# Autophosphorylation of the Tousled-like kinases TLK1 and TLK2 regulates recruitment to damaged chromatin via PCNA interaction

## TL;DR

The study shows how autophosphorylation of TLK1 and TLK2 affects their recruitment to DNA damage sites through interaction with PCNA.

## Contribution

The study reveals that autophosphorylation of TLK1 and TLK2 inhibits their recruitment to DNA damage via masking a PCNA-interacting domain.

## Key findings

- TLK1 and TLK2 undergo hyper-autophosphorylation at their N-termini.
- TLK1 and TLK2 interact with PCNA via a conserved PIP-box.
- Autophosphorylation masks the PIP-box, preventing recruitment to DNA damage sites.

## Abstract

Tousled-like kinases 1 and 2 (TLK1 and 2) are cell cycle-regulated serine/threonine kinases that are involved in multiple biological processes. Mutation of TLK1 and 2 confer neurodegenerative diseases. Recent studies demonstrate that TLK1 and 2 are involved in DNA repair. However, there is no direct evidence that TLK1 and 2 function at DNA damage sites. Here, we show that both TLK1 and TLK2 are hyper-autophosphorylated at their N-termini, at least in part, mediated by their homo- or hetero- dimerization. We found that TLK1 and 2 hyper-autophosphorylation suppresses their recruitment to damaged chromatin. Furthermore, both TLK1 and 2 associate with PCNA specifically through their evolutionarily conserved non-canonical PCNA-interacting protein (PIP) box at the N-terminus, and mutation of the PIP-box abolishes their recruitment to DNA damage sites. Mechanistically, the TLK1 and 2 hyper-autophosphorylation masks the PIP-box and negatively regulates their recruitment to the DNA damage site. Overall, our study dissects the detailed genetic regulation of TLK1 and 2 at damaged chromatin, which provides important insights into their emerging roles in DNA repair.

Graphical Abstract