Identification and Characterization of the Chromatin-binding Domains of the HIV-1 Integrase Interactor LEDGF/p75

Integrase, LEDGF/p75 and HIV replication

“…The interaction between p75 and IN is direct [73] and it is confined to only one of the seven retroviral genera, lentivirinae [75,87,100]. A number of laboratories established the role of p75 in chromatin tethering, mapped relevant functional domains, and worked to answer the question of virological relevance [74][75][76][77][78][79][80][81][82][85][86][87][88][89][90][91]93,[95][96][97][100][101][102][103][104][105][108][109][110]. The first indication of the protein's significance was the clarification it provided about the vexing issue of the intracellular trafficking of retroviral integrase proteins.…”

“…On the amino-terminal end of the p75 tether, the situation is more complex but the first 198 amino acids of the protein contain a modular chromatin-binding ensemble [93] (Fig. 3).…”

“…The PWWP domain is found in numerous other nuclear proteins [134,135]. Deletion of this domain or just its beta-barrel sub-domain from p75 disrupts microscopically detectable tethering to condensed chromosomes [93]. There is some disagreement, however, since Turlure et al reported chromosome-tethering to be fully preserved after PWWP domain deletion [89].…”

“…There is some disagreement, however, since Turlure et al reported chromosome-tethering to be fully preserved after PWWP domain deletion [89]. Analyzed biochemically, deletion of the domain impairs high affinity (Triton X-100-refractory) chromatin binding, and additional deletion of the AT Hook domain abolishes it [93]. Similarly, the PWWP domain in conjunction with an adjacent segment of 49 relatively charged amino acids (CR1) is sufficient to tether GFP to condensed chromosomes, but transfer of Triton-resistant binding to GFP is negligible without addition of the AT hook pair [93].…”

“…Analyzed biochemically, deletion of the domain impairs high affinity (Triton X-100-refractory) chromatin binding, and additional deletion of the AT Hook domain abolishes it [93]. Similarly, the PWWP domain in conjunction with an adjacent segment of 49 relatively charged amino acids (CR1) is sufficient to tether GFP to condensed chromosomes, but transfer of Triton-resistant binding to GFP is negligible without addition of the AT hook pair [93]. Two additional charged regions (CR2 and CR3) in the N-terminal region also enhance the dominant activity of the PWWP and AT hook domains, with full Triton-resistance only achieved when the Nterminal donor to GFP extends all the way through CR2 [93].…”