title: Crystal structure of the bovine mitochondrial elongation factor Tu.Ts complex.
abstract: The three-dimensional structure of the bovine mitochondrial elongation factor (EF)-Tu.Ts complex (EF-Tumt.Tsmt) has been determined to 2.2-A resolution using the multi-wavelength anomalous dispersion experimental method. This complex provides the first insight into the structure of EF-Tsmt. EF-Tsmt is similar to Escherichia coli and Thermus thermophilus EF-Ts in the amino-terminal domain. However, the structure of EF-Tsmt deviates considerably in the core domain with a five-stranded beta-sheet forming a portion of subdomain N of the core. In E. coli EF-Ts, this region is composed of a three-stranded sheet. The coiled-coil domain of the E. coli EF-Ts is largely eroded in EF-Tsmt, in which it consists of a large loop packed against subdomain C of the core. The conformation of bovine EF-Tumt in complex with EF-Tsmt is distinct from its conformation in the EF-Tumt.GDP complex. When domain III of bovine EF-Tumt.GDP is superimposed on domain III of EF-Tumt in the EF-Tumt.Tsmt complex, helix B from domain I is also almost superimposed. However, the rest of domain I is rotated relative to this helix toward domain II, which itself is rotated toward domain I relative to domain III. Extensive contacts are observed between the amino-terminal domain of EF-Tsmt and domain I of EF-Tumt. Furthermore, the conserved TDFV sequence of EF-Tsmt also contacts domain I with the side chain of Asp139 contacting helix B of EF-Tumt and inserting the side chain of Phe140 between helices B and C. The structure of the EF-Tumt.Tsmt complex provides new insights into the nucleotide exchange mechanism and provides a framework for explaining much of the mutational data obtained for this complex.
authors.affiliation: Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10 C, 8000 Aarhus C, Denmark.
authors.forename: Mads Gravers
authors.initials: MG
authors.lastname: Jeppesen
authors.forename: Tomas
authors.initials: T
authors.lastname: Navratil
authors.forename: Linda Lucy
authors.initials: LL
authors.lastname: Spremulli
authors.forename: Jens
authors.initials: J
authors.lastname: Nyborg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D006147:Guanine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010444:Peptide Elongation Factor Tu / Q000737:chemistry*; D010445:Peptide Elongation Factors / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016963:Thermus thermophilus / Q000378:metabolism
chemical_list: D010445:Peptide Elongation Factors; C023512:elongation factor Ts; D006147:Guanine; D010444:Peptide Elongation Factor Tu