Download Mitochondrium

outer membrane
inner membrane
crista
matrix
Mitochondrium – Peroxisome - Chloroplast
Dr. habil. Kőhidai László
Assoc. Prof.
Dept. Genetics, Cell & Immunobology
Semmelweis University
2008
History
 Altmann – describes Mch
 Benda - name „Mitochondrium” was
given by him
 Warburg - invetigated the enzymes
of respiratory chain
 Lehninger – described oxydative
phosphorylation
Morphology
Network of Mch in a fibroblast cell
Detection of ATP-syntase
Characteristic data
•
Size:
7 x 0.5 mm
BUT: wide range in different cell types !
•
Number: depends on the energy
requirements/budget of the cell
sperim - 24
WBC. 300
liver cell - 500-2500
Chaos-Chaos - 500.000 !
ameba
Composition
compartmentalisation
Outer membrane
• poor in proteins
• characteristic protein: porin
• (b-sheet– trimers
form channels)
• permeability up to 5000 dalton
Inner membrane
• 70% proteins
• e- - transporter chaini
• ATP synthesis
• other point impermeable – 20% cardiolipin
Matrix
• Pyruvate dehydrogenase complex
• Enzymes of citric acid cycle
• Enzymes of b-oxydation of fatty acids
• Enzymes of amino acid oxydation
• DNA, ribosomes
• ATP, ADP, Pi
• Mg2+, Ca2+, K+
Inner membrane of Mch
crista
tubular
fingerprint-like
berry-like
Localization in the cell
Basal striation
Mch as osmotic regulator of the cell
normal
condensed
Significant H20 ration of matrix moves to
the intermembraneous space and forms a
„condensed” comformation
Relation of biochemical processes in Mch.
pyruvate
fatty acid
Acethyl-CoA
CO2
ATP
Citric acid cycle
H2O
O2
NADH+H
FADH2
Terms of Chemiosmotic theory
•
•
•
•
•
Mch. Respiratory chain – moves electrons
- pumps H+ into
intermembrane space
Mch. ATP synthase works also as a H+ pump.
H+ in
Reversible mechanism:
H+ out
ATP synthesis
ATP cleavage
Several carrier molecules for metabolites, ions – in the
inner membrane of Mch.
Other point of the inner membrane of Mch. is
impermeable for H+ and OH-.
H+
Intermembrane
space
H+
H+
UQ
I.
II.
III.
IV.
Matrix
I.
II.
III.
IV.
NADH dehydrogenase
Succinyl dehydrogenase
Ubiquinone – cytochrom c oxydoreductase
Cytochrom oxydase
Enzyme systems of
inner membrane in Mch
I.
Acidic pH
Redox potential
INCREASING:
I. < III. < IV.
II.
H+
e-
III.
IV.
Resting phase
Matrix [H+]=10-9 M
[K+] = [Cl-] = 0.1 M
[H+]=10-9 M
Intermembrane space
[H+]=10-9
Matrix
[K+]<[Cl-]
M
ATP
H+
K+
Intermembrane K+
space
[H+]=10-7 M
Ionophore treated
(Valinomycin)
Electrochemical proton-gradient
pH gradient
DpH
membrane-potential
DV
ATP synthesis
NADH
NAD+
NADH dehydrogenase
H+
Q
b-c1
complex
cyt c
Electron transport
in Mch
cytochrome oxydase
O2
H2O
Knob-like protusions of the inner
Mch membrane
ATP-synthase
proton carrier
head
basis
Structure of ATP-synthase
F1 ATP-ase
(6 subunits)
Transmembrane H+ carriers (9 subunits)
ATP-synthase
e - rotor
a, b, d - stator
Experimental evidence
Bacterio-rhodopsin
ATP synthase
H+
ADP + Pi
H+
ATP
H+ H+
+
H
H+
H+
ATP
ADP + Pi
H+
ADP + Pi
ATP
Transports required by
ATP-synthase
Symport
Antiport
H+
ATP
H2PO4
-
ADP
ATP
ADP
H+
Adenine nucleotie translocase
H+
H2PO4- H+
Phosphate translocase
Brown adipose tissue
Mch.
H+
I.
H+
II.
III.
H+
Heat
H+
IV.
thermogenin
Transports
Signal seq.
! Hsp70 !
Receptor
Contact-point
Translocon
GIP
Mch. Hsp-k
Origin of Mitochondrion
• De novo synthesis
• Division
• Endosymbiont theory
Archaic Cyanobacteria – 1.5 x 109 yrs ago
 porin (Gram (-) bact.)
 electron transport chain
 ATP synthase
 mt DNS
 ribosome
BUT: Giardia has NO Mch (anaerob)
Origin of Mitochondrion 2
•
•
•
Composition of outer membrane – eukaryotic
type; the inner membrane is composed by
prokaryotic components
Mch has own protein synthetic system, the
starter amino acid is formyl-Met
Inhibitors of protein synthesis in Mch:
antibiotics acting on bacterial protein
synthesis
Network of Mch in budding
S. cerevisiae
CELL PROLIFERATION
Isotope
labelling
mt-DNA
• ring shape, 5 –10 copies/Mch.
• 20 Mch genes are coding proteins
• there are no introns
• few regulator genes
• no histons
• repliation, transcription, translation
• 22 tRNA, 2 rRNA
Human mt-DNA
rRNA
Cyt b
ND1; 2
ND3-6
I.
III.
II.
ATP-syntase
Mch myopathy
Single
fibre
Crystalline
structure
in the matrix
of Mch
Clusters
of fibers
Mass of
pathologic
Mch-s
Peroxisome
• Single membrane coverage
• Selective import of proteins
• No genome
• Oxydative enzymes:
catalase
urate oxydase (crystalloid)
Origin of peroxisome
• O2 producing bacteria – early phase of phylogeny
• the O2 is toxic to other cells/organisms
• peroxisome could neutralize the O2 and its radicals
in the cytoplasm
Functions of peroxisome
• RH2 + O2
• H2O2 + R’H2
R + H2O2 (toxic)
R’ + 2H2O
catalase (liver, kidney)
 b-oxydation: alkyl chain - (C2 ac.CoA)n
Peroxisomes in plants
• In plants
leafs:
photorespiration - O2
consumption; CO2
germination: glyoxylate cycle
(glyoxysome)
Fatty acid
ac. CoA
succinate
glucose
Peroxisome in plants
peroxisome
glyoxisome
lipid
Peroxisome
•
import of proteins
- 3 amino acid signal sequence on C-terminal
- PAF-1 – peroxisomal assembly factor-1
PAF-1
• Zellweger syndrome
protein to be impoted is affected - empty peroxisomes
(brain, liver, kidney affected; lethal)
Gene transfection Zellweger syndrome
PXR1
Chloroplast
Thylakoid
membrane
(light reaction)
Stroma
(dark reaction)
Engelmann-experiment
(1894)
Oxygen-requiring bacteria move to
regions where oxygen is being
liberated by photosynthesis
Photopigments of chloroplast
Z-scheme of
electron transport
in chloroplast
Chloroplast – NAPH / ATP synthesis
Comparison of ATP generation
in Mch - Chloroplast