Download The Cold Never Bothered Me Anyway Measuring the Forces at Work

The Cold Never Bothered Me Anyway
Measuring the Forces at Work
Defending Protein-DNA Interactions
from Temperature Extremes.
K. Ellen Kendrick*†, David J. Brockwell†, Lorna Dougan*†
*Molecular and Nanoscale Physics Group, University of Leeds
†Astbury Centre for Structural Molecular Biology, University of Leeds
Extremophilic Proteins
Psychrophile
Optimum Temperature
10 °C
Measuring Protein Mechanics
The Mechanical properties of proteins can be measured
using an Atomic Force Microscope. This uses the deflection of
a small cantilever to measure piconewton forces and can be
utilised to pull apart proteins one molecule at a time. The
force required to unfold a protein indicates it’s stability, and
this method can be used to measure other mechanical data.
need flexibility to
bind
King George island, Antarctica
Life has been found across the planet in conditions that vary
greatly in temperature, acidity, salinity and aridity. Proteins
are the molecules that do the work in keeping cells alive, so
to survive in extreme conditions these proteins need to be
adapted. These adaptations adjust the forces that hold the
molecules together. The proteins are then able to carry out
the processes essential to cell survival. This includes the
fundamental mechanism of interactions between proteins
and the nucleic acids, DNA and RNA.
Mesophile
Optimum Temperature
37 °C
Performing this unfolding experiment in the presence and absence of
single stranded DNA (ssDNA) we can explore the properties
that allow it to function at specific temperatures. Flexibility is key for
binding, and measurements so far have shown an increase in flexibility
when ssDNA is bound to the mesophilic cold shock protein.
Combining this with Nuclear Magnetic Resonance experiments,
another way to measure flexibility, we plan to compare the
DNA needs to constantly be copied,
psychrophilic and mesophilic Cold Shock Protein for clues as to
repaired and read for healthy growth
and reproduction. Any mistakes have the how the psychrophilic protein functions at lower temperatures.
Temperate Soils
The Cold Shock Protein has been
identified in many organisms from
various environments. This protein binds
to nucleic acids when there is a drop in
temperature and is thought to help
maintain protein production. It has a
highly conserved structure but small
differences in the amino acid sequence
of extremophilic Cold Shock proteins
change their flexibility, allowing them to
move about and operate at the
environment temperature of the
organism. This is one of the reasons they
have been chosen as model proteins to
explore how these adaptations are
encoded at the molecular level.
Protein-DNA
Interactions
Cold
temperatures
can cause
nucleic acids to
fold into
shapes that
cannot be read.
Applications
potential to cause huge problems for
the organism. Much of this work
is carried out by proteins.
Proteins as Building Blocks
Protein based hydrogels are exciting new
Protein based
Hydrogel Structure materials being explored for biomedical and
Cold Shock
Proteins bind to
nucleic acids to
keep them from
folding incorrectly.
1nm
Understanding protein evolution
Hyperthermophile
Hydrothermal vents, e.g. Vulcano, Italy
Optimum Temperature
80 °C
biotechnological applications, with the
potential for smart materials which
10mm
respond to external stimuli.
These hydrogels could be
applied to wound healing,
targeted drug delivery and
have the advantage of being biocompatible.
Mechanically and thermally stable proteins
are required for this application.
Understanding extremophiles helps
us appreciate how life may have
evolved in past climates. It also
exposes the limits of what can be
survived, which may aid the search
for life outside our planet.
Acknowledgements
We are grateful to the White Rose University Consortium and
European Research Council for funding and to the rest of the
Dougan group for useful discussions and support.