In Fe III chelate by the reduction of ferric

 

In the name of ALLAH the most
Beneficent and most Merciful

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                          Iron Transport in plant cell

Subject:-                 

                                            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:                

Although
very 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 manage
with the low availability of Fe in soils, graminaceous and nongraminaceous
plants have  two distinct strategie.

 

Strategy
I:

 

Monocots
and all dicots, include Arabidopsis thaliana start the strategy I or reduction-based
strategy of Fe uptake upon Fe lack. Iron uptake only 3 step

 

1. acidification of
root

2.  activation of ferric iron

3.  induction ferrous Fe transport system

 

In many species
including tomato, cucumber of fe deficiency. This acidification step was
proposed plasma membrane ATP-dependent proton pump.

 

 

 

 

 

 

 

 

The main part in cucumber participate
in the loss of iron. The solubility of 
the Fe III chelate by the reduction of ferric Fe to ferrous Fe performed
by a enzyme reductase of ferric. At high concentrationof iron supply destroy
mature stage of exogenous plant. Among the eight members identified in
Arabidopsis.FR06 also  present at the
plasma membrane but.the main expression in shoots.

 

The major deficiency take place in
root. Nevertheless, irt1 knockout mutant phenotypes are rescued by generous Fe fertilization.
This is show , in addition to high-affinity uptake pathway byAtIRT1., Fe may
enter plant cells through many ways . low-affinity

uptake pathways, which remain to be
identified.

 

 

 

Strategy
II:

 

 

The
strategy formation in responsible to Fe deficiency. The main part  in cucumber  in take part Fe deficiency, loss of iron would
be responsible  the gene CsHA1.

The
solubility of the Fe III chelates is followed by the enzyme use to  reduction of ferric Fe to ferrous Fe carry out
by a ferric-chelate reductase .

 

The
character of the EMS mutants, frd1-1 and frd1-3, is also  fail to start  ferric chelate reductase activity.the combined
with   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-chelate
reductase is a enzyme-containing FAD- and NADPH-binding sites.root show the
primaly expression.

 

 

At
iron supply at high level cause not survive mutant gene and destroy the mature
stage 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.

 

 

In
next step, the reduction of ferric chelates to ferrous Fe is take place by Fe2+

uptake
.  Fe2+ high-affinity act as
transporter.it is used  was identifation
by screening an Arabidopsis cDNA. yeast mutant deficient in Fe uptake.the
disease of strong chlorotic phenotypeand do not survive after the stage of 4–6
leaves.

 

 

 

 

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 and
sequestration of metal in plant. The mechanism

of PS release in the soil is not
known. However, many pathway involve transport ,anion channel,exocytose have
described it.

 

 PS are released in the rhizophere and bind to
Fe+3 .iron comlex is reported into through transporter . the yellow strip was
identify by MA due to first Fe(111) Due iron deficiency symptom of chlorosis
take place in plant cell.

 

The ZmYS1 gene encodes a plasma
membrane transporter, whose expression in roots and shoots increases during Fe
starvation.

transport is electrogenic Fe-NA .the
pH-dependent on that ZmYS1 is a proton

–Fe–MA cotransporter . In the rice
genome, 18

yellow-stripe 1 like genes.

 

The protein is localized at the plasma
membrane.it display in early growth of plant arrest loss of iron resupply.  electrogenic transport as shown for ZmYS1.iron
is alsoi present in root of rice ;maize etc.

 

 

The clear difference show between
grass and non grass plant due to uptake of iron. Recent all data show that, in

rice both mechanisms coexist.Fe(III) PS
complex produce in rice plant.

BUT other grass produce in lower
amount as compared to rice and can also take up ferrous Fe.

 

 

The copies of non functional ferric is
present in rice genome. Rice has likely getting accustomed to submerged growth conditions,
which is  favorurble in the presence of
Fe2+ over Fe3+.it is also  decrease the
need for a ferric reductase activity.the expression of a functional recombinant
ferric chelate reductase in rice improves tolerance to Fe deficiency .

 

Intracellular
 Fe distribution:

 

Extremly  low concentration of iron present in free cy.
However, the

total Fe concentra on in cells grown
in complete medium reaches the micromolar..

 

 

 

 

 

 

 

Vacuole:

 

 

IN  plant 
vacuole is also act as iron storage complex.   In
particular,  Arabidopsis embryocontains
Fe in endodermal vacuole. During germination providing autonomy to the seedling
for a few days.  

Iron
is 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 of
seed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Metal mapping with X-ray
microtomography.  Fe staining with PERL
DAB of vit1 mutant embryos show that Fe does not locate in the vacuoles of the
endodermal cells.In the

Proculature of the cotyledons and
embryonic axist as the wild type. But is

concentrated in the vacuoles of
subepidermal cells of cotyledon seed.

