Allosteric Inhibition of Human Immunodeficiency Virus Type 1 Reverse Transcriptase by Tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione Compounds

The reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is present in virions and infected cells as an heterodimer (p66/p51). A new class of potent and selective HIV-1 inhibitors, the tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione (TIBO) derivatives, were found to exert their antiviral activity by interacting with monomeric HIV-1 RT (p66) in a way different from that of previously studied RT inhibitors such as azidothymidine 5'-triphosphate. Upon examination of the kinetic properties of the heterodimeric HIV-1 RT and its inhibition by TIBO compounds, a positive cooperativity between the subunits of the enzyme with regard to the 2'-deoxynucleoside 5'-triphosphates