Part families are a great asset to the Parts Registry. Our process for expanding basic parts into part families is quick, easy, and prioritizes the use of materials that most iGEM teams already have on hand. By following these steps, you can improve the utility of your favorite part and help build a strong foundation of useful parts for synthetic biologists around the world.

Our Method

Our part family expansion process is broken down into four major steps:

Selection: Choose your basic part of interest and obtain a DNA sample.
Mutagenesis: Create a library of mutants from your basic part.
Screening: Select a range of mutants that will offer the most utility for future projects.
Characterization: Collect detailed information on each mutant to document its behavior.

Selection

The Parts Registry has a wide selection of basic parts that are good candidates for part family expansion. This includes promoters, repressors, reporter proteins, and many others. For our process to work properly, selected parts must contain standard VF2 and VR sites around the region of interest.

Ideal parts are around 200 base pairs or more in length, as smaller parts show reduced levels of transformation success. Part selection is also key to the success of later screening and characterization steps: measuring the activity of parts often requires the use of a fluorescent reporter like GFP, so your parts must affect the expression of this reporter in some way. For example, promoter mutants can be used to transcribe different levels of reporter mRNA, and differences in the activity of reporter mutants can be measured directly.

We also recommend that parts be selected with their future utility in mind -- we chose to work with repressible promoters because they are frequently used in designing genetic circuits. This will help frame the paramater space over which mutants will be selected for final characterization, and helps judge the amount of mutagenesis required to achieve good mutant library resolution.