Crystal structure of active elongation factor Tu reveals major domain rearrangements

Abstract

The crystal structure of intact elongation factor Tu (EF-Tu) from Thermus thermophilus has been determined and refined at an effective resolution of 1.7 A, with incorporation of data extending to 1.45 A. The effector region, including interaction sites for the ribosome and for transfer RNA, is well defined. Molecular mechanisms are proposed for transduction and amplification of the signal induced by GTP binding as well as for the intrinsic and effector-enhanced GTPase activity of EF-Tu. Comparison of the structure with that of EF-Tu-GDP reveals major mutual rearrangements of the three domains of the molecule.

Functional Interactions between the G′ Subdomain of Bacterial Translation Factor EF-G and Ribosomal Protein L7/L12

“…Early research identified L7/L12, 4 a protein component of one of the peripheral stalks of the ribosome, as an important contributor to GTPase activation of both factors (7,8). More recent studies identified residues of the C-terminal domain (CTD) of L7/L12, important for GTPase activation and rapid association of both factors with the ribosome (9,10).…”

“…The hydrolysis reaction involves in-line nucleophilic attack of a water molecule on the ␥-phosphorus of GTP (2). On EF-Tu (and possibly also EF-G), this reaction is catalyzed by a conserved histidine residue (3), whose side chain is believed to rotate to a position next to the water molecule (4). In contrast to EF-Tu, EF-G contains a GЈ subdomain, which is invariably inserted between ␣-helices D G and E G (5).…”

The pathway to GTPase activation of elongation factor SelB on the ribosome

“…These include the universal elongation factor EF-Tu (in bacteria, or eEF1A in eukaryotes) and a specialized factor SelB 1 (eEFSec-SBP2 in eukaryotes 2 ). EF-Tu and SelB deliver aminoacyl-tRNA (aa-tRNA) to the ribosome at the cost of GTP hydrolysis 3,4 . In contrast to EF-Tu, which is a carrier for all canonical aa-tRNAs, SelB is specialized to bind only the tRNA that is specific for Sec 5,6 .…”

Mutants of EF‐Tu defective in binding aminoacyl‐tRNA

“…Thus, substitutions in the domain interface, many of which apparently decrease the affinity of aa-tRNA for EFTu, are in some cases also associated with alterations in the interaction between EF-Tu and the bound guanine nucleotide. Current structural information [1,2,31] does not indicate any direct interaction between these residues and the guanine nucleotide, suggesting that these effects are indirect.…”

“…Elongation factor Tu (EF-Tu) is a protein of 393 amino acids folded into three distinct structural domains [1,2] and forms a ternary complex with GTP and aa-tRNA. The ternary complex participates in protein biosynthesis by mediating the interaction of aa-tRNA with the ribosomal A site, accelerating very significantly the rate of aa-tRNA binding to the ribosome, and reducing missense errors by more than 2 orders of magnitude.…”