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13:19
Chemical Triphosphorylation of Oligonucleotides
Published on: June 2, 2022
Two enzymes bound to one transfer RNA assume alternative conformations for consecutive reactions
Takuhiro Ito1, Shigeyuki Yokoyama
1Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Nature
|October 1, 2010
Summary
Researchers elucidated the bacterial glutamine transamidosome structure, revealing how glutamyl-tRNA synthetase (GluRS) and GatCAB cooperate to synthesize Gln-tRNA(Gln) efficiently.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- In bacteria and archaea, glutamyl-tRNA synthetase (GluRS) modifies tRNA(Glu) and tRNA(Gln), with amidotransferase converting Glu-tRNA(Gln) to Gln-tRNA(Gln).
- The precise mechanisms of tRNA recognition and enzyme cooperation in Gln-tRNA(Gln) synthesis are not fully understood.
Purpose of the Study:
- To determine the structure and mechanism of the glutamine transamidosome, a complex involved in Gln-tRNA(Gln) synthesis.
- To elucidate how GluRS and GatCAB recognize their tRNA substrates and coordinate their activities.
Main Methods:
- Formation and purification of the glutamine transamidosome from Thermotoga maritima.
- Determination of the complex's crystal structure at 3.35 Å resolution.
Main Results:
- The crystal structure revealed how GluRS recognizes common tRNA features and GatCAB specifically recognizes tRNA(Gln).
- GluRS adopts a productive form binding tRNA(Gln)'s acceptor arm, while GatCAB remains non-productive, awaiting Glu-tRNA(Gln) formation.
- Enzyme catalytic bodies compete for tRNA(Gln), necessitating sequential activation and an intermediate non-productive state for efficient Gln-tRNA(Gln) synthesis.
Conclusions:
- The glutamine transamidosome structure provides insights into the coordinated action of GluRS and GatCAB for efficient Gln-tRNA(Gln) synthesis.
- The identified hinges allow conformational flexibility, enabling the enzymes to switch between productive and non-productive states.
- This mechanism ensures efficient synthesis of Gln-tRNA(Gln) while minimizing the release of unstable intermediates.
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