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SUMMARY:In the beginning it was dark: Hydrothermal vents and the origin of
  life (real microbes)  - William Martin\, Universität Düsseldorf
DTSTART:20151126T161500Z
DTEND:20151126T171500Z
UID:TALK59508@talks.cam.ac.uk
CONTACT:Scientific Meetings Co-ordinator
DESCRIPTION:Life is a chemical reaction. Since life arose\, the same exerg
 onic reaction has persisted in uninterrupted continuity right up into this
  seminar. Life harnesses existing redox couples in such a way that energy 
 is conserved within compartments that are insulated\, but not isolated\, f
 rom the environment\, while carbon and nitrogen are assimilated in such a 
 way that more the energy harnessing system ultimately accrues. The talk ou
 tlines an energetically feasible path from one\, specific hydrothermal set
 ting for the origin of life to the first free-living cells. The sources of
  energy available to early organic synthesis\, early evolving systems and 
 early cells stand in the foreground\, as do the possible mechanisms of the
 ir conversion into harnessable chemical energy for synthetic reactions. Wi
 th regard to the possible temporal sequence of events\, the talk will focu
 s on: (i) alkaline hydrothermal vents as the far-from-equilibrium setting\
 , (ii) the Wood-Ljungdahl (acetyl-CoA) pathway as the route that could hav
 e underpinned carbon assimilation for these processes\, (iii) biochemical 
 divergence\, within the naturally formed inorganic compartments at a hydro
 thermal mound\, of geochemically confined replicating entities with a comp
 lexity below that of free-living prokaryotes\, and (iv) acetogenesis and m
 ethanogenesis as the ancestral forms of carbon and energy metabolism in th
 e first free-living ancestors of the eubacteria and archaebacteria\, respe
 ctively. In terms of the main evolutionary transitions in early bioenerget
 ic evolution\, the talk will focus on: (i) thioester-dependent substrate-l
 evel phosphorylations\, (ii) harnessing of naturally existing proton gradi
 ents at the vent-ocean interface via the ATP synthase\, (iii) harnessing o
 f Na+ gradients generated by H+/Na+ antiporters\, (iv) flavin-based bifurc
 ation-dependent gradient generation\, and finally (v) quinone-based (and Q
 -cycle-dependent) proton gradient generation. Of those five transitions\, 
 the first four are posited to have taken place at the vent. Ultimately\, a
 ll bioenergetic processes (hence all life) depend\, even in today's ecosys
 tems\, upon low-potential ferredoxins that reduce CO2. That is a very impo
 rtant observation. Reduced ferredoxin stems in turn either from electron b
 ifurcation or chemiosmosis. At life's origin\, a reaction of the type\n\nr
 educed iron -> reduced carbon\n\nprobably stood at the very beginning of b
 ioenergetic processes\, hence evolution.
LOCATION:Max Perutz Lecture Theatre\, Medical Research Council (MRC) (MRC 
 Laboratory of Molecular Biol
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