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Báo cáo khoa học: Functional effects of deleting the coiled-coil motif in Escherichia coli elongation factor Ts

Elongation factor Ts (EF-Ts) is the guanine nucleotide-exchange factor for elongation factor Tu (EF-Tu) that is responsible for promoting the binding of aminoacyl-tRNA to the mRNA-programmed ribosome.The struc-ture of the Escherichia coliEF-Tu–EF-Ts complex reveals a protruding antiparallel coiled-coil motif in EF-Ts, which is responsible for the dimerization of EF-Ts in the crystal. In this study, the sequence encoding the coiled-coil motif in EF-Ts was deleted from the genome in Escherichia coli by gene replacement | Eur. J. Biochem. 270 4294-4305 2003 FEBS 2003 doi 10.1046 j.1432-1033.2003.03822.x Functional effects of deleting the coiled-coil motif in Escherichia coli elongation factor Ts Henrik Karring1 Asgeir Bjornsson2 Soren Thirup1 Brian F. C. Clark1 and Charlotte R. Knudsen1 1 Department of Molecular Biology Aarhus University Denmark 2deCODE Genetics Inc. Reykjavik Iceland Elongation factor Ts EF-Ts is the guanine nucleotide-exchange factor for elongation factor Tu EF-Tu that is responsible for promoting the binding of aminoacyl-tRNA to the mRNA-programmed ribosome. The tluuc-ture of the Escherichia coli EF-Tu-EF-Ts complex reveals a protruding antiparallel coiled-coil motif in EF-Ts which is responsible for the dimerization of EF-Ts in the crystal. In this study the sequence encoding the coiled-coil motif in EF-Ts was deleted from the genome in Escherichia coli by gene replacement. Tile rgwwth 1 ale of die reuuinrig mutant strain was 70-95 of that of the wild-type strain depending on the growth conditions used. Tte mutant strain sensed amino acid starvation and synthesized the nucleotides guanosine 5 -diphosphate 3 -diphosphate and guanosine 5 -triphosphate 3 -diphosphate at a lower cell density than the wild-type strain. Detetinn of file coiled-coil motif only partially reduced the ability of EF-Ts to stimulate the guanine nucleotide exchange in EF-Tu. Howvver. die conhnntration ơi suanine uc t e--tides GDP and GTP required to dissociate the mutant EF-Tu-EF-Ts complex was at least two orders of magnitude lower than that for the wild-type complex.The results show that the coiled-coil motif plays a significant role in the ability of EF-Ts to compete with guanine nucleotides for the binding to EF-Tu. The avdvatt eesLnSs also indicate that the deletion alters the competition between EF-Ts and kirromycin for the binding to EF-Tu. Keywords elongation factor Ts elongation factor Tu guanine nucleotide exchange kirromycin p ppGpp. Elongation factor Tu EF-Tu and elongation .