Functional effects of deleting the coiled-coil motif in Escherichia coli elongation factor Ts

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Abstract

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 structure 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. The growth rate of the resulting mutant strain was 70-95% of that of the wild-type strain, depending on the growth conditions used. The 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. Deletion of the coiled-coil motif only partially reduced the ability of EF-Ts to stimulate the guanine nucleotide exchange in EF-Tu. However, the concentration of guanine nucleotides (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 present results also indicate that the deletion alters the competition between EF-Ts and kirromycin for the binding to EF-Tu.

Detaljer

Författare
  • Henrik Karring
  • Asgeir Björnsson
  • Soren Thirup
  • Brian F C Clark
  • Charlotte R Knudsen
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Reumatologi och inflammation
Originalspråkengelska
Sidor (från-till)4294-4305
TidskriftEuropean Journal of Biochemistry
Volym270
Utgåva nummer21
StatusPublished - 2003
PublikationskategoriForskning
Peer review utfördJa