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

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.

Phenylmethanesulfonyl fluoride inactivates an archaeal superoxide dismutase by chemical modification of a specific tyrosine residue. Cloning, sequencing and expression of the gene coding for Sulfolobus solfataricus superoxide dismutase

The gene encoding the superoxide dismutase from the hyperthermophilic archaeon Sulfolobus solfataricus (SsSOD) was cloned and sequenced and its expression in Escherichia coli obtained. The chemicophysical properties of the recombinant SsSOD were identical with those of the native enzyme. The recombinant SsSOD possessed a covalent modification of Tyr41, already observed in native SsSOD [Ursby, T., Adinolfi, B.S., Al-Karadaghi, S., De Vendittis, E. & Bocchini, V. (1999) J. Mol. Biol. 286, 189--205]. HPLC analysis of SsSOD samples prepared from cells treated or not with phenylmethanesulfonyl fluoride (PhCH(2)SO(2)F), a protease inhibitor routinely added during the preparation of cell-free extracts, showed that the modification was caused by PhCH(2)SO(2)F. Refinement of the crystal model of SsSOD confirmed that a phenylmethanesulfonyl moiety was attached to the hydroxy group of Tyr41. PhCH(2)SO(2)F behaved as an irreversible inactivator of SsSOD; in fact, the specific activity of both native and recombinant enzyme decreased as the percentage of modification increased. The covalent modification caused by PhCH2SO2F reinforced the heat stability of SsSOD. These results show that Tyr41 plays an important role in the enzyme activity and the maintenance of the structural architecture of SsSOD.

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.