In the name of ALLAH the mostBeneficent and most MercifulTitle: Iron Transport in plant cellSubject:- Biochemistry Submitted to:- Dr. Iqbal Hussain Submitted by:- Mubeen Bibi (9517) M.S.C Botany (1st semester) Morning Iron transport in plant cell: Iron uptake: Althoughvery abundant in soils, Fe is poorly soluble in soil. Iron present under Fe hydroxide forms.
In alkaline soils,the accessibility of ferric Fe is strongly decrease. plants need about 108 M F,the solubility of Fe3+Alter from 10_17 M at pH 7 to 10_6 M at pH 3.3. To managewith the low availability of Fe in soils, graminaceous and nongraminaceousplants have two distinct strategie.
StrategyI: Monocotsand all dicots, include Arabidopsis thaliana start the strategy I or reduction-basedstrategy of Fe uptake upon Fe lack. Iron uptake only 3 step 1. acidification ofroot2. activation of ferric iron3.
induction ferrous Fe transport system In many speciesincluding tomato, cucumber of fe deficiency. This acidification step wasproposed plasma membrane ATP-dependent proton pump. The main part in cucumber participatein the loss of iron. The solubility of the Fe III chelate by the reduction of ferric Fe to ferrous Fe performedby a enzyme reductase of ferric. At high concentrationof iron supply destroymature stage of exogenous plant. Among the eight members identified inArabidopsis.
FR06 also present at theplasma membrane but.the main expression in shoots. The major deficiency take place inroot. Nevertheless, irt1 knockout mutant phenotypes are rescued by generous Fe fertilization.This is show , in addition to high-affinity uptake pathway byAtIRT1.
, Fe mayenter plant cells through many ways . low-affinityuptake pathways, which remain to beidentified. StrategyII: Thestrategy formation in responsible to Fe deficiency.
The main part in cucumber in take part Fe deficiency, loss of iron wouldbe responsible the gene CsHA1.Thesolubility of the Fe III chelates is followed by the enzyme use to reduction of ferric Fe to ferrous Fe carry outby a ferric-chelate reductase . Thecharacter of the EMS mutants, frd1-1 and frd1-3, is also fail to start ferric chelate reductase activity.the combinedwith genes homologous to yeast Fe ferric-reductase .
a human NADPH oxidase due to identification of the AtFRO2 gene. . AtFRO2(Ferric oxidase– reductase) present in a plasma membrane ferric-chelatereductase is a enzyme-containing FAD- and NADPH-binding sites.root show theprimaly expression. Atiron supply at high level cause not survive mutant gene and destroy the maturestage of exogenous plant.
Among the eight members identified in Arabidopsis.FRO6 also present at the plasma membrane.Shoot show the first expression atFOR6 no countribute in the reduction of iron.
Innext step, the reduction of ferric chelates to ferrous Fe is take place by Fe2+uptake. Fe2+ high-affinity act astransporter.it is used was identifationby screening an Arabidopsis cDNA. yeast mutant deficient in Fe uptake.
thedisease of strong chlorotic phenotypeand do not survive after the stage of 4–6leaves. During Fe deficiency encoding enzyme increased the gene expression.the is graminaceous species,is produce by specific MA but all plants are able to produce NA. NA which important tu transport andsequestration of metal in plant. The mechanismof PS release in the soil is notknown. However, many pathway involve transport ,anion channel,exocytose havedescribed it. PS are released in the rhizophere and bind toFe+3 .
iron comlex is reported into through transporter . the yellow strip wasidentify by MA due to first Fe(111) Due iron deficiency symptom of chlorosistake place in plant cell. The ZmYS1 gene encodes a plasmamembrane transporter, whose expression in roots and shoots increases during Festarvation.transport is electrogenic Fe-NA .thepH-dependent on that ZmYS1 is a proton–Fe–MA cotransporter . In the ricegenome, 18 yellow-stripe 1 like genes. The protein is localized at the plasmamembrane.
it display in early growth of plant arrest loss of iron resupply. electrogenic transport as shown for ZmYS1.ironis alsoi present in root of rice ;maize etc. The clear difference show betweengrass and non grass plant due to uptake of iron. Recent all data show that, inrice both mechanisms coexist.
Fe(III) PScomplex produce in rice plant.BUT other grass produce in loweramount as compared to rice and can also take up ferrous Fe. The copies of non functional ferric ispresent in rice genome. Rice has likely getting accustomed to submerged growth conditions,which is favorurble in the presence ofFe2+ over Fe3+.it is also decrease theneed for a ferric reductase activity.the expression of a functional recombinantferric chelate reductase in rice improves tolerance to Fe deficiency .
Intracellular Fe distribution: Extremly low concentration of iron present in free cy.However, thetotal Fe concentra on in cells grownin complete medium reaches the micromolar.. Vacuole: IN plant vacuole is also act as iron storage complex. Inparticular, Arabidopsis embryocontainsFe in endodermal vacuole. During germination providing autonomy to the seedlingfor a few days. Ironis also loaded into the vacuole. Yeast cell act as iron/ manganese transporter expressed in shoots and roots of adult plants.
