Scheduled Seminars on 2/7/2013

Igor Berezovsky at 11:00  Edit  Reschedule  Delete
Affiliation: Weizmann Institute of Science
Host: Anna Panchenko

GC hysteresis describes the fundamental tradeoff between the nucleotide and amino acid composition in prokaryotes
Despite considerable progress in our understanding of selective forces in the evolution and molecular mechanisms of adaptation, the very basics of the tradeoff between the nucleotide and amino acid compositions are yet to be determined. Mutations in nucleotide sequences are the origin of genetic variability, and selection is the driving force of evolution and molecular adaptation. In protein-coding sequences synonymous mutations are a source of codon bias, and non-synonymous ones change amino acids. We discovered that there is an optimal tradeoff between them, which is described by the nonlinear and ambiguous relationship between the composition of nucleic and amino acids, the GC hysteresis. We show why the genomes follow the GC hysteresis, describe factors that shape it, and suggest an analytical model for predicting amino acid composition from the genomic GC content.

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