New method called native chemical ligation provides insight into ribosome function

Their study, published on October 31 in the journal natural chemistryused a novel method of stable peptide binding to transfer RNAs.

Inside tiny cellular machines called ribosomes, strings of genetic material called messenger RNAs (mRNAs) combine with corresponding transfer RNAs (tRNAs) to create sequences of amino acids that exit the ribosome as proteins. Unfinished proteins called “nascent chains” are left attached to the ribosome.

Certain nascent chains were previously known to regulate ribosome activity and sometimes interfere with antibiotics, many of which work by targeting bacterial ribosome activity. However, the mechanism was unknown, due to the difficulty in visualizing ribosome-peptide-drug interactions with nascent chains still attached to the ribosome.

The researchers used a method called native chemical ligation in which adding the amino acid cysteine ​​to tRNA allowed the tRNA to fuse with a custom peptide to give “peptidyl-tRNA”. The resulting high-resolution ribosomal structure and captured electron density maps for peptidyl-tRNA of different lengths inside the ribosome were obtained by X-ray crystallography. Analysis of these structures provides new insights into the mechanism of the catalytic center of the ribosome.

“This method opens countless avenues for structural and functional studies aimed at understanding the mechanisms of ribosome function, as well as sequence-specific ribosome blockade induced by certain antibiotics,” said co-author Yury Polikanov, PhD. , associate professor of biology at the UIC. A declaration.

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