Math models reveal 'molten' and 'glassy' states of RNA

From: Amara Graps (amara@amara.com)
Date: Thu May 08 2003 - 10:58:18 MDT

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     From Scientific Computing Newsline
    Issue 63 April 2003
    http://scnewsline.campublishers.com

    Mathematical models reveal 'molten' and 'glassy' states of RNA

    Mathematical models have given physicists a new look at DNA's
    chemical counterpart, RNA. The models - showing that RNA behaves
    differently depending on the temperature of its environment - may
    help biologists better understand how life evolved on Earth.

    The models suggest that high temperatures give twisted strands of RNA
    the flexibility to fold into many different shapes, while low
    temperatures cause it to collapse into a single shape. Exactly how
    RNA folds into any particular shape is a mystery. Other researchers
    have tried to tackle the problem with computer simulations, by
    calculating the possible formations that result from a certain number
    of base units coming together. But simulating realistic RNA molecules
    - that is, very long RNA strands with many base units - is difficult.

    Bundschuh and Terence Hwa of the University of California, San Diego,
    examined the problem differently. They have developed the first
    mathematical theory for the possible states of an RNA molecule. These
    mathematical models show that high temperatures cause RNA to enter a
    flexible state in which it can take on a variety of configurations.
    The flexible state is known as the 'molten' state. When temperatures
    fall too low, the RNA enters a tangled, or 'glassy', state.

    The results hold implications for the study of the related 'protein
    folding problem'. The work also has broader relevance for
    evolutionary biology, where experts have speculated that early life
    might have relied exclusively upon RNA. 'RNA could in fact be a
    stepping-stone to today's world of DNA. DNA cannot replicate without
    proteins, and proteins cannot be produced without RNA,' Bundschuh
    said. 'You could say we're characterising what evolution is up
    against.'
    http://www.ucsd.edu/

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