American Society for Biochemistry and Molecular Biology
Journal of Biological Chemistry vol:287 issue:4 pages:34059-34068
Transportin-SR2 (TRN-SR2, TNPO3) is a cellular cofactor of HIV replication that has been implicated in the nuclear import of HIV. TRN-SR2 was originally identified in a yeast two-hybrid screen as an interaction partner of HIV integrase (IN) and in two independent siRNA screens as a co-factor of viral replication. We now studied the interaction of TRN-SR2 and HIV IN in molecular detail and identified the TRN-SR2 interacting regions of IN. A weak interaction with the catalytic core domain (CCD) and a strong interaction with the C-terminal domain (CTD) of IN were detected. By dissecting the catalytic core domain (CCD) of IN into short structural fragments we identified a peptide (INIP1, aa 170-EHLKTAVQMAVFIHNFKRKGGI-191) retaining the ability to interact with TRN-SR2. By dissecting the C-terminal domain (CTD) of IN we could identify two interacting peptides (aa 214-QKQITKIQNFRVYYR-229 and 262-RRKVKIIRDYGK-274) that come together in the CTD tertiary structure to form an exposed antiparallel β-sheet. Through site specific mutagenesis we defined following sets of amino acids in IN as important for the interaction with TRN-SR2: F185/K186/R187/K188 in the CCD and R262/R263/K264 and K266/R269 in the CTD. An HIV-1 strain carrying K266A/R269A in IN was replication defective due to a block in reverse transcription, confounding the study of nuclear import. Insight into the IN/TRN-SR2 interaction interface is necessary to guide drug discovery efforts targeting the nuclear entry step of replication.