Identification of a Candidate Rad1 Subunit for the Kinetoplastid 9-1-1 (Rad9-Hus1-Rad1) Complex

The trimeric 9-1-1 (Rad9-Hus1-Rad1) complex plays an important role in the eukaryotic DNA damage response by recruiting DNA repair factors and checkpoint mediators to damaged sites. Extensively characterised in mammals and yeast, evidence is now emerging that 9-1-1 function is conserved beyond the relatively narrow evolutionary range of the Opisthokonts. Kinetoplastid Rad9 and Hus1 proteins have been identified and shown to be involved in the DNA damage response but Rad1 has remained elusive. In this study, PSI-BLAST iterative database searching, phylogenetic and structural modeling techniques are used to identify and characterise candidate Rad1 proteins in kinetoplastid organisms.