title: Archaeal cold-adapted proteins: structural and evolutionary analysis of the elongation factor 2 proteins from psychrophilic, mesophilic and thermophilic methanogens.
abstract: To identify structural features important for low temperature activity in archaeal proteins, elongation factor 2 (EF-2) genes (aef2) were sequenced from psychrophilic, mesophilic and thermophilic methanogens. Scatter plots were used to compare evolutionary distances for EF-2 amino acid sequences vs. 16S-rRNA sequences from methanogens growing at diverse temperatures. The absence of a temperature bias for the rate of protein vs. nucleic acid evolution demonstrated the importance of comparing closely related proteins in order to identify changes indicative of thermal adaptation. Three-dimensional modelling of the new EF-2 sequences enabled the identification of amino acid residues that may be important for conferring low temperature activity and included greater structural flexibility produced by fewer salt bridges, less packed hydrophobic cores and the reduction of proline residues in loop structures.
authors.affiliation: School of Microbiology and Immunology, University of New South Wales, Sydney, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Thomas
authors.forename: R
authors.initials: R
authors.lastname: Cavicchioli
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics*; D002455:Cell Division; D019605:Euryarchaeota / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D011487:Protein Conformation; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D012336:RNA, Ribosomal, 16S