The reactions of the sulfhydryl groups on the elongation factors Tu and Ts

Section: Discussionmentioning

confidence: 99%

Studies on Polypeptide‐Chain‐Elongation Factors from an Extreme Thermophile, Thermus thermophilus HB8

Nakamura¹,

Ohta²,

Arai³

et al. 1978

“…In the reaction with [14C]MalNEt, there is a marked temperature effect in the reactivity of the two sulphydryls, which could be the basis of a specific modification reaction at 0 "C. Whether the two sulphydryl groups of EF-Tu (BS) correspond to SH1 and SH2 of EF-Tu (EC) is yet to be determined, although it appears that one of the two, the slower reacting -SH group, is near the GDP-binding site, since it is partially protected against reaction by GDP. EF-Ts (EC) has two sulphydryl groups, one of which is reactive and essential for its catalytic activity [24,25]. Our results show that EF-Tu (BS) contains three sulphydryl groups all of which are reactive in the native and denatured protein although two of these react much slower than the third in the reaction with Nbs,.…”

Section: The Reaction Of [14c]malnet With Ef-tumentioning

confidence: 92%

“…Miller et al [24] and Arai et al [25] have shown that there are three sulphydryl groups in EF-Tu (EC), two of which react under non-denaturing conditions. Of these, one designated SH1, is protected against reaction with p-mercuribenzoate, Nbs, and MalNEt by the nucleotides GDP and GTP, while another, SH2, reacts under these conditions.…”

Section: The Reaction Of [14c]malnet With Ef-tumentioning

confidence: 99%

Elongation Factor T from Bacillus stearothermophilus and Escherichia coli

Wittinghofer¹,

Leberman²

1976

Homogeneous preparations of elongation factors EF‐Tu and EF‐Ts from Bacillus stearothermophilus have been obtained with specific activities of 20000 ± 2000 and 500000 ± 50 000 units/ mg, respectively. By dodecylsulphate‐polyacrylamide gel electrophoresis the molecular weight of EF‐Tu was found to be 49000 ± 2000 and of EF‐Ts 35500 ± 1000. Nucleotide‐free EF‐Tu was prepared by using ITP as a GDP‐binding‐site‐directed analogue. EF‐Tu was shown to contain two sulphydryl groups, one reacting fast and one slowly with N‐ethylmaleimide and 5,5′‐dithio‐bis(2nitrobenzoic acid) under non‐denaturing conditions. The same reagents were shown to react with the three sulphydryl groups of EF‐Ts in the native state. The heat stabilities of EF‐Tu and EF‐Ts are reversed with respect to the Escherichia coli factors, EF‐Tu being the more stable protein; even nucleotide‐free EF‐Tu is relatively stable with a half‐life at room temperature of about 35 h.

“…The protein which did not adsorb to the column contained the bulk of the EF-P activity. Trace amounts of active EF-Ts and EF-G were inactivated by incubation of EF-P with 10 mM N-ethylmaleimide for 5 min at O*C [15,16], followed by addition of excess dithiothreitol.…”

Section: Methodsmentioning

confidence: 99%

Peptide Bond Formation Stimulated by Protein Synthesis Factor EF‐P Depends on the Aminoacyl Moiety of the Acceptor

Glick

Chládek²,

Ganoza

1979

Elongation factor EF‐P is a soluble protein that stimulates peptide bond synthesis catalyzed by the 50‐S ribosomal subunit. This factor was previously identified and characterized based on its ability to promote the synthesis of formylmethionine‐puromycin. In the present work, we tested the ability of EF‐P to promote peptide bond synthesis between ribosome‐bound fMet‐tRNA and several analogues of the 3′ terminus of aminoacyl‐tRNA, i.e. the cytidylyl(3′‐5′)‐[2′(3′)‐O‐l‐aminoacyladenosines]. EF‐P promoted synthesis to the greatest extent with certain acceptors which were otherwise inefficient in the peptidyl transferase reaction. This activity of EF‐P could not be replaced by the other soluble proteins known to be involved in polypeptide synthesis, such as EF‐Tu, EF‐Ts and EF‐G. One role of EF‐P in protein synthesis may be to allow peptide bond synthesis to occur more efficiently with some aminoacyl‐tRNAs that are poor acceptors for the ribosomal peptidyl transferase.