Work

Polymerase θ is a robust terminal transferase that oscillates between three different mechanisms during end-joining

Year: 2016

Type: article

Abstract: DNA polymerase θ (Polθ) promotes insertion mutations during alternative end-joining (alt-EJ) by an unknown mechanism. Here, we discover that mammalian Polθ transfers nucleotides to the 3' terminus of DNA during alt-EJ in vitro and in vivo by oscillating between three different modes of terminal transferase activity: non-templated extension, templated extension in cis, and templated extension in trans. This switching mechanism requires manganese as a co-factor for Polθ template-independent activity and allows for random combinations of templated and non-templated nucleotide insertions. We further find that Polθ terminal transferase activity is most efficient on DNA containing 3' overhangs, is facilitated by an insertion loop and conserved residues that hold the 3' primer terminus, and is surprisingly more proficient than terminal deoxynucleotidyl transferase. In summary, this report identifies an unprecedented switching mechanism used by Polθ to generate genetic diversity during alt-EJ and characterizes Polθ as among the most proficient terminal transferases known.

Source: eLife

DOI: 10.7554/elife.13740

Authors: Tatiana Kent, Pedro A Mateos-Gomez, Agnel Sfeir, Richard T Pomerantz

Institutions: Temple University, New York University

Language: English

Topic: DNA Repair Mechanisms

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: gold

Estimated APC paid: $2,500

Funders: Temple University, National Institutes of Health, National Cancer Institute, National Institute of General Medical Sciences