title: On the origin of protein superfamilies and superfolds.
abstract: Distributions of protein families and folds in genomes are highly skewed, having a small number of prevalent superfamiles/superfolds and a large number of families/folds of a small size. Why are the distributions of protein families and folds skewed? Why are there only a limited number of protein families? Here, we employ an information theoretic approach to investigate the protein sequence-structure relationship that leads to the skewed distributions. We consider that protein sequences and folds constitute an information theoretic channel and computed the most efficient distribution of sequences that code all protein folds. The identified distributions of sequences and folds are found to follow a power law, consistent with those observed for proteins in nature. Importantly, the skewed distributions of sequences and folds are suggested to have different origins: the skewed distribution of sequences is due to evolutionary pressure to achieve efficient coding of necessary folds, whereas that of folds is based on the thermodynamic stability of folds. The current study provides a new information theoretic framework for proteins that could be widely applied for understanding protein sequences, structures, functions, and interactions.
authors.affiliation: Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Abram
authors.initials: A
authors.lastname: Magner
authors.affiliation: Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Szpankowski
authors.affiliation: 1] Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA [2] Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kihara
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D008962:Models, Theoretical; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D011506:Proteins