This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Evolutionary changes in a key protein synthesis enzyme, isoleucyl-tRNA synthetase (IleRS), may help bacteria fine-tune how quickly proteins are made, report researchers from Institute of Science Tokyo, Japan; the University of Zagreb Faculty of Science, Croatia; and ETH Zürich, Switzerland. Researchers traced the enzyme's evolutionary history and identified three distinct IleRS clades.
Their findings show that C-terminal remodeling, including repeated loss of a structural region called "INS," may have helped refine enzyme activity and reaction speed. The study is published in the journal Nature Communications. Every cell contains the millions of protein molecules necessary for various cellular functions.
Protein synthesis is the process through which the information encoded in our DNA is converted into the proteins needed for sustaining life. During this process, transfer RNAs (tRNAs) act as molecular carriers, bringing specific amino acids to the ribosome, where they are assembled into proteins according to the genetic information encoded in messenger RNA (mRNA), which is derived from DNA. Before a tRNA can perform this role, it must be "charged" with the correct amino acid.
This crucial step is carried out by a family of enzymes called aminoacyl-tRNA synthetases (AARSs), which recognize specific tRNAs and then attach the corresponding amino acid to the tRNA (aminoacylation). The accuracy of this process is essential because attaching the wrong amino acid can lead to errors in the synthesized protein. One member of this family is isoleucyl-tRNA synthetase (IleRS), which pairs the amino acid isoleucine with its corresponding tRNA.
IleRS has traditionally been classified into two forms, IleRS1 and IleRS2, based on differences in their C-terminal regions. However, the evolutionary history and functional significance of these differences have remained unclear. Now, a study led by Professors Liam M.
Longo from the Earth-Life Science Institute, Institute of Science Tokyo, Japan; Ita Gruic-Sovulj from the Department of Chemistry, University of Zagreb Faculty of Science, Croatia; and Nenad Ban from ETH Zürich, Switzerland, reveals a more complex picture of how this essential enzyme has evolved. The study combines bioinformatics, X-ray crystallography and extensive kinetic characterization, reconstructing the evolutionary history of IleRS and investigating how evolutionary changes in the enzyme affect tRNA recognition, enzyme function and aminoacylation rate. "Our findings suggest that bacteria have repeatedly streamlined parts of this enzyme, potentially enhancing aminoacylation rate and contributing to faster protein synthesis," notes Longo.
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