The View From Here – by Charles Yanofsky

We have invited a number of distinguished microbiologists to share some of their thoughts with us.
 

The Evolution of the Genetic Code

Zabriskie Point. Source

Although the genetic code is well established, a very ex­citing unsolved problem is discovering how codons were related to amino acids in the evolution of protein synthe­sis. How did a tRNA and a tRNA synthetase first evolve, and what was their ancestral source? How were the genes for the first tRNA and tRNA synthetase duplicated and how was their specificity varied? Can we offer any explanation for why there are two classes of tRNA syn­thetases? Can one predict which tRNAs evolved from one another? Similarly, can we predict which tRNA syntheta­ses evolved from an existing tRNA synthetase?
 

A related series of exciting experiments would be to attempt to reproduce some evolutionary events and determine how many mutational changes it would take – and where – to evolve a tRNA synthetase with new specificity from an existing synthetase. Suppression studies many years ago showed that tRNAs may acquire new decoding specificity following single mutational changes, but synthetase suppressors were not recovered, as I recall. Also, we now know that synthetases recognize both the anticodon and acceptor end sequence of each tRNA – is this consistent with what is known about suppressing tRNAs?
 

Reference
Carter CW Jr. (2008). Whence the genetic code? Thawing the 'Frozen Accident'. Heredity 100, 339–340

 

Charles Yanofsky is Professor Emeritus of Biological Sciences at Stanford University and a 2003 recipient of the National Medal of Science.

 
 

 
 

Comments

[Mark O. Martin]

What a fantastic new feature, Elio and Merry. Charley Yanofsky is one of the smartest people I met in graduate school (along with Allan Campbell, Phil Hanawalt, and my thesis advisor Sharon Long).

When these folks muse about a topic, all microbiologists should listen very carefully indeed. I sure do.

Thanks for this feature, Elio and Merry!