Structural Description
Full length polymerase theta consists of an N-terminal helicase-like domain that is connected to the C-terminal polymerase domain by a central linker region.
Image:Full-lengthpoltheta
The polymerase domain of polymerase theta (QM1) is a member of the A-family of polymerases which includes Pol I and T7 DNA polymerase. A-family polymerases contain
Structural Insights
Function
Polymerase theta is a DNA double strand break repair protein. Double strand breaks can occur as a result of both exogenous (ionizing radiation) and endogenous (reactive oxygen species, replication fork collapse) damage. To repair breaks, polymerase theta employs theta-mediated end-joining (TMEJ), which is a form of alternative end-joining (altEJ). TMEJ begins with pairing of microhomologies in 3' single stranded overhangs that have been exposed through 5' end resectioning at the site of the break. If the microhomologies are internal to the 3' end of the overhanging DNA, the resulting flaps will be removed and a deletion will be introduced. If microhomologies arise from brief templated synthesis with a more distant strand, insertions will occur. Once microhomologies are aligned, pol theta synthesizes DNA to fill the gaps on either side of the microhomologies.
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References
You may include any references to papers as in: the use of JSmol in Proteopedia [1] or to the article describing Jmol [2] to the rescue.
