Human single-stranded DNA-binding protein 1 (hSSB1) plays an important role in the DNA damage response and the maintenance of genomic stability. It has been shown that the core hSSB1 complex contains hSSB1, INTS3 and C9orf80. Using protein affinity purification, we have identified integrator complex subunit 6 (INTS6) as a major subunit of the core hSSB1 complex. INTS6 forms a stable complex with INTS3 and hSSB1 both in vitro and in vivo. In this complex, INTS6 directly interacts with INTS3. In response to the DNA damage response, along with INTS3 and hSSB1, INTS6 relocates to the DNA damage sites. Moreover, the hSSB1-INTS complex regulates the accumulation of RAD51 and BRCA1 at DNA damage sites and the correlated homologous recombination.
Keywords: DNA damage response; Homologous recombination; hSSB1–INTS complex.