[pccgrads] Betul Kacar on "Reconstructed enzymes as proxies for ancient biogeochemical intermediaries" Tue 11/27 at 3

UW Program On Climate Change uwpcc at uw.edu
Mon Nov 26 13:24:31 PST 2018


*UW Astrobiology Colloquium, Tuesday November 27th at 3:00 PM*

*Location:* Physics & Astronomy Auditorium (PAA) Room A118

*Speaker*: Betul Kacar, Professor of Astrobiology at the University of

*Title*: Reconstructed enzymes as proxies for ancient biogeochemical

Two datasets, the geologic record and the genetic content of extant
organisms, provide complementary insights into the history of how key
molecular components have shaped or driven global environmental and
macroevolutionary trends. Changes in global physicochemical modes over time
are thought to be a consistent feature of this relationship between Earth
and life, as life is thought to have been optimizing protein functions for
the entirety of its ~3.8 billion years of history on Earth. Organismal
survival depends on how well critical genetic and metabolic components can
adapt to their environments, reflecting an ability to optimize efficiently
to changing conditions. The geologic record provides an array of
biologically independent indicators of macroscale atmospheric and oceanic
composition, but provides little in the way of the exact behavior of the
molecular components that influenced the compositions of these reservoirs.
By reconstructing sequences of proteins that might have been present in
ancient organisms, we can downselect to a subset of possible sequences that
may have been optimized to these ancient environmental conditions. How can
one use modern life to reconstruct ancestral behaviors? Configurations of
ancient sequences can be inferred from the diversity of extant sequences,
and then resurrected in the lab or in modern host organisms to ascertain
their biochemical attributes. Here I present a novel approach, where the
focus of the study is not just the sequence diversity of past proteins but
the diversity and evolution of protein functionality. This functionality is
evaluated in the context of geology's convoluted record of a multiplicity
of enzyme functions acting upon environmental reservoirs over time.
Studying the interface of past molecular behavior and environmental
conditions may yield new insights into the interpretation of deep time
biosignatures, as expressed by the impact of organismal optima on
metabolites and fossil remains.
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