prokaryote evolution and globin proteins

Ken Kinman kinman at HOTMAIL.COM
Tue Oct 22 03:59:30 CDT 2002


Dear All,
      It's been a couple of years since I've delved seriously into
prokaryotic evolution, so maybe it is time I caught up a little.  It seems
that myoglobin-type genes have been discovered in both eubacteria and
metabacteria (aka "Archaebacteria").
      SCIENTIFIC PREDICTION.  Workers at the University of Hawaii have
concluded that such genes are ancient based on their discovery in
Metabacteria.  However, I would go even further and predict that some
cyanobacteria will contain the most primitive myoglobin genes of all, and
that alpha and beta hemoglobin genes evolved separately in different
bacterial lineages.  The genes for alpha or beta globin genes were then
united by horizontal transfer to create hemoglobin.
     Whether this occurred in a cyanobacterium originally, or occurred in a
eukaryote and transferred back to certain cyanobacteria is anybody's guess.
In any case, the split between globin and chlorophyll genes is quite
ancient.
     And contrary to what the University of Hawaii scientists state,
molecular oxygen was probably present 3.5 billion years ago.  Not in the
atmosphere (where it would only accumulate much much later), but within the
layers of stromatolites.  Photosynthesis is truly ancient, and the
Metabacteria of present deep-sea vents are most likely tapping into the
energy of ancient photosynthetic products that have been subducted and
slowly being recycled

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