PALB2 acetylation by KAT2A/B (GCN5/PCAF) in vitro

PArtner and Localizer of BRCA2 (PALB2) is essential to maintain genome stability in human cells. Upon DNA damage by double DNA strand breaks, PALB2 is required to repair DNA by homologous recombination. In undamaged conditions, PALB2 protects coding regions, by preventing DNA stress due to collisions between transcription and replication machineries. PALB2 associates with chromatin, which is essential to fulfill its function in genome stability maintenance, however molecular mechanisms regulating PALB2 chromatin association remain unknown. In our previous published study describing the KAT2A/B(GCN5/PCAF)-acetylome (Fournier et al., Nat.Comm. 2016, doi: 10.1038/ncomms13227) we have identified PALB2 as an acetylated protein target of the acetyltransferases KAT2A (GCN5) and KAT2B (PCAF) in vivo. KAT2A/B-acetylated sites of PALB2 were mapped within its DNA/Chromatin association domain. In this current study, we have conducted in vitro acetyltransferase (AT) assays, by mixing purified recombinant GST-tagged PALB2 full-length (FL) and PALB2 fragment P2.2 which associates with DNA/chromatin (from residues 295-610), with Flag-PCAF, Flag-GCN5 and Flag-GCN5 catalytic mutant (mut), followed by proteomics analysis to map PALB2 acetylated lysines by KAT2A(GCN5) and KAT2B(PCAF) in vitro. PALB2 FL and P2.2 alone, or PALB2 FL and P2.2 mixed with GCN5 catalytic mutant, were used as negative controls.