INI1/SMARCB1 Rpt1 domain mimics TAR RNA in binding to integrase to facilitate HIV-1 replication.
Dixit, U., Bhutoria, S., Wu, X., Qiu, L., Spira, M., Mathew, S., Harris, R., Adams, L.J., Cahill, S., Pathak, R., Rajesh Kumar, P., Nguyen, M., Acharya, S.A., Brenowitz, M., Almo, S.C., Zou, X., Steven, A.C., Cowburn, D., Girvin, M., Kalpana, G.V.(2021) Nat Commun 12: 2743-2743
- PubMed: 33980829 
- DOI: https://doi.org/10.1038/s41467-021-22733-9
- Primary Citation of Related Structures:  
6AX5 - PubMed Abstract: 
INI1/SMARCB1 binds to HIV-1 integrase (IN) through its Rpt1 domain and exhibits multifaceted role in HIV-1 replication. Determining the NMR structure of INI1-Rpt1 and modeling its interaction with the IN-C-terminal domain (IN-CTD) reveal that INI1-Rpt1/IN-CTD interface residues overlap with those required for IN/RNA interaction. Mutational analyses validate our model and indicate that the same IN residues are involved in both INI1 and RNA binding. INI1-Rpt1 and TAR RNA compete with each other for IN binding with similar IC 50 values. INI1-interaction-defective IN mutant viruses are impaired for incorporation of INI1 into virions and for particle morphogenesis. Computational modeling of IN-CTD/TAR complex indicates that the TAR interface phosphates overlap with negatively charged surface residues of INI1-Rpt1 in three-dimensional space, suggesting that INI1-Rpt1 domain structurally mimics TAR. This possible mimicry between INI1-Rpt1 and TAR explains the mechanism by which INI1/SMARCB1 influences HIV-1 late events and suggests additional strategies to inhibit HIV-1 replication.
Organizational Affiliation: 
Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA.