DNA Polymerase Theta

<Structure load='4x0p' size='350' frame='true' align='right' caption='DNA polymerase theta polymerase domain in complex with double-stranded DNA substrate and incoming ddATP' >

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. File: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 6 conserved motifs

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

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Proteopedia Page Contributors and Editors (what is this?)

Lea Drogalis, Michal Harel, Jaime Prilusky