules per sec) チャネル (channel) 一部のトランスポーター (Some Transporter) 目的の物質を、電気化学ポテンシャル勾配 濃度勾配にしたがって(促進的に)輸送する (Transport X according to its electrochemical gradient) + K+ K+ - - - - K K+ K+ glucose glucose - - - - K+ Example: K+ -channel 輸送速度は毎秒108個以上 (108 molecules per sec) glucose Example: Glucose transporter 輸送速度は毎秒103個 (103 molecules per sec) 細胞膜電位 (静止電位) Membrane potential (Resting potential) ⋍ K+の平衡電位 (動物も植物も) Em of K+ 細胞膜電位 = 非起電性成分 Membrane potential non-electrogenic ones (細胞内の非移動性負電荷) 動物と植物は ここが違う! Plant unique intracellular immobile negative charges + 起電性成分(起電性ポンプ) electrogenic ones (electrogenic pump) Resting potential of living cells Animal cells Plant cells Na+-K+-ATPase (electrogenic pumps) H+-ATPase 2K + H+ 3Na + out in ATP ADP+Pi -70 ~ -90 mV ATP ADP+Pi -100 ~ -200 mV Exclusion of Na+(How to low [Na+]cyt) Animal High[Na+]outが基本 Plant [Na+]out -freeが基本 Na+-K+-ATPase 2K+ 3Na+ H+ out in No Na+-K+-ATPase except sea algae (海産藻類は例外) ATP Na+ ADP+Pi For exclusion of [Na+]cyt ・・・ Na+/H+ antiporter 二次輸送システムの基本的な違い X Animal Plant Using Na+ gradient Using H+ gradient Na+ symport antiport (co-trasnport) Y X H+ Y Ion channel study using the electrophysiology Ion flux was detected as electric current (cell recording) 従来の電気生理 (classical electrophysiology) Electric current is sum of single-channel currents パッチクランプ (Patch Clamp) 1991年 ノーベル賞 Nobel prize 1991 (Single channel recording) Example of ATP-dependent cation channel open ion+ close Erev (逆転電位) ↑外向き電流 outward current ion+ ↓内向き電流 inward current Outward current ・・・ + ion efflux (外向きの流れ) または - ion influx(内向きの流れ) Erev tells flux ions and selectivility (1) Erev [ K ]in RT [ M ]in 59 log (mV ) ln zF [ M ]out [ K ]out RT Pk[ K ]in PNa[ Na ]in PCl[Cl ]out (2) Erev ln F Pk[ K ]out PNa[ Na ]out PCl[Cl ]in [ K ]in [ Na ]in PNa (3) Erev 59 log , PCl 0 Pk [ K ]out [ Na ]out (1)イオンMの平衡電位(ネルンストの式)と、MがK+の場合 (2)3つの主要イオンで電位が決まる場合のGoldmanの式 (3)Cl-の透過性が低い場合、Na+とK+の選択性αが求められる If Cl- permeabiliy (PCl) is low, selectivity between Na+ and K+ is calculated. Erev (逆転電位) PNa/PK (α)= 0.28 (淡水産車軸藻の場合) Na+はK+のチャネルを 通って細胞に入る 原形質膜 K+ out in [K+]in = 100, [K+]out = 0.1, [Na+]in = 0, [Na+]out = 100 (cyt side is “in”) Na+ Ca2+ ATP 耐塩性の高い車軸藻(汽水産)の場合、αはほとんど 0、すなわちNa+はK+のチャネル通れず、細胞に入ら ない (In blackish characae, α ≒0) カリウムチャネルの分子構造 Molecular structure of K channel 放線菌のKcsAチャネル Actinomycetes Kcs (現代科学2004年1月 号より) By Mackinonn 2003年ノーベル賞 Nobel Prize 2003 カリウム輸送系とナトリウムの吸収 Potassium transporter and sodium uptake Multi-system: Physiology and transporters オオムギ切断根のカリウム吸収速度と培地カリウム濃度の関係 複数の輸送体の寄与を示唆 Epstain, Nature 212:1324 (1966) 塩ストレスでは・・・ Under salt stress・・・ + Na + K 植物(シロイヌイナズナ)のカリウム輸送系遺伝子 Na+↑ K+↓ 代謝と膜電位の 攪乱 Disturbance of membrane potential and metabolism K+ out in Na+ Na-K co-transporter Arabidopsis HKT (Science 270:1660, 1995) Na/K 共輸送 symport 「植物の膜輸送システム」 (秀潤社)より Na-K co-transporter Arabidopsis HKT (Science 270:1660, 1995) Arabidopsis HKT K+ out in Na+ X (normal (WT) transports Na) Na+透過に関与するのは A240とL247 300 mM NaCl in solid medium Toxic assay からの復帰変異の選抜 別のNa輸送システム(SOS系) Salt stress sensitivity test/bending assay inversion 5-day-old plant without salt stress wild type Sensitive Mutant (SOS mutant) by Dr. Zhu salt stress for several days SOS1-mutant K+ Na+ KAT AKT HKT ・・・ SOS3 SOS2 Na+ X NHE Na+ H+ SOS1 (Na/H antiporter) SOS2: CIPK24 SOS3: CBL4 後述 Later Localization and function of AtHKT and SOS1 AtHKT1とSOS1の植物体内での生理的役割 SOS1: Na-H antiporter AtHKT1 : Na-transporter (but most plant HKT is Na/K transporter) High sodium (Na) ; Salt stress K-deficiency and moderate Na; Substitution 代替(有益) Rice (Koshihikari) ○ イネ rice オオムギ barley ワタ cotton キャベツ cabbage ホウレンソウ spinach ビート beat ・・・ × トウモロコシ maize アブラナ Brasicca ダイズ Soybean •(「植物栄養学」第2版) Molecular mechanism for Na uptake in rice: One of OsHKT? イネHKT OsHKT2;1 expression under K-deficiency → candidate? (EMBO J 26:3003, 2007) (Plant Physiology 152:341, 2010) OsHKT2;1 : Na-transport (not K-dependent) OsHKT2;2: K-dependent Na-transport and Na-dependent K-transport (タバコ培養細胞に発現させて測定 in Nicotine cell) NOTE: Difference between rice and Arabidopsis HKTs シロイヌナズナHKTはイネと違う Schematic summaries of Na+ influx pathways into saline roots (in case of rice) Primary protective mechanisms mediated by Na+ transporters on important biological membranes Rice5:11 (2012)) Apoplastic bypath flow 注意:植物種によって、イオン選択性は異なる NOTE: Difference among plat species 塩ストレスに応答するカルシウムシグナル伝達系 Calcium signalling pathway in salt stress responses 左:酵母細胞 (left: yeast) 右:植物細胞 )rightl: plant) (基本形に相同である, identical) Trends in plant science, 3:411-412 (1998)より CAM:カルモジュリンcalmodulin CDPK:カルシウム依存PK PK:タンパク質リン酸化酵素 PP:タンパク質脱リン酸化酵素 CNA/B:カルシュニューリンA/B CalcineurinA/B (CBL:CNB-like)←CAMが結合(Ca依存的) 植物のCBLシグナル系 • CBLs/CIPKs CBL:1~9 (Calucinulin-B like proteins) CIPK1~25 (CBL-interacting protein kinase) 2, 11-17, 19-25 7, 9 Drought-responsive 1, 4, 6, 8,18 3, 5, 10 Black: CIPKs Blue:CBL1 Red:CBL9 Cold-responsive Sheng Luan et al. タンパク質相互作用を調べる Two-hybrid法 The CBL–CIPK network in plant calcium Signaling. Sheng Luan Trends in Plant Science Volume 14, Issue 1, 37-42 (2008) カルシウムの関与する他の系 カルシウム依存性蛋白質リン酸化 伸展活性化カルシウムチャネル Mechanosensitive Ca-channel Aquaporins and water homeostasis in plants Kjellbom et al. TIPS, 1999, 4:308 (CDPK and Aquaporins) どうやって細胞内Caの変動を調べるか? How to know changes of cytoplasmic Ca2+? Fluorescence probes (Fla-2....) (spatial distribution) (Time course) 「植物の生化学・分子生物学」 Aequorin:a monomeric Ca2+-binding protein (Mr, 21,400) that emits light upon reacting with Ca2+. Aequorin and GFP (Nobel prize 2008 Prof. Shimomura) Ca2+→aequorin(Blue)→GFP(Gleen) 複合体での蛍光共鳴エネルギー移動 Energy shift between aequorin and GFP 日経サイエンス 2009年11月号より オオムギ根で発現させた例 (GFP in barely root) 環境ストレスと細胞内シグナル伝達 Intracellular signaling against environmental stresses 受容 → Reception 伝達 Transmission 10 SnRK2 genes (Arabidosis) 転写因子 → Transcriptional factor シス因子 → Cis-elements ABAとDREB: 低温と乾燥に対す るシロイヌナズナ の応答 Cold and osmotic response in Arabidopsis Phenotypes of srk2d/i and srk2d/e/i mutants. Nakashima K et al. Plant Cell Physiol 2009;50:1345-1363 SnRK2D = SnRK2.2 SnRK2E = SnRK2.6 SnRK2I = SnRK2.3 ABA 種子 休眠 (dormant) 三重変異体 (Triple mtant) 種子 休眠解除 (no dormat) ABA response1:種子休眠 seed dormancy ABA responce2:ストレス耐性 stress tolerance Osmotic stress Arabidopsis decuple mutant reveals the importance of SnRK2 kinases in osmotic stress responses in vivo Fujii H et al. PNAS 2011;108:1717-1722 次回7/13課題論文 Next paper (July 13)
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