New methods for studying DNA repair and protein modification

This month's issue of Cold Spring Harbor Protocols features two articles detailing experimental methods for the analysis of molecular processes involved in DNA repair and post-translational modification of proteins.

Homologous recombination is an important mechanism for the repair of damaged chromosomes. When this occurs, a Displacement Loop, or "D-loop," is formed as the two strands of the DNA molecule are separated and held apart by a third strand of DNA. Patrick Sung's laboratory at Yale University has detailed a method for generating these structures in their article, "Assay for Human Rad51-Mediated DNA Displacement Loop Formation." This reconstituted system provides researchers a biochemical means to dissect the mechanisms of the homologous recombination machinery. The protocol is freely accessible on the website for Cold Spring Harbor Protocols.

Sumoylation involves the attachment of Small Ubiquitin-like Modifier or "SUMO" proteins to other proteins in a cell. Sumoylation modifies these target proteins and can affect a variety of activities, including stability, transport, and transcriptional regulation. James Manley's laboratory at Columbia University provides "In Vitro Sumoylation of Recombinant Proteins and Subsequent Purification for Use in Enzymatic Assays," a protocol for modifying proteins in this manner, allowing one to assess the impact of sumoylation. This method is freely accessible on the website for Cold Spring Harbor Protocols.