But important function to formation ofseed. Metal mapping with X-raymicrotomography. Fe staining with PERLDAB of vit1 mutant embryos show that Fe does not locate in the vacuoles of theendodermal cells.In theProculature of the cotyledons andembryonic axist as the wild type. But isconcentrated in the vacuoles ofsubepidermal cells of cotyledon seed. chlorotic phenotype during germinationon alkaline soil implying that the adequatelocation of Fe is required for properplant development in these conditions . The FPN2 is transporter in a homologue plant.
mammalianIREG1, is involved in the transportof nickel and cobalt cell . A role of iron cortical root cells hasalso been epidermal celi, buffering the influx of metal into the cytoplasm byvacuolar cell.iron transcripts detection-sufficient root cell,and increased the accumulation under Fe –deficient condition.
Mutant cell reduced the loss of iron due to that failure to sequester Fe into vacuoles leads to alterations in theperception ofFe deficiency . During germination seed,exce mediatexess the retrieval of Fe from the vacuole . Fecontent in nramp3nramp4 seeds isnot altered, the seedlings display a strongchlorotic phenotype when germinatedon low iron. Electron microscopy coupled theelectron spectroscopic imaging as well as Perl/DAB staining showed that doublemutant. Fe remains trapped inside the vacuoles ofendodermal cells and is not assembleduring germination. The analysis of double mutant takepart to the identification of the vacuole as an important Fe storagecompartmentin seeds. In seedlings, transcripts are detected invascular tissues.
proteins are regulated at the transcriptional level by Fe deficiency . Theirinvolvement in Fe mobilization in the germinating seeds is importantfunction in Fe transport in the adultplant . Chloroplast: Heme synthesis and Fe–S clusterarrange in the chloroplast and about90% of the leaf Fe is located in thisorganell.
In the stroma, Fe is coop up by ferritins under a harmless condition. The mechanisms of Fe influx into chloroplastsare not yet explain but uptakeexperiments on separates vesicles frompea chloroplastic inner membrane suggestthe involvement of a Fe2+ uniporter.In agreement with a mechanism involvingFe2+ import into the chloroplast, theferric-chelate reductase .
Seedlings lacking not survive underFe-limiting conditions. The photosynthetic activity in the presence ofFro7 . the Fe concentration is reduced by one third in fro7 chloroplasts. It also show homology withcyanobacterial penetrate and is located in the inner membrane of Arabidoposischloroplasts. The phenotype of PIC1 loss of functionmutants clear show an involvementof the PIC1 protein in photosynthesis.chloroplasts morphogenesis and metalhomeostasis .
Expression of the growth defect offet3fet4 on low Femedia. These results indicates that PIC1 may be involved in Fe uptake intochloroplasts. Mitochondria: Mitochondria are one of the main ogranelles tolocation of Fe–S clusterbiogenesis.
mitochondrial enzymes from the electron transport chain use Fe as a cofactor.The mechanisms of Fe transport intomitochondria are stillunknown.So far, only transport of iron at molecular level involved at Fe homeostasis ofplant mitochondria. ATMproteins are half-molecule ABC transporters.
The yeast homologue is participate the transport of Fe–S clustersout of mitochondria.Atm1D mutant displays a petite phenotype, deflect arespiration .plasma membrane involve Fe uptake systems . null mutant, is a dwarf and chlorotic plantand shows Fe overdose inmitochondriasimilar to the phenotype. mRNA aredetected in all plant tissues. inconstitutive transport of Fe–S clustersfrom mitochondria.
Two close homologues Of ATM3, are also targeted to mitochondria. However,their involvement in Fe homeostasis is not clear yet A recent announceindicates that ATM3 functions in the transport of protein precursor from mitochondriaand that its role in Fe homeostasis in mitochondria is likely indirect. References: 1. Abdel-Ghany SE,Muller-Moule P, Niyogi KK, Pilon M, Shikanai T (2005) Two P-type ATPases arerequired for copper delivery in Arabidopsis thaliana chloroplasts. Plant Cell17:1233–12512.
Arnaud N, Murgia I, Boucherez J, Briat JF,Cellier F, Gaymard F (2006) An iron-induced nitric oxide burst precedesubiquitin-dependent protein degradation for Arabidopsis AtFer1 ferritin geneexpression. J Biol Chem 281:23579–235883. Arnaud N, Ravet K, BorlottiA, Touraine B, Boucherez J, Fizames C, Briat JF, Cellier F, Gaymard F (2007)The iron-responsive element (IRE)/iron-regulatory protein 1 (IRP1)-cytosolicaconitase iron-regulatory switch does not operate in plants. Biochem J405:523–5314 . Askwith C,Eide D, Vanho A, Bernard PS, Li LT, Daviskaplan S, Sipe DM, Kaplan J (1994) The Fet3 gene of S-cerevisiae encodes amulticopper oxidase required for ferrous iron uptake.