Related Experiment Videos
Variant of human enzyme sequesters reactive intermediate
Karla L Ewalt1, Xiang-Lei Yang, Francella J Otero
1Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, Mail Drop BCC-379, La Jolla, California 92037, USA. kewalt@scripps.edu
Biochemistry
|March 16, 2005
Summary
A human tryptophanyl-tRNA synthetase variant sequesters tryptophanyl adenylate, hindering pyrophosphate (PPi) hydrolysis. This structural change ensures efficient aminoacylation by preventing wasteful ATP resynthesis.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Enzyme-catalyzed reactions in cells often utilize coupled hydrolytic reactions for efficient product formation.
- Protein synthesis involves aminoacyl-tRNA synthetases forming aminoacyl-adenylates, which then react with tRNA.
Purpose of the Study:
- To investigate a polymorphic variant of human tryptophanyl-tRNA synthetase.
- To understand the mechanism by which this variant affects enzyme activity and product formation.
Main Methods:
- Structural analysis of the tryptophanyl-tRNA synthetase variant.
- Biochemical assays to assess enzyme activity and substrate binding.
Main Results:
- The variant enzyme sequesters tryptophanyl adenylate, preventing its reaction with pyrophosphate (PPi).
- Structural changes reorient residues critical for ATP phosphate and PPi binding.
- The reorientation does not impede the reaction with tRNA, maintaining efficient aminoacylation.
Conclusions:
- The studied variant of human tryptophanyl-tRNA synthetase exhibits altered substrate binding and reaction kinetics.
- This specific structural modification enhances protein synthesis efficiency by preventing wasteful side reactions.