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Immutable No More: Evolved Ribosomes Expand the Chemical Repertoire of Living Cells
How a molecular machine four billion years in the making was modified to imbue cells with unnatural abilities.
Four billion years ago, a single-celled organism floated in the primordial soups of early earth. This ancient organism already had many of the makings of modern life forms, including a functional ribosome, the dynamic, nanoscopic machine that makes the thousands of unique proteins that cells need to survive.
The ribosome reads an mRNA message that direct the positions of specific building blocks in the final protein polymer, a process known as translation. Two separate ribosomal subunits, the large and the small, come together to decode these messages. The catalytic activity of the ribosome is derived from ribosomal RNA sequences residing in each of the subunits — in the large subunit, a strand of RNA catalyzes the peptide bonds between amino acids, while the small subunit contains an RNA that decodes the precise position in the mRNA message to begin translation. The process of translation is such a delicate dance that it has remained relatively unaltered for nearly four billion years and took scientists several decades to decipher. Solving the structure of the ribosome and its milieu of interactions with other cellular components earned Venki Ramakrishnan, Thomas…
