Horizontal Gene Transfer and the Last Universal Common Ancestor •
The Open University • 5th and 6th September 2013
Coupling between information
processing and redox chemistry.
Cellular co-location of energy
transduction with genome function
John F. Allen
School of Biological and Chemical Sciences, Queen Mary University of London
and Research Department of Genetics, Evolution and Environment, University College London
1
http://en.wikipedia.org/wiki/Geologic_time_scale
LUCA here seems to mean:
The Last Common Ancestor of all things alive today...
...therefore Horizontal Gene Transfer could have occurred between LUCA
and things now no longer alive
What do we mean by LUCA...?
A. The Last Common Ancestor of all things alive
today (on Earth)...
B. The Last Common Ancestor of all things that
have ever lived (on Earth)...
This tree diagram, used to show the divergence of species, is the only illustration in the Origin of Species.
http://en.wikipedia.org/wiki/On_the_Origin_of_Species
LUCA here must mean:
B. The Last Common Ancestor
of all things that have ever
lived...
...in which case...
• With what did LUCA engage in
Horizontal Gene Transfer...?
• Can any sensible distinction be made
between LUCA’s Horizontal and Vertical
Gene Transfer...?
• Can Horizontal Gene Transfer have
played any part in the Origin of Life?
Coupling between information
processing and redox chemistry.
Electron transport – chains of coupled oxidation
and reduction reactions
Coupling between information
processing and redox chemistry.
Homeostasis...
...the maintenance of a constant internal
environment despite changes in the external
environment.
A block diagram for feedback. The feedback is negative if B < 0
http://en.wikipedia.org/wiki/Feedback
Coupling between information
processing and redox chemistry.
Redox Homeostasis...
...the maintenance of a constant electrochemical potential
and ionic concentration gradient across a cellular boundary,
despite changes in the electrochemical potential of the
external environment and despite changing identities and
activities of electron donors and acceptors.
Allen JF (2010) Journal of Cosmology, 10, 3362-3373
A feedback loop involving the elements of a redox repressor or activator
incorporating an iron-sulphur centre in a polypeptide
Allen J. F. (2010) Journal of Cosmology, 10, 3362-3373
A feedback loop involving the elements of a two-component redox
regulatory system
Allen J. F. (2010) Journal of Cosmology, 10, 3362-3373
A. The proton motive force across the boundary
of LUCA. The pmf is made by an alkaline (high
pH) internal effluent from LUCA's founding
hydrothermal vent and by an acidic (low pH)
external environment of carbonic acid solution.
B. The proton motive force of living cells
descended from LUCA. The pmf is made by an
alkaline (high pH) cytoplasm and by an acidic (low
pH) extracellular environment. The gradient is
continuously replenished by electrons flowing
across the membrane from donors to acceptors.
Nick Lane, John F. Allen and William Martin (2010)
How did LUCA make a living? Chemiosmosis in the origin of life. Bioessays 32: 271-280
Steps from a porous inorganic metal-sulphide vesicle to a free-living cell.
A. Hydrothermal fluid is alkaline, in contrast to the acidic ocean into which it flows through the
boundary of a porous, catalytic, metal sulphide vesicle.
Steps from a porous inorganic metal-sulphide vesicle to a free-living cell.
B. The porosity of the vesicle is decreased by the intrusion of products of autocatalytic carbon reduction,
symbolized by the cycle of carbon. The boundary of the vesicle begins to sustain a small gradient of hydrogen
ion concentration and electrical potential difference: positive (P-phase) outside; negative (N-phase) inside.
Steps from a porous inorganic metal-sulphide vesicle to a free-living cell.
C. The porosity decreases further. A mechanism of negative feedback interrupts proton influx, and
an active transport drives proton efflux.
Steps from a porous inorganic metal-sulphide vesicle to a free-living cell.
D. The vesicle is now formed from the organic intrusion alone, which presents a sufficient barrier to
proton influx for the active proton efflux to generate and sustain a proton motive force. The
dependency on hydrothermal fluid is lost, along with the inorganic container, though remnants of the
latter remain to support vectorial electron and proton translocation.
Steps from a porous inorganic metal-sulphide vesicle to a free-living cell.
Allen JF (2010) Redox homeostasis in the emergence of life. On the constant internal
environment of nascent living cells. Journal of Cosmology, 10, 3362-3373
Coupling between information
processing and redox chemistry.
Cellular co-location of energy
transduction with genome function
Photosynthesis and respiration
N
–ve
P
+ve
N
–ve
P
+ve
P
+ve
N
–ve
After: David S. Goodsell (1993) The
Machinery of Life. Springer
N
–ve
P
+ve
P
+ve
N
–ve
Allen, J. F. (1993) Control of Gene Expression by Redox Potential and the Requirement for
Chloroplast and Mitochondrial Genomes. Journal of Theoretical Biology, 165, 609-631
Coupling between information
processing and redox chemistry.
Cellular co-location of energy
transduction with genome function
Co-location for Redox Regulation
Allen, J. F. (2003) The function of genomes in bioenergetic
organelles. Philosophical Transactions of the Royal Society of
London Series B-Biological Sciences, 358, 19-37
jfallen.org/corr
Allen J. F., de Paula W. B. M., Puthiyaveetil S. & Nield J. (2011) Trends in Plant Science 16(12), 645-655
Coupling between information
processing and redox chemistry.
Cellular co-location of energy
transduction with genome function
The Redox Switch Hypothesis for
the first cyanobacterium and for
the origin of oxygenic
photosynthesis
Allen J. F. (2005) A redox switch hypothesis for the origin of two light reactions in photosynthesis. FEBS Letters 579: 963-968
Archean landscape by Peter Sawyer of the Smithsonian Institution
Phanerozoic Landscape
Stromatolites at Hamelin Pool, Western Australia
Photograph 4 October 2007 by Catherine Colas des Francs-Small, The University of Western Australia
Policeman Point, Coorong Lagoon, South Australia
Photograph 9 March 2009 by the author
Policeman Point, Coorong Lagoon, South Australia
Photograph 9 March 2009 by the author
Dietrich, L.E.P., Tice, M.M. and Newman, D.K. (2006) The co-evolution of life and Earth. Current Biology 16, R396-R400
http://en.wikipedia.org/wiki/Geologic_time_scale
Coupling between information
processing and redox chemistry.
Cellular co-location of energy
transduction with genome function
Acknowledgements...
1
William Martin
Heinrich-Heine-Universität Düsseldorf
Nick Lane
University College London
Michael Russell
NASA-JPL, California Institute of Technology
John Raven
University of Dundee
Liang Wang • John Allen • Noor Agip • Iskander Ibrahim • Wilson de Paula
August 29, 2013
(↑). The Earth–Moon system photographed from the Cassini orbiter, Saturn. July 19, 2013.
NASA/JPL-Caltech/Space Science Institute.
Horizontal Gene Transfer and the Last Universal Common Ancestor •
The Open University • 5th and 6th September 2013
Thank you for your
attention.
http://jfallen.org