Biology subjects

Towle-Weicksel, J. B.

Publications and source records attributed to Towle-Weicksel, J. B..

2 recordsLinked to original sources

bioRxiv2024

Zebrafish Pol-Theta and Human Pol-Theta, Orthologues with Homologous Function

DNA Polymerase Theta (Pol {theta}) is a conserved an A-family polymerase that plays an essential role in repairing double strand breaks, through micro-homology end joining, and bypassing DNA lesions, through translesion synthesis, to protect genome integrity. Despite its essential role in DNA repair, Pol {theta} is inherently error-prone. Recently, key loop regions were identified to play an important role in key functions of Pol {theta}. Here we present a comparative structure-function study of the polymerase domain of zebrafish and human Pol {theta}. We show that these two proteins share a large amount of sequence and structural homology. However, we identify differences in the amino acid composition within the key loop areas shown to drive characteristic Pol {theta} functions. Despite these differences zebrafish Pol {theta} still displays characteristics identify in human Pol {theta}, including DNA template extension in the presence of different divalent metals, microhomology-mediated end joining, and translesion synthesis. These results will support future studies looking to gain insight into Pol {theta} function on the basis of evolutionarily conserved features.

molecular biology↗

bioRxiv2023

Melanoma-derived DNA polymerase theta variants exhibit altered DNA polymerase activity

DNA Polymerase {theta} (Pol {theta} or POLQ) is primarily involved in repairing double-stranded breaks in DNA through the alternative pathway known as microhomology-mediated end joining (MMEJ) or theta-mediated end joining (TMEJ). Unlike other DNA repair polymerases, Pol {theta} is thought to be highly error prone, yet critical for cell survival. We have identified several mutations in the POLQ gene from human melanoma tumors. Through biochemical analysis, we have demonstrated that all three cancer-associated variants experienced altered DNA polymerase activity including a propensity for incorrect nucleotide selection and reduced polymerization rates compared to WT Pol {theta}. Moreover, the variants are 30 fold less efficient at incorporating a nucleotide during repair and up to 70 fold less accurate at selecting the correct nucleotide opposite a templating base. Taken together, this suggests that aberrant Pol {theta} has reduced DNA repair capabilities and may also contribute to increased mutagenesis. While this may be beneficial to normal cell survival, the variants were identified in established tumors suggesting that cancer cells may use this promiscuous polymerase to its advantage to promote metastasis and drug resistance.

biochemistry↗