AI Article Synopsis
- The integrase protein (IN) is crucial for integrating retroviral DNA into host chromosomes, and studies demonstrated that HIV-1 and HIV-2 IN proteins can efficiently facilitate this process.
- Both HIV IN proteins, despite only 53% similarity in their amino acid sequences, equally cut and integrate the viral DNA into target DNA.
- The mechanism is nuanced, as IN initially binds nonspecifically to DNA, but then shows specificity in cutting and integrating, suggesting that in a cellular context, IN is effectively positioned to work with viral DNA without interference from unrelated DNA.
Article Abstract
Integration of retroviral DNA into the host chromosome requires the integrase protein (IN). We overexpressed the IN proteins of human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2) in E. coli and purified them. Both proteins were found to specifically cut two nucleotides off the ends of linear viral DNA, and to integrate viral DNA into target DNA. This demonstrates that HIV IN is the only protein required for integration of HIV DNA. Although the two types of IN proteins have only 53% amino acid sequence similarity, they act with equal efficiency on both type 1 and type 2 viral DNA. Binding of IN to DNA was tested: purified IN does not bind very specifically to viral DNA ends. Nevertheless, only viral DNA ends are cleaved and integrated. We interpret this as follows: in vitro quick aspecific binding to DNA is followed by slow specific cutting and integration. IN can not find viral DNA ends in the presence of an excess of aspecific DNA; in vivo this is not required since the IN protein is in constant proximity of viral DNA in the viral core particle.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC328469 | PMC |
| http://dx.doi.org/10.1093/nar/19.14.3821 | DOI Listing |
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