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Journal of Molecular Evolution

, Volume 50, Issue 4, pp 313–323 | Cite as

From Amino Acid Landscape to Protein Landscape: Analysis of Genetic Codes in Terms of Fitness Landscape

  • Takuyo  Aita
  • Satoshi  Urata
  • Yuzuru  Husimi
  • 84 Downloads

Abstract.

Assigning the values of a certain physicochemical property for individual amino acids to the corresponding codons, we can make an amino acid property ``landscape'' on a four valued three dimensional sequence space from a genetic code table. Eleven property landscapes made from the standard genetic code (SGC) were analyzed. The evaluation of correlation for each landscape is done by θ value, which represents the ratio of the mean slope (as an additive term) to the degree of roughness (as a nonadditive term). The θ-values for hydropathy indices, polarity, specific heat, and β-sheet propensity were considerably large with respect to SGC. This implies that the additivity of the contribution from each letter holds for these properties. To clarify the meaning of the so-called mutational robustness of SGC, we next examined correlations between the amino acid property and the actual ``site fitnesses'' of a protein. The site fitnesses were derived from a set of binding preference scores of amino acid residues at every site in MHC class I molecule binding peptides (Udaka et al. in press). We found that the SGC's θ value for an amino acid property is correlated with the significance of the property in the protein function. Adaptive walk simulation on fitness (= affinity) landscapes in a base sequence space for these model peptides confirmed better evolvability due to the introduction of SGC.

Key words: Standard genetic code — Mutational robustness — Evolvability — Adaptive walk — Codon — Evolutionary molecular engineering 

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Copyright information

© Springer-Verlag New York Inc. 2000

Authors and Affiliations

  • Takuyo  Aita
    • 1
  • Satoshi  Urata
    • 1
  • Yuzuru  Husimi
    • 1
  1. 1.Department of Functional Materials Science Saitama University Urawa 338, JapanJP

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