The first nucleotide sequence of an archaeal elongation factor 1 beta gene

Crystallization and preliminary X-ray crystallographic analysis of the Sulfolobus solfataricus nucleotide-exchange factor 1beta

The nucleotide-exchange factor isolated from the hyperthermophilic archaeon Sulfolobus solfataricus (SsEF-1beta) consists of 90 residues and differs from eukaryal EF-1betas. The protein has been successfully crystallized using either microbatch-under-oil or vapour-diffusion methods. Crystals of native SsEF-1beta diffract to 1.97 A resolution and belong to space group P2(1)2(1)2, with unit-cell parameters a = 106.46, b = 54.87, c = 44.03 A. Diffraction data have also been collected from a selenomethionine derivative of SsEF-1beta at 1.83 A resolution. Model building using the phases derived from the MAD experiment is in progress.

The interaction between the archaeal elongation factor 1alpha and its nucleotide exchange factor 1beta

In Sulfolobus solfataricus the binding of the exchange factor 1beta (SsEF-1beta) to SsEF-1alpha-GDP displaces the nucleotide and the SsEF-1alpha-SsEF-1beta complex is formed. The complex itself is stable, but it dissociates upon the addition of GDP or Gpp(NH)p but not ATP. Since the rate of the formation of the SsEF-1alpha-SsEF-1beta complex is significatively slower than the rate of the nucleotide exchange catalyzed by SsEF-1beta it can be inferred that in vivo the GDP/GTP exchange reaction proceeds via an SsEF-1alpha-SsEF-1beta interaction without involving the formation of a stable binary complex as an intermediate.

Protein engineering on enzymes of the peptide elongation cycle in Sulfolobus solfataricus

The present article is a review of the work done on the elongation factors EF-1 alpha, EF-2 and EF-1 beta isolated from the hyperthermophilic archaeon Sulfolobus solfataricus. The molecular, physical and biochemical properties of the intact, truncated, mutant or chimeric forms are described and compared.

Expression in Escherichia coli of the elongation factor 1beta gene and its nucleotide T160C mutant from the archaeon Sulfolobus solfataricus

The guanine nucleotide exchange factor EF-1beta gene from the thermoacidophilic archaeon Sulfolobus solfataricus (SsEF-1beta) was amplified by PCR and cloned into the pT7-7 expression vector. One of four selected clones harbored the T160C nucleotide substitution leading to the Y54H amino acid change in a hydrophobic region of SsEF-1beta, caused by a nucleotide misincorporation of the Taq DNA polymerase during PCR. The resulting plasmids were used to transform the Escherichia coli BL21(DE3)pLysE strain. Upon induction with isopropyl beta-d-thiogalactopyranoside about 1.4 mg of the recombinant SsEF-1beta (recSsEF-1beta) and Y54HSsEF-1beta were obtained from 1 liter of cell culture. recSsEF-1beta and Y54HSsEF-1beta were both able to catalyze the GDP/GTP exchange on SsEF-1alpha as observed with the wild-type SsEF-1beta. In addition, the heat inactivation profiles of recSsEF-1beta and Y54HSsEF-1beta were identical, being both half inactivated after 30 min treatment at 105 degrees C. These results suggest that Tyr 54 is not essential for the nucleotide exchange activity and is not involved in the thermostability of SsEF-1beta.

Archaeal elongation factor 1 beta is a dimer. Primary structure, molecular and biochemical properties

The elongation factor 1 beta (EF-1 beta), that in eukarya and archaea promotes the replacement of GDP by GTP on the elongation factor 1 alpha x GDP complex, was purified to homogeneity from the thermoacidophilic archaeon Sulfolobus solfataricus (SsEF-1 beta). Its primary structure was established by sequenced Edman degradation of the entire protein or its proteolytic peptides. The molecular weight of SsEF-1 beta was estimated as about 10000 or 20000 under denaturing or native conditions respectively; this finding suggests that the native protein exists as a dimer. The peptide chain of SsEF-1 beta is much shorter than that of its eukaryotic analogues and homology is found only at their C-terminal region; no homology exists between SsEF-1 beta and eubacterial EF-Ts. At 50 degrees C, at a concentration of SsEF-1 beta 5-fold higher than that of SsEF-1 alpha x [3H]GDP the rate of the exchange of [3H]GDP for GTP becomes about 160-fold faster. An analysis of the values of the energetic parameters indicates that in the presence of SsEF-1 beta the GDP/GTP exchange is entropically favoured. At 100 degrees C the half-life of SsEF-1 beta is about 4 h.

Elongation factor Ts from Thermus thermophilus-- overproduction in Escherichia coli, quaternary structure and interaction with elongation factor Tu

The gene encoding the elongation factor Ts from Thermus thermophilus was sequenced, cloned and the protein overproduced in Escherichia coli. In comparison to the EF-Ts from E. coli with 282 amino acid residues, EF-Ts from T. thermophilus is considerably shorter, differing by 86 amino acids. EF-Ts from the thermophile is stable at high temperatures, which facilitates its separation from E. coli proteins. Purified T. thermophilus EF-Ts forms a homodimer with a disulfide bridge between the two cysteine residues at position 190. The modification of Cys19O by iodoacetamide affects neither the dimerization nor the ability of EF-Ts to facilitate the nucleotide exchange of elongation factor Tu. The disulfide bridge was detected only in purified EF-TS, but not in protein extracts immediately after cell disruption. The physiological role of this disulfide bridge remains, therefore, unclear. Besides the quaternary (EF-TU . EF-Ts)2 complex, a ternary EF-TU . EF-Ts2 complex was detected by gel permeation chromatography and polyacrylamide gel electrophoresis. Trypsin cleavage after Lys48 or modification of Cys78 yield inactive EF-Ts, that does not bind to EF-Tu but is still capable of forming homodimers.