In the paper posted on the Web site of The EMBO Journal, an official journal of the European Molecular Biology Organization, the researchers describe how DNA polymerase Q, or POL-Q, has the exceptional ability to bypass damaged spots in the DNA sequence that are caused by a cell's normal wear and tear or other abuses. In addition, it is the only known enzyme that orchestrates not only one, but two steps involved in bypassing common types of DNA damage.
POL-Q is one of 15 different DNA polymerases in human cells. These specialized enzymes carry out the duplication, proofreading and repair of DNA. DNA is a double-stranded molecule that contains genes necessary for the production of proteins, which in turn determine all aspects of a cell's structure, function and movement. Each strand consists of nucleotides with any combination of four nitrogen-containing bases A, T, C and G, for short that when in proper sequence are paired with those on the opposing, complementary strand. About 1,000 nucleotides are copied per second, and mistakes in the process are rare. Problems in the sequence sometimes arise, such as a wrong or missing base or one that is damaged. If a problem somehow evades detection, it can prevent DNA from being replicated or result in a mutation in the copied DNA.