Enzyme-Driven Speciation: Crystallizing Archaea via Lipid Capture |
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Authors: | Jian Payandeh " target="_blank">Emil F Pai |
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Institution: | (1) Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada;(2) Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada;(3) Department of Molecular & Medical Genetics, University of Toronto, Toronto, Ontario, Canada;(4) Division of Cancer Genomics & Proteomics, Ontario Cancer Institute, MaRS Centre, Toronto Medical Discovery Tower, Toronto, Ontario, M5G 1L7, Canada |
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Abstract: | As the origin(s) of life on Earth remains an open question, detailed characteristics about the “last universal ancestor” (LUA)
continue to be obscured. Here we provide arguments that strengthen the bacterial-like nature of the LUA. Our view attempts
to recreate the evolution of archaeal lipids, the major components of the distinctive membrane that encapsulates these ancient
prokaryotes. We show that (S)- 3-O-geranylgeranylglyceryl phosphate synthase (GGGPS), a TIM-barrel protein that performs the committed step in archaeal lipid
synthesis, likely evolved from the duplication and fusion of a (βα)4 half-barrel ancestor. By comparison to the well-characterized HisA and HisF TIM-barrel proteins, we propose a time line for
the invention of this diagnostic archaeal biosynthetic pathway. After excluding the possibility of horizontal gene transfer,
we conclude that the evolutionary history of GGGPS mirrors the emergence of Archaea from the LUA. We illustrate aspects of
this “lipid capture” model that support its likelihood in recreating key evolutionary events and, as our hypothesis is built
on a single initiating event, we suggest that the appearance of GGGPS represents an example of enzyme-driven speciation.
Reviewing Editor: Dr. Niles Lehman |
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Keywords: | Speciation Archaeal evolution Enzyme recruitment Last universal ancestor Membrane lipids |
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