1. ATP universal energy “currency” 2. Structure of ...biophys.med.unideb.hu/sites/default/files/course_material/2016/04/... · -Similarities with other organelles (chloroplasts,

Mitochondrion. Synthesis of ATP.

1. ATP universal energy “currency”

2. Structure of mitochondrion

3. Chemiosmotic theory

4. Synthesis of ATP

5. Biogenesis of mitochondrion

Lodish et al.: Molecular Cell Biology (4th ed.)

16.1 Oxidation of Glucose and Fatty Acid to CO2

16.2 Electron Transport and Oxidative Phosphorylation

17.1 Synthesis and Targeting of Mitochondrial

and Chloropast proteins

9.7 Organelle DNAs

Alberts et al.: Essential Cell Biology 4th ed.

Chapter 14. pages 447-469, 479-481.

Chapter 15. pages 487-497.

Key words:

ATP; Glycolysis; ATP synthase; anaerobic metabolism;

chemiosmotic theory; mitochondrial matrix; christae;

mitochondria; chloroplasts; oxidative phosphorylation;

electrochemical proton gradient; inner membrane;

outer membrane; intermembrane space; porin; cardiolipin;

mitochondrial DNA; mitochondrial DNA coding;

mitochondrial ribosome; protein import into mitochondria;

respiratory chain; targeting sequence; heat shock protein70;

heat shock protein60; thermogenin;

proofs for bacterial origin of mitochondrium;

1. ATP universal energy “currency”

ATP4- + H2O = ADP3- + P

i(ΔG = - 30.6 kJ/mol)

- glycolytic pathway (1 glucose 2 ATP)

- Photosynthesis (light energy)

- Oxidative phosporylation (presence of oxigen,

chemical energy)

C6H

12O

6+ 6O

2+ 32 Pi2- + 32ADP3- + 32H+ → 6CO

2+ 32ATP4- + 38H

2O

1. ATP universal energy “currency”

1. ATP universal energy “currency”

Anaerobic metabolism

1. ATP universal energy “currency”

2. Structure of mitochondrion

Structure of mitochondrion

-Outer membrane, 50% protein, 50% lipid, role of porin (5 kDa)

-Inner membrane, 76% protein, 24% lipid, role of cardiolipin

-Intermembrane space

-Matrix, citric acid cyle, oxidation of pyruvate, fatty acids

-Cristae, increase in membrane surface

2. Structure of

mitochondrion

2. Structure of mitochondrion

Molecules upto 5000 Da

can go through the outer

membrane of the

mitochondrium

Porin

2. Structure of mitochondrion

Insulation of innermembrane

Hydrogen ion cannot flow through

Cardiolipin has four fatty acid chains!

2. Structure of mitochondrion

2. Structure of mitochondrion

2. Structure of mitochondrion

Movie

3. Chemiosmotic theory

Chemiosmotic theory

-proton motive force (electrochemical potential)

-Generation of proton gradient

-Use of proton gradient

-Experiment demonstration that chemiosmosis is universal

3. Chemiosmotic theory

Concentration gradient

+

Potential difference

=

Electrochemical potential

μH

+1

= μ0

H+1

+ RT ln cH

+1

+ zFΨ1

μH

+2

= μ0

H+2

+ RT ln cH

+2

+ zFΨ2

ΔG = n Δ μ = RT ln(c1/c

2) + 1FΔΨ

Gibbs free = concentration + Potential

energy gradient difference

Electrochemical Potential

3. Chemiosmotic theory

ΔpH ΔΨ

ΔpH ΔGpH

ΔΨ ΔGΨ

ΔGtotal

Mitochondr. 1.0 pH - 5.8 kJ - 160 mV - 15.4 kJ - 21.2 kJ

Chloroplast 3.5 pH - 20.3 kJ 0 0 - 20.3 kJ

Bacterium 2.0 pH - 11.6 kJ - 70 mV - 6.7 kJ - 18.3 kJ

Concentration gradient Potential difference+Total Gibbs

Free Energy=

Energy content of the proton gradient

3. Chemiosmotic theory

3. Chemiosmotic theory

Thylakoid

3. Chemiosmotic theory

Generation of proton gradient

Peter Mitchell, 1978

3. Chemiosmotic theory

Generation of

Proton gradient

3. Chemiosmotic theory

Use of proton gradient

Thermogenin protein

(MW. 33,000) (UCP)

Brown fat tissue

Cold adapted animals

Other use of proton gradient

Heat production (thermogenin)

Cold adapted animals

Infant

Brown fat tissue

3. Chemiosmotic theory

(thermogenin, UCP)

3. Chemiosmotic theory

Use of proton gradient (16x16 proton per revolution)

Flagellum

3. Chemiosmotic theory

Use of proton gradient - transport

3. Chemiosmotic theory

Chemiosmosis is universal

4. Synthesis of ATP

Synthesis of ATP

-Structure of F0-F

1complex

-ATP synthase as a rotor

-Experiment showing rotation of ATP synthase complex

4. Synthesis of ATP

Structure of F0-F

1complex

4. Synthesis of ATP25nm

8 nm

Paul Boyer

John E. Walker

1997

ATP synthase

as a rotor

4. Synthesis of ATP

4. Synthesis of ATP

Experiment showing rotation of ATP synthase complex

4. Synthesis of ATP

Experiment showing rotation of ATP synthase complex

5. Biogenesis of mitochondrion

Biogenesis of mitochondrion

-Mitochondrial DNA, circular DNA, 5-10 copies

-Alteration in the standard genetic code

-Importing of mitochondrial proteins from the cytosol

uptake-targeting sequences

-Similarities with other organelles (chloroplasts, peroxisomes)

-The origin of mitochondrion

5. Biogenesis of mitochondrion

Euglena gracilis

5. Biogenesis of mitochondrion

Euglena gracilis

Nucleus

Mitochondrion

Mitochondrial DNA

5. Biogenesis of mitochondrion

Human mtDNA 16,569 bp

5. Biogenesis of mitochondrion

Alteration in the universal genetic code

5. Biogenesis of mitochondrion

5. Biogenesis of mitochondrion

Importing cytosolic proteins

5. Biogenesis of mitochondrion

5. Biogenesis of mitochondrion

5. Biogenesis of

mitochondrion

Targeting

cytosolic

proteins

5. Biogenesis of mitochondrion

Similarities with

other cell organelles

5. Biogenesis of mitochondrion

Origin of mitochondria

Mitochondrion. Synthesis of ATP.

1. ATP universal energy “currency”

2. Structure of mitochondrion

3. Chemiosmotic theory

4. Synthesis of ATP

5. Biogenesis of mitochondrion

Proofs that the Mitochondrion

has bacterial origin:

1. Circular DNA. (No chromosomes!)

2. Size of mitochondrion (1 micron!)

3. Two membranes. (Outer membrane => host cell,

inner membrane => bacterium

4. Alteration from the STANDARD CODE!

5. Ribosome (60S, bacterial ribosome)

6. Heat shock protein (Hsp60) resemblance to bacterial Hsp.

The relationship between atmospheric O2

levels

and major stages in evolution of living organisms

Evolution of oxidative

phosphorylation mechanism

(One possible sequence)