 

chlorotic phenotype during germination
on alkaline soil implying that the adequate

location of Fe is required for proper
plant development in these conditions .

 The  FPN2 is transporter in a  homologue plant.  mammalian

IREG1, is involved in the transport
of  nickel and cobalt cell .

 

A role of iron cortical root cells has
also been epidermal celi, buffering the influx of metal into the cytoplasm by
vacuolar  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 the
perception of

Fe deficiency .

 

 

During germination seed,exce mediat
exess the retrieval of Fe from the vacuole . Fecontent in nramp3nramp4 seeds is
not altered, the seedlings display a strongchlorotic phenotype when germinated
on low iron.

 

Electron microscopy coupled the
electron spectroscopic imaging as well as Perl/DAB staining showed that double
mutant. Fe remains trapped inside the vacuoles of

endodermal cells and is not assemble
during germination.

 

 

The analysis of double mutant take
part to the identification of the vacuole as an important Fe storage
compartmentin seeds. In seedlings, transcripts are detected invascular tissues.
proteins are regulated at the transcriptional level by Fe deficiency . Their
involvement in Fe mobilization in the germinating seeds is important

function in Fe transport in the adult
plant .

 

 

Chloroplast:

 

Heme synthesis and Fe–S cluster
arrange  in the chloroplast and about

90% of the leaf Fe is located in this
organell. In the stroma, Fe is coop up by ferritins under a harmless condition.

 

 

The mechanisms of Fe influx into chloroplasts
are not yet explain but uptake

experiments on separates vesicles from
pea chloroplastic inner membrane suggest

the involvement of a Fe2+ uniporter.
In agreement with a mechanism involving

Fe2+ import into the chloroplast, the
ferric-chelate reductase .

 Seedlings lacking not survive under
Fe-limiting conditions. The  photosynthetic activity in the presence of
Fro7 . the Fe concentration is reduced by one third in fro7 chloroplasts.

 

It also show homology with
cyanobacterial penetrate and is located in the inner membrane of Arabidoposis
chloroplasts.

 

 

The phenotype of PIC1 loss of function
mutants clear show an involvement

of the PIC1 protein in photosynthesis.
chloroplasts morphogenesis and metal

homeostasis . Expression  of the growth defect offet3fet4 on low Fe
media. These results indicates that PIC1 may be involved in Fe uptake into
chloroplasts.

 

 

Mitochondria:

 

 Mitochondria are one of the main ogranelles to
location of Fe–S cluster

biogenesis.
mitochondrial enzymes from the electron transport chain use Fe as a cofactor.
The mechanisms of Fe transport  into
mitochondria are still

unknown.
So far, only transport of iron at molecular level involved at Fe homeostasis of
plant mitochondria.

 

ATM
proteins are half-molecule ABC transporters. The yeast homologue  is participate the transport of Fe–S clusters
out of mitochondria.Atm1D mutant displays a petite phenotype, deflect a
respiration .plasma membrane involve Fe uptake systems .

 

 null mutant, is a dwarf and chlorotic plant
and shows Fe overdose in

mitochondria
similar to the phenotype.  mRNA are
detected in all plant tissues.

in
constitutive transport  of Fe–S clusters
from mitochondria.Two close homologues Of ATM3, are also targeted to mitochondria.

 

However,
their involvement in Fe homeostasis is not clear yet A recent announce
indicates that ATM3 functions in the transport of protein precursor from mitochondria
and 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 are
required for copper delivery in Arabidopsis thaliana chloroplasts. Plant Cell
17:1233–1251

2.     
 Arnaud N, Murgia I, Boucherez J, Briat JF,
Cellier F, Gaymard F (2006) An iron-induced nitric oxide burst precedes
ubiquitin-dependent protein degradation for Arabidopsis AtFer1 ferritin gene
expression. J Biol Chem 281:23579–23588

3.     
Arnaud N, Ravet K, Borlotti
A, Touraine B, Boucherez J, Fizames C, Briat JF, Cellier F, Gaymard F (2007)
The iron-responsive element (IRE)/iron-regulatory protein 1 (IRP1)-cytosolic
aconitase iron-regulatory switch does not operate in plants. Biochem J
405:523–531

4 .  Askwith C,
Eide D, Vanho A, Bernard PS, Li LT, Daviskaplan S, Sipe DM, Kaplan J  (1994) The Fet3 gene of S-cerevisiae encodes a
multicopper oxidase required for ferrous iron uptake. Cell 76:403–410