Crystal Structure of the Bovine Mitochondrial Elongation Factor Tu·Ts Complex

Abstract

The three-dimensional structure of the bovine mitochondrial elongation factor (EF)-Tu⅐Ts complex (EFTu mt ⅐Ts mt ) has been determined to 2.2-Å resolution using the multi-wavelength anomalous dispersion experimental method. This complex provides the first insight into the structure of EF-Ts mt . EF-Ts mt is similar to Escherichia coli and Thermus thermophilus EF-Ts in the amino-terminal domain. However, the structure of EF-Ts mt deviates considerably in the core domain with a fivestranded ␤-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-Ts mt , in which it consists of a large loop packed against subdomain C of the core. Protein biosynthesis is the process by which the ribosome translates the sequence of nucleotides in a mRNA into the sequence of amino acids in a protein. During the cyclic elongation phase, the ribosome is assisted by elongation factors (EFs) 1 (1, 2). In prokaryotes, elongation factor EF-Tu promotes the binding of aminoacyl-tRNA (aa-tRNA) to the A-site of the mRNA-programmed ribosome in the form of the ternary complex aa-tRNA⅐EF-Tu⅐GTP (3). Upon cognate interaction between the codon of mRNA and the anticodon of aa-tRNA, GTP is hydrolyzed, and EF-Tu⅐GDP is released from the ribosome. The nucleotide exchange factor, EF-Ts, binds the EF-Tu⅐GDP complex mediating the release of the GDP and forms a stable EF-Tu⅐Ts complex (1). The high concentrations of GTP in the cell help dissociate EF-Ts leaving the active EF-Tu⅐GTP complex. EF-Tu⅐GTP binds another aa-tRNA, forming a new ternary complex, and the cycle is repeated.Mitochondria contain a highly specialized protein biosynthetic machinery that is responsible for the synthesis of 13 polypeptides of the electron transport chain and the ATP synthase in the inner membrane (4). The mitochondrial translational system has a number of unique features including an altered genetic code, unusual protein-rich ribosomes, and tRNAs that lack many of the conserved residues found in canonical tRNAs (5-7). Despite these differences, mammalian mitochondria possess a translational elongation machinery with significant similarities to that of bacteria (8).Mitochondrial EF-Tu (EF-Tu mt ) is highly conserved and is 55-60% identical to bacterial EF-Tu (9). The three-dimensional structure of the EF-Tu mt ⅐GDP complex has been determined at 1.94-Å resolution (10). The overall structure is similar to that observed in the Escherichia coli and Thermus aquaticus factors, but the nucleotide-binding domain (domain I) of EF-Tu mt is in a different orientation relative to the rest of the structure compared with that observed in prokaryotic 12). Furthermore, domain III is followed by a short 11-amino acid extension that forms one helical turn. This extension seems to be specific to the mitochondrial factors and has not been observed in any of the prokaryotic factors.Bovine liver EF-Ts mt is 338 amino acids in length. The amino terminus of the mat...

Molecular-genetic characterization and rescue of a TSFM mutation causing childhood-onset ataxia and nonobstructive cardiomyopathy

“…3), that is conserved in 99 (63.9%) out of 155 animal species analyzed (GenBank, 11 September 2015; Supplementary Figure S1). The three-dimensional structure of the bovine elongation factor Tu (EFTu)-EFTs dimer (PDB 1XB2) 4 was obtained with the RasMol 2.6 program (http://www.rasmol.org). The cysteine 240 is located in EFTs subdomain C β5 strand from the core domain.…”

Methylene blue‐mediated photodynamic therapy induces mitochondria‐dependent apoptosis in HeLa Cell

“…Among them, reduction of mitochondrial elongation factor Tu, mitochondrial elongation factor Ts and electron transfer flavoprotein (Table I) were observed. Tu and Ts proteins maintain the basic mitochondrial functions, such as the synthesis of 13 polypeptides of the electron transport chain and the ATP synthase in the inner membrane [Jeppesen et al, 2005]. Electron Transfer Flavoprotein is responsible for electron shuttles between primary flavoprotein dehydrogenases involved in mitochondrial fatty acid and amino acid catabolism and the membrane-bound electron transfer flavoprotein ubiquinone oxidoreductase [Roberts et al, 1996].…”

Coordination of Eukaryotic Translation Elongation Factor 1A (eEF1A) Function in Actin Organization and Translation Elongation by the Guanine Nucleotide Exchange Factor eEF1Bα

“…Thus, eEF1B␣ can alter the distribution of eEF1A between translational and non-canonical functions. Evolutionarily, this is particularly important because despite the high degree of sequence and structural conservation between eEF1A, EF-Tu, and EF-Tu mt ; there is a major difference in how these proteins form a complex with their GEFs (8,10,11). To achieve guanine nucleotide exchange catalysis, all three GEFs bind to domain I as this region consists of the conserved G-domains and Mg 2ϩ binding site (Fig.…”

“…The co-crystal structures of eEF1A:eEF1B␣ C terminus:GDP: Mg 2ϩ and eEF1A:eEF1B␣ C terminus:GDPNP (8, 9) demonstrated a surprising structural divergence from the bacterial EF-Tu-EF-Ts (10) and mammalian mitochondrial EF-Tu mt -EF-Ts mt (11). While the G-proteins have a similar topology and consist of three well-defined domains, a striking difference was observed in binding sites for their GEFs.…”