National Center for
4PC3: Elongation factor Tu:Ts complex with partially bound GDP
Structural outline of the detailed mechanism for elongation factor Ts-mediated guanine nucleotide exchange on elongation factor Tu
J. Struct. Biol. (2015) 191 p.10-21
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 1.8A resolution), EF-Tu:PO4:EF-Ts (1.9A resolution), EF-Tu:GDPNP:EF-Ts (2.2A resolution) and EF-Tu:GDPNP:pulvomycin:Mg(2+):EF-Ts (3.5A 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.