Restricted evolution of proteins

From: pruest@pop.dplanet.ch
Date: Wed Nov 08 2000 - 11:09:41 EST

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    > >The following paper is very important in connection with protein evolvability: Douglas D. Axe...J.Mol.Biol. 301 (2000), 585-95.
    > >Axe's abstract: "... This is found to cause complete loss of function in vivo ..."
    > >
    > >This shows that previous estimates of the number of different possible sequences that might show a given biological activity, such as H.P. Yockey's ("Information theory and molecular biology" (Cambridge: Cambridge Univ.Press, 1992), p.254), are likely to be vast overestimates because they neglect possible interdependencies between different amino-acid positions...
    >
    > Not necessarily. Axe looked at the function of the modified proteins in vivo. Such large numbers of changes are unlikely to happen all at once in real organisms, so that coevolution of associated proteins is possible. As an example, mitochondrial rDNA genes do not even use the same genetic code as nuclear rDNA genes, so they cannot be interchanged, yet both successfully perform the same function
    >
    > Dr. David Campbell

    I did not claim there could not be any possible evolutionary path, but
    that the number of possibly active RANDOM sequences had been vastly
    overestimated. For darwinian evolution, this is irrelevant IF there is
    at least one feasible path. But it makes a huge difference for the
    success of random mutational paths not under selection, e.g. when a new
    function emerges in a pseudogene or other cryptic state.

    Peter Ruest <pruest@dplanet.ch>



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