title: Bacterial protein structures reveal phylum dependent divergence.
abstract: Protein sequence space is vast compared to protein fold space. This raises important questions about how structures adapt to evolutionary changes in protein sequences. A growing trend is to regard protein fold space as a continuum rather than a series of discrete structures. From this perspective, homologous protein structures within the same functional classification should reveal a constant rate of structural drift relative to sequence changes. The clusters of orthologous groups (COG) classification system was used to annotate homologous bacterial protein structures in the Protein Data Bank (PDB). The structures and sequences of proteins within each COG were compared against each other to establish their relatedness. As expected, the analysis demonstrates a sharp structural divergence between the bacterial phyla Firmicutes and Proteobacteria. Additionally, each COG had a distinct sequence/structure relationship, indicating that different evolutionary pressures affect the degree of structural divergence. However, our analysis also shows the relative drift rate between sequence identity and structure divergence remains constant.
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, 68588-0304, United States.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Shortridge
authors.forename: Thomas
authors.initials: T
authors.lastname: Triplet
authors.forename: Peter
authors.initials: P
authors.lastname: Revesz
authors.forename: Mark A
authors.initials: MA
authors.lastname: Griep
authors.forename: Robert
authors.initials: R
authors.lastname: Powers
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000145:classification*; D001426:Bacterial Proteins / Q000737:chemistry*; D019143:Evolution, Molecular; D008958:Models, Molecular; D010802:Phylogeny; D017510:Protein Folding
chemical_list: D001426:Bacterial Proteins