title: Structural outline of the detailed mechanism for elongation factor Ts-mediated guanine nucleotide exchange on elongation factor Tu.
abstract: Translation elongation factor EF-Tu belongs to the superfamily of guanine-nucleotide binding proteins, which play key cellular roles as regulatory switches. All G-proteins require activation via exchange of GDP for GTP to carry out their respective tasks. Often, guanine-nucleotide exchange factors are essential to this process. During translation, EF-Tu:GTP transports aminoacylated tRNA to the ribosome. GTP is hydrolyzed during this process, and subsequent reactivation of EF-Tu is catalyzed by EF-Ts. The reaction path of guanine-nucleotide exchange is structurally poorly defined for EF-Tu and EF-Ts. We have determined the crystal structures of the following reaction intermediates: two structures of EF-Tu:GDP:EF-Ts (2.2 and 1.8Å resolution), EF-Tu:PO4:EF-Ts (1.9Å resolution), EF-Tu:GDPNP:EF-Ts (2.2Å resolution) and EF-Tu:GDPNP:pulvomycin:Mg(2+):EF-Ts (3.5Å resolution). These structures provide snapshots throughout the entire exchange reaction and suggest a mechanism for the release of EF-Tu in its GTP conformation. An inferred sequence of events during the exchange reaction is presented.
authors.affiliation: Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark. Electronic address: sth@mbg.au.dk.
authors.forename: Søren S
authors.initials: SS
authors.lastname: Thirup
authors.affiliation: Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark.
authors.forename: Lan Bich
authors.initials: LB
authors.lastname: Van
authors.affiliation: Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark.
authors.forename: Tine K
authors.initials: TK
authors.lastname: Nielsen
authors.affiliation: Aarhus University, Department of Molecular Biology and Genetics, Center for Structural Biology, DK-8000 Aarhus C, Denmark.
authors.forename: Charlotte R
authors.initials: CR
authors.lastname: Knudsen
mesh_terms: D006150:Guanine Nucleotides / Q000737:chemistry* / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D006150:Guanine Nucleotides; D010445:Peptide Elongation Factors; C023512:elongation factor Ts; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D010444:Peptide Elongation Factor Tu
keywords: Crystal structure; Elongation factor Ts; Elongation factor Tu; Guanine nucleotide exchange; G–GEF complex