Day 073 - Evolutionary search

Submitted by Sam on 2 August, 2011 - 00:10

The complexity of synthesizing proteins for specific purposes is so great that predicting the amino acid sequences necessary to generate desired behaviour is a huge challenge. Mutations far away from the protein’s active site can influence its function, and the smallest of changes in the structure of an enzyme can have a large impact on its catalytic efficacy – a key concern for engineers creating proteins for industrial applications. Even for a small protein of only 100 amino acids long there are more possible sequences than there are atoms in the universe.

What this means is that an exhaustive search through the space of all possible proteins for the fittest protein for a particular purpose is essentially unachievable, just as a complete search through all possible chess games to decide the absolutely optimal next move is computationally impractical. This is true both for scientists and for nature. This means that even though evolution has been searching the space of all possible proteins for billions of years for solutions to survival, it has in fact explored only a minute corner of all possible variations. All evolved solutions are likely to be 'good enough' rather than the absolute optimum – it just so happens that the ones already 'discovered' are sufficient to create and maintain the diversity and richness of life on planet earth.

New ways of efficiently searching this vast space of possible sequences will reveal proteins with properties that have never before existed in the natural world, and which will hopefully provide answers to many of our most pressing problems. Directed evolution not only provides a faster way of searching this space than many other methods, but it also leaves a complete 'fossil record' of the evolutionary changes that went into evolving a specific protein, providing data on the intermediate stages which will offer insight after detailed study into the relationship between protein sequence and function. Unlike natural evolution, directed evolution can also explore sequences which aren't directly biologically relevant to a single organism's survival, providing a library of industrially relevant proteins, and perhaps one day creating bacteria capable of answering worldwide problems caused by pollution and fossil fuel shortage.

Attribution Noncommercial Share Alike
This text, Day 073 - Evolutionary search, by Sam Haskell is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike license.
Drupal theme by Kiwi Themes.