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Science Forum Index » Bio Evolution Forum » News: Protein 'Shocks' Evolution Into Action
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| Robert Karl Stonjek |
 Posted: Thu Feb 28, 2008 8:49 am |
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Protein 'Shocks' Evolution Into Action
ScienceDaily (Feb. 27, 2008) - Heat shock protein 90 (HSP90) has a greater
impact on the appearance of new traits than previously expected, according
to two articles published on February 26 in the Proceedings of the National
Academy of Science (PNAS) by researchers in Whitehead Member Susan
Lindquist's lab and their colleagues in Christine Queitsch's lab at Harvard
University's FAS Center for Systems Biology.
"One of the great mysteries of biology is how life could have evolved so
rapidly," says Lindquist. "This research gives at least one plausible
explanation for the speed of evolution and for the evolution of complex
traits affected by several genes."
HSP90 belongs to a class of proteins called chaperones, which help other
proteins in the cell fold properly, prevent protein clumping, and escort
improperly made proteins to be recycled. These vital functions become even
more important when a cell is stressed by heat, cold, toxins or other
hardships that affect protein folding.
Hsp90 is particularly interesting because it is specialized to chaperone
proteins that are key regulators of growth and development. Thus, it is in a
position to couple environmental change to the release of hidden genetic
variation and thereby to produce a host of new traits. Selective breeding
can lead to the enrichment of those genetic changes, allowing the trait to
be inherited even in the absence of stress.
"In previous studies, most of the new traits that appeared in response to
stress would have been detrimental to the organism - hopeful monsters," says
Lindquist.
In the current studies, Todd Sangster and his co-authors used inbred mustard
plants (Arabidopsis thaliana) and simulated stress by inhibiting their HSP90
production with the chemical geldanamycin, a known, highly specific HSP90
inhibitor or by RNAi. The authors then examined the effects of stressing the
plants. When the plants were grown without geldanamycin, HSP90 suppressed
the mutant proteins, so their effects were not observed and the plant
appeared normal.
However, when the plants were slightly stressed by geldanamycin,
HSP90-related traits emerged; seedling stem and root length increased,
flowering time was delayed and size and fitness were altered. The abundance
of naturally occurring genetic variation that is affected by Hsp90 was
remarkable. The authors also genetically mapped the traits that could be
affected by HSP90 and found that nearly every complex trait in A. thaliana
that they investigated could be affected by HSP90-dependent genetic
variation.
"One stressful event can affect many traits and allow previously unseen
genetic variation to be expressed," says Sangster. "We don't know yet what
is going on at the molecular level-why the HSP90-dependent traits are
expressed when the plants are mildly stressed."
Future research could include mapping HSP90-dependent traits and determining
how this interaction between HSP90 and the mutant trait proteins at the
molecular level.
Funding was provided by the Howard Hughes Medical Institute, the Mathers
Foundation, the NIGMS grant for National Centers for Systems Biology, and
the Bauer Fellowship.
Susan Lindquist's primary affiliation is with Whitehead Institute for
Biomedical Research, where her laboratory is located and all her research is
conducted. She is also professor of biology at Massachusetts Institute of
Technology and an Investigator of the Howard Hughes Medical Institute.
Whitehead Institute for Biomedical Research is a nonprofit, independent
research and educational institution. Wholly independent in its governance,
finances and research programs, Whitehead shares a close affiliation with
Massachusetts Institute of Technology through its faculty, who hold joint
MIT appointments.
Full citation:
PNAS, February 26, 2008, 105 (7) "HSP90 affects the expression of genetic
variation and developmental stability in quantitative traits" Todd A.
Sangster (1,2), Neeraj Salathia (3), Soledad Undurraga (3), Kurt
Schellenberg (3), Susan Lindquist (1), and Christine Queitsch (3)
1.. Committee on Genetics, University of Chicago
2.. Whitehead Institute for Biomedical Research
3.. FAS Center for Systems Biology, Harvard University
PNAS, February 26, 2008, 105 (7) "HSP90-Buffered Genetic Variation is Common
in Arabidopsis thaliana" Todd A. Sangster (1,2), Neeraj Salathia (3), Hana
N. Lee (3), Etsuko Watanabe (3), Kurt Schellenberg (3), Keith Morneau (3),
Hui Wang (3), Soledad Undurraga (3) , Christine Queitsch (3) and Susan
Lindquist (1)
1.. Committee on Genetics, University of Chicago
2.. Whitehead Institute for Biomedical Research, Howard Hughes Medical
Institute
3.. FAS Center for Systems Biology, Harvard University
Adapted from materials provided by Whitehead Institute for Biomedical
Research.
Whitehead Institute for Biomedical Research (2008, February 27). Protein
'Shocks' Evolution Into Action. ScienceDaily. Retrieved February 28, 2008,
from http://www.sciencedaily.com/releases/2008/02/080223123054.htm
Posted by
Robert Karl Stonjek |
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