Your SlideShare is downloading. ×
0
 
Lectures by John F. Allen School of Biological and Chemical Sciences, Queen Mary, University of London Cell Biology and De...
Cell Biology and Developmental Genetics Lectures by John F.  Allen Endosymbiosis and the origin of bioenergetic organelles...
Cell Biology and Developmental Genetics Lectures by John F. Allen Slides and supplementary information:  jfallen.org/lectu...
School of Biological and Chemical Sciences Seminars WEDNESDAYS AT 12 NOON IN G23, G. E. FOGG BUILDING 3 February 2010 Dr N...
Lecture 4   Why do chloroplasts and mitochondria have genomes?
I II III IV ATPase Mitochondrial matrix Inter-membrane space
Chloroplast stroma Thylakoid lumen Cyt  b 6 - f Photosystem I ATPase Photosystem II RubisCO
Problem Why Do Mitochondria and Chloroplasts Have Their Own Genetic Systems? Why do mitochondria and chloroplasts require ...
Proposed solutions (hypotheses) There is no reason. “That’s just how it is”. (Anon) The “Lock-in” hypothesis. (Bogorad, 19...
Proposed solution (hypothesis) Why Mitochondria and Chloroplasts Have Their Own Genetic Systems Allen, J. F. (1993) J. The...
Bacterium Endosymbiont Bioenergetic organelle
1. As now generally agreed, bioenergetic organelles evolved from free-living bacteria.  2. Gene transfer between the symbi...
Co -location   for  R edox   R egulation   -   CoRR  Prediction: Explanation of previous knowledge Distribution of genes f...
Co -location   for  R edox   R egulation   -   CoRR  Prediction Explanation of previous knowledge Distribution of genes fo...
Redox regulation
Redox regulation Nucleus Cytosol N-phase Mitochondrial matrix O 2 H 2 O
I II III IV ATPase Mitochondrial matrix Inter-membrane space
I II III IV ATPase Mitochondrial matrix Inter-membrane space H + H + NADH O 2 ATP ADP H 2 O NAD + succinate fumarate H + H +
Redox regulation Nucleus Cytosol N-phase Mitochondrial matrix O 2 H 2 O Allen JF (2003) The function of genomes in bioener...
Co -location   for  R edox   R egulation   -   CORR  Prediction Explanation of previous knowledge Distribution of genes fo...
Redox regulation
Redox regulation Light Light Nucleus Cytosol N-phase Chloroplast stroma CO 2 CH 2 O
Chloroplast stroma Thylakoid lumen Cyt  b 6 - f Photosystem I ATPase Photosystem II RubisCO
Cyt  b 6 - f Photosystem I ATPase Chloroplast stroma Thylakoid lumen Photosystem II RubisCO H + H + ATP NADP + O 2 H 2 O H...
Redox regulation Light Light Nucleus Cytosol N-phase Chloroplast stroma CO 2 CH 2 O Allen JF (2003) The function of genome...
Co -location   for  R edox   R egulation   -   CoRR  Prediction: Explanation of previous knowledge Distribution of genes f...
Lecture 5  Co-location for Redox Regulation
Upcoming SlideShare
Loading in...5
×

Why do chloroplasts and mitochondria have genomes?

822

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
822
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
25
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Why do chloroplasts and mitochondria have genomes?"

