The recombination of DNA has proven to be an effective strategy for the engineering new and desired properties into proteins. In particular, methods for the creation of combinatorial libraries of proteins coupled with methods for identifying functional members in these libraries are very powerful at improving a protein's properties. However, the vast majority of these combinatorial methods for creating libraries are homology-dependent in that they only create crossovers between genes in regions of high homology. The application of incremental truncation, a DNA homology-independent method that creates a library of every possible integer base truncation of a gene, to protein engineering will be explored. They are both experiencing the consequences of misfolded proteins, known as prions.
Proteins are complex polymers composed of twenty different amino acids.
For a protein to function properly, it must be folded into just the right shape. When proteins misfold, cells usually get rid of them. A few proteins, known as prions, misfold in a manner that influences other protein of the same type to misfold in the same way. Although this process is still somewhat controversial in mammals, a similar process has been demonstrated to operate in yeast cells beyond a reasonable doubt. Here, the misfolding event doesn't cause disease, but instead changes the metabolism of the cell.