title: A Dynamic Model for the Evolution of Protein Structure.
abstract: Domains are folded structures and evolutionary building blocks of protein molecules. Their three-dimensional atomic conformations, which define biological functions, can be coarse-grained into levels of a hierarchy. Here we build global dynamical models for the evolution of domains at fold and fold superfamily (FSF) levels. We fit the models with data from phylogenomic trees of domain structures and evaluate the distributions of the resulting parameters and their implications. The trees were inferred from a census of domain structures in hundreds of genomes from all three superkingdoms of life. The models used birth-death differential equations with the global abundances of structures as state variables, with one set of equations for folds and another for FSFs. Only the transitions present in the tree are assumed possible. Each fold or FSF diversifies in variants, eventually producing a new fold or FSF. The parameters specify rates of generation of variants and of new folds or FSFs. The equations were solved for the parameters by simplifying the trees to a comb-like topology, treating branches as emerging directly from a trunk. We found that the rate constants for folds and FSFs evolved similarly. These parameters showed a sharp transient change at about 1.5 Gyrs ago. This time coincides with a period in which domains massively combined in proteins and their arrangements distributed in novel lineages during the rise of organismal diversification. Our simulations suggest that exploration of protein structure space occurs through coarse-grained discoveries that undergo fine-grained elaboration.
authors.affiliation: Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois, Urbana, IL, 61801, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Tal
authors.affiliation: Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois, Urbana, IL, 61801, USA.|Department of Cell and Developmental Biology, University of Illinois, Urbana, IL, 61801, USA.|Department of Mathematics, University of Illinois, Urbana, IL, 61801, USA.|Innovation Center for Biomedical Informatics (ICBI) and Department of Oncology, Georgetown University Medical Center, Washington, DC, 20007, USA.
authors.forename: Simina Maria
authors.initials: SM
authors.lastname: Boca
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois, Urbana, IL, 61801, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Mittenthal
authors.affiliation: Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois, Urbana, IL, 61801, USA. gca@illinois.edu.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Caetano-Anollés
mesh_terms: D001105:Archaea / Q000235:genetics; D005075:Biological Evolution; D019143:Evolution, Molecular; D016678:Genome / Q000235:genetics; D008958:Models, Molecular; D010802:Phylogeny; D000072417:Protein Domains / Q000235:genetics*; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics*; D020543:Proteome / Q000235:genetics*
chemical_list: D020543:Proteome
keywords: Combinatorial explosion; Domain structure; Fold family; Fold superfamily; Phylogenomic analysis; SCOP