title: The mechanism of H171T resistance reveals the importance of Nδ-protonated His171 for the binding of allosteric inhibitor BI-D to HIV-1 integrase.
abstract: BACKGROUND
  Allosteric HIV-1 integrase (IN) inhibitors (ALLINIs) are an important new class of anti-HIV-1 agents. ALLINIs bind at the IN catalytic core domain (CCD) dimer interface occupying the principal binding pocket of its cellular cofactor LEDGF/p75. Consequently, ALLINIs inhibit HIV-1 IN interaction with LEDGF/p75 as well as promote aberrant IN multimerization. Selection of viral strains emerging under the inhibitor pressure has revealed mutations at the IN dimer interface near the inhibitor binding site.
  
  
  RESULTS
  We have investigated the effects of one of the most prevalent substitutions, H171T IN, selected under increasing pressure of ALLINI BI-D. Virus containing the H171T IN substitution exhibited an ~68-fold resistance to BI-D treatment in infected cells. These results correlated with ~84-fold reduced affinity for BI-D binding to recombinant H171T IN CCD protein compared to its wild type (WT) counterpart. However, the H171T IN substitution only modestly affected IN-LEDGF/p75 binding and allowed HIV-1 containing this substitution to replicate at near WT levels. The x-ray crystal structures of BI-D binding to WT and H171T IN CCD dimers coupled with binding free energy calculations revealed the importance of the Nδ- protonated imidazole group of His171 for hydrogen bonding to the BI-D tert-butoxy ether oxygen and establishing electrostatic interactions with the inhibitor carboxylic acid, whereas these interactions were compromised upon substitution to Thr171.
  
  
  CONCLUSIONS
  Our findings reveal a distinct mechanism of resistance for the H171T IN mutation to ALLINI BI-D and indicate a previously undescribed role of the His171 side chain for binding the inhibitor.
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. slaughter.89@osu.edu.
authors.forename: Alison
authors.initials: A
authors.lastname: Slaughter
authors.affiliation: Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, MA, 02215, USA. kelliejurado@fas.harvard.edu.
authors.forename: Kellie A
authors.initials: KA
authors.lastname: Jurado
authors.affiliation: Department of Chemistry and Center for Biophysics and Computational Biology, College of Science and Technology, Temple University, Philadelphia, PA, 19122, USA. nanjie.deng@gmail.com.
authors.forename: Nanjie
authors.initials: N
authors.lastname: Deng
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. feng.203@osu.edu.
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. kessl.1@osu.edu.
authors.forename: Jacques J
authors.initials: JJ
authors.lastname: Kessl
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. shkriabai.1@osu.edu.
authors.forename: Nikoloz
authors.initials: N
authors.lastname: Shkriabai
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. larue.22@osu.edu.
authors.forename: Ross C
authors.initials: RC
authors.lastname: Larue
authors.affiliation: Department of Molecular Medicine & Division of Infectious Diseases, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA. fadel.hind@mayo.edu.
authors.forename: Hind J
authors.initials: HJ
authors.lastname: Fadel
authors.affiliation: Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA. pratiq.a.patel@vanderbilt.edu.
authors.forename: Pratiq A
authors.initials: PA
authors.lastname: Patel
authors.affiliation: Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA. jena.2@osu.edu.
authors.forename: Nivedita
authors.initials: N
authors.lastname: Jena
authors.affiliation: Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA. fuchs.42@osu.edu.
authors.forename: James R
authors.initials: JR
authors.lastname: Fuchs
authors.affiliation: Department of Molecular Medicine & Division of Infectious Diseases, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA. poeschla.eric@mayo.edu.
authors.forename: Eric
authors.initials: E
authors.lastname: Poeschla
authors.affiliation: Department of Chemistry and Center for Biophysics and Computational Biology, College of Science and Technology, Temple University, Philadelphia, PA, 19122, USA. tuf28314@temple.edu.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Levy
authors.affiliation: Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, MA, 02215, USA. alan_engelman@dfci.harvard.ed.
authors.forename: Alan
authors.initials: A
authors.lastname: Engelman
authors.affiliation: Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy, The Ohio State University, 496 W. 12th Ave, 508 Riffe Building, Columbus, OH, 43210, USA. kvaratskhelia.1@osu.edu.
authors.forename: Mamuka
authors.initials: M
authors.lastname: Kvaratskhelia
mesh_terms: D000085:Acetates / Q000378:metabolism*; D002460:Cell Line; D018360:Crystallography, X-Ray; D024882:Drug Resistance, Viral; D019427:HIV Integrase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019428:HIV Integrase Inhibitors / Q000378:metabolism*; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology*; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D011485:Protein Binding; D011487:Protein Conformation; D011804:Quinolines / Q000378:metabolism*
chemical_list: D000085:Acetates; C578374:BI-D compound; D019428:HIV Integrase Inhibitors; D050505:Mutant Proteins; D011804:Quinolines; D006639:Histidine; D019427:HIV Integrase; C514801:p31 integrase protein, Human immunodeficiency virus 1