  1. 2. Lectures by John F. Allen School of Biological and Chemical Sciences, Queen Mary, University of London Cell Biology and Developmental Genetics 1 jfallen.org
  2. 3. Cell Biology and Developmental Genetics Lectures by John F. Allen Endosymbiosis and the origin of bioenergetic organelles. Some history Endosymbiosis and the origin of bioenergetic organelles. A modern view Mitochondria as we know them and don't know them Why do chloroplasts and mitochondria have genomes? Co-location for Redox Regulation Mitochondria, ageing, and sex – energy versus fidelity
  3. 4. Cell Biology and Developmental Genetics Lectures by John F. Allen Slides and supplementary information: jfallen.org/lectures
  4. 5. School of Biological and Chemical Sciences Seminars WEDNESDAYS AT 12 NOON IN G23, G. E. FOGG BUILDING 3 February 2010 Dr Nick Lane Provost’s Venture Research Fellow, University College London Life Ascending. The Ten Great Inventions of Evolution
  5. 6. Lecture 4 Why do chloroplasts and mitochondria have genomes?
  6. 7. I II III IV ATPase Mitochondrial matrix Inter-membrane space
  7. 8. Chloroplast stroma Thylakoid lumen Cyt b 6 - f Photosystem I ATPase Photosystem II RubisCO
  8. 9. Problem Why Do Mitochondria and Chloroplasts Have Their Own Genetic Systems? Why do mitochondria and chloroplasts require their own separate genetic systems when other organelles that share the same cytoplasm, such as peroxisomes and lysosomes, do not? …. The reason for such a costly arrangement is not clear, and the hope that the nucleotide sequences of mitochondrial and chloroplast genomes would provide the answer has proved unfounded. We cannot think of compelling reasons why the proteins made in mitochondria and chloroplasts should be made there rather than in the cytosol. Molecular Biology of the Cell © 1994 Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson Molecular Biology of the Cell, 3rd edn. Garland Publishing
  9. 10. Proposed solutions (hypotheses) There is no reason. “That’s just how it is”. (Anon) The “Lock-in” hypothesis. (Bogorad, 1975). In order for core components of multisubunit complexes to be synthesised, de novo, in the correct compartment. The evolutionary process of transfer of genes from organelle to nucleus is still incomplete. E.g. Herrmann and Westhoff, 2001: The partite plant genome is not in a phylogenetic equilibrium. All available data suggest that the ultimate aim of genome restructuring in the plant cell, as in the eukaryotic cell in general, is the elimination of genome compartmentation while retaining physiological compartmentation . The frozen accident. The evolutionary process of gene transfer was underway when something happened that stopped it. E.g. von Heijne, 1986. It’s all a question of hydrophobicity. The five-helix rule. (Anon) Some proteins (with co-factors) cannot be imported. (Anon) Co -location for R edox R egulation - CoRR (Allen 1993, 2003 et seq .) Why Do Mitochondria and Chloroplasts Have Their Own Genetic Systems?
  10. 11. Proposed solution (hypothesis) Why Mitochondria and Chloroplasts Have Their Own Genetic Systems Allen, J. F. (1993) J. Theor. Biol. 165, 609-631 Allen, J. F. (2003) Phil. Trans. R. Soc. B458, 19-38 Co -location for R edox R egulation - CORR Vectorial electron and proton transfer exerts regulatory control over expression of genes encoding proteins directly involved in, or affecting, redox poise. This regulatory coupling requires co-location of such genes with their gene products; is indispensable; and operated continuously throughout the transition from prokaryote to eukaryotic organelle. Organelles “make their own decisions” on the basis of environmental changes affecting redox state.
  11. 12. Bacterium Endosymbiont Bioenergetic organelle
  12. 13. 1. As now generally agreed, bioenergetic organelles evolved from free-living bacteria. 2. Gene transfer between the symbiont or organelle and the nucleus may occur in either direction and is not selective for particular genes. 3. There is no barrier to the successful import of any precursor protein, nor to its processing and assembly into a functional, mature form. 4. Direct redox control of expression of certain genes was present in the bacterial progenitors of chloroplasts and mitochondria, and was vital for cell function before, during, and after the transition from bacterium to organelle. The mechanisms of this control have been conserved. 5. For each gene under redox control, it is selectively advantageous for that gene to be retained and expressed only within the organelle. 6. For each bacterial gene that survives and is not under redox control, it is selectively advantageous for that gene to be located in the nucleus and expressed only in the nucleus and cytosol. If the mature gene product functions in chloroplasts or mitochondria, the gene is first expressed in the form of a precursor for import. 7. For any species, the distribution of genes between organelle and nucleus is the result of selective forces that continue to operate. 8. Those genes for which redox control is always vital to cell function have gene products involved in, or closely connected with, primary electron transfer. These genes are always contained within the organelle. 9. Genes whose products contribute to the organelle genetic system itself, or whose products are associated with secondary events in energy transduction, may be contained in the organelle in one group of organisms, but not in another. 10. Components of the redox-signalling pathways upon which co-location for redox regulation depends are themselves not involved in primary electron transfer, and so their genes have been relocated to the nucleus. Co -location for R edox R egulation - CoRR Ten assumptions, axioms, principles jfallen.org/corr
  13. 14. Co -location for R edox R egulation - CoRR Prediction: Explanation of previous knowledge Distribution of genes for components of oxidative phosphorylation between mitochondria and the cell nucleus Prediction: Experimental results Redox control of mitochondrial and chloroplast gene expression Prediction: Experimental results Persistence of “bacterial” redox signalling components in chloroplasts and mitochondria
  14. 15. Co -location for R edox R egulation - CoRR Prediction Explanation of previous knowledge Distribution of genes for components of oxidative phosphorylation between mitochondria and the cell nucleus
  15. 16. Redox regulation
  16. 17. Redox regulation Nucleus Cytosol N-phase Mitochondrial matrix O 2 H 2 O
  17. 18. I II III IV ATPase Mitochondrial matrix Inter-membrane space
  18. 19. I II III IV ATPase Mitochondrial matrix Inter-membrane space H + H + NADH O 2 ATP ADP H 2 O NAD + succinate fumarate H + H +
  19. 20. Redox regulation Nucleus Cytosol N-phase Mitochondrial matrix O 2 H 2 O Allen JF (2003) The function of genomes in bioenergetic organelles Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 358: 19-37
  20. 21. Co -location for R edox R egulation - CORR Prediction Explanation of previous knowledge Distribution of genes for components of photosynthetic phosphorylation between chloroplasts and the cell nucleus
  21. 22. Redox regulation
  22. 23. Redox regulation Light Light Nucleus Cytosol N-phase Chloroplast stroma CO 2 CH 2 O
  23. 24. Chloroplast stroma Thylakoid lumen Cyt b 6 - f Photosystem I ATPase Photosystem II RubisCO
  24. 25. Cyt b 6 - f Photosystem I ATPase Chloroplast stroma Thylakoid lumen Photosystem II RubisCO H + H + ATP NADP + O 2 H 2 O H + H + H + ADP NADPH ATP ADP H 2 O O 2 NADP + NADPH H + H +
  25. 26. Redox regulation Light Light Nucleus Cytosol N-phase Chloroplast stroma CO 2 CH 2 O Allen JF (2003) The function of genomes in bioenergetic organelles Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 358: 19-37
  26. 27. Co -location for R edox R egulation - CoRR Prediction: Explanation of previous knowledge Distribution of genes for components of oxidative phosphorylation between mitochondria and the cell nucleus Prediction: Experimental results Redox control of mitochondrial and chloroplast gene expression Prediction: Experimental results Persistence of “bacterial” redox signalling components in chloroplasts and mitochondria
  27. 28. Lecture 5 Co-location for Redox Regulation
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×