How to direct evolution
In David Ackerley’s lab at Victoria University in Wellington, they are using directed evolution to make enzymes with new functions. Here, find out the steps involved in evolving an enzyme.
Step 1: Designing PCR primers
Step 2: Making gene variants
Then you use a ‘sloppy’ or error-prone version of PCR to introduce mutations into the bacterial gene. This step will give you millions of random gene variants.
Introducing mutations into a gene speeds up the evolutionary process.
Step 3: From gene to mRNA to enzyme
You need to translate the genes into proteins.
You can insert the genes into a bacterial plasmid and then introduce them into bacterial cells. The genes are translated into enzymes inside the bacterial cells.
The variations in these genes may cause changes in the amino acid sequence of the enzyme. Any changes in the amino acid sequence of the enzyme can affect its structure and function.
Step 4: Detecting improved enzymes
You need to test whether the enzyme’s function is changed. A lot of gene variants are produced, so you need a test that is simple and easy to do. This is called a screening test.
The screening test allows you to detect enzymes that have new or improved functions. Evolved enzymes can have a wide variety of uses in industry, agriculture or medicine.
Step 5: Using the improved enzyme
If you were working in David Ackerley’s lab, your screening test would be looking for an enzyme that can act on a prodrug to produce a toxic metabolite. If you found an efficient enzyme, it could be used in a new cancer treatment.
- 12 September 2008