Model for the role of NBS1 in post-integration repair. Integrase catalyzes formation of the integration intermediate (1). NBS1 and ATR are recruited independently to the integration sites (2). NBS1 then recruits MRE11, RAD50 and ATM. (3). The 5'-end DNA flaps of the viral DNA are trimmed, possibly by MRN. ATM phosphorylates H2AX. However, H2AX phosphorylation is not required for post-integration repair. (4). We speculate that Artemis and NHEJ proteins are recruited to the integration site (5). These proteins, and likely other factors, then mediate the other steps of post integration repair, which require possibly further end processing, gap filling, ligation and chromatin remodeling (6).
Smith et al. Virology Journal 2008 5:11 doi:10.1186/1743-422X-5-11