1tfe: Difference between revisions

[[Image:1tfe.gif|left|200px]]<br /><applet load="1tfe" size="350" color="white" frame="true" align="right" spinBox="true"  

Elongation factor Ts (EF-Ts) functions as a nucleotide-exchange factor by binding elongation factor Tu (EF-Tu) and accelerating the GDP dissociation from EF-Tu; thus EF-Ts promotes the transition of EF-Tu from the inactive GDP form to the active GTP form. Thermus thermophilus EF-Ts exists as a stable dimer in solution which binds two molecules of EF-Tu to form a (EF-Tu.EF-Ts)2 heterotetramer. Here we report the crystal structure of the dimerization domain of EF-Ts from T. thermophilus refined to 1.7 A resolution. A three-stranded antiparallel beta-sheet from each subunit interacts to form a beta-sandwich that serves as an extensive dimer interface tethered by a disulfide bond. This interface is distinctly different from the predominantly alpha-helical one that stabilizes the EF-Ts dimer from Escherichia coli [Kawashima, T., et al. (1996) Nature 379, 511-518]. To test whether the homodimeric form of T. thermophilus EF-Ts is necessary for catalyzing nucleotide exchange, the present structure was used to design mutational changes within the dimer interface that disrupt the T. thermophilus EF-Ts dimer but not the tertiary structure of the subunits. Surprisingly, EF-Ts monomers created in this manner failed to catalyze nucleotide exchange in EF-Tu, indicating that, in vitro. T. thermophilus EF-Ts functions only as a homodimer.

1TFE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TFE OCA].  

[[Category: Sigler, P B.]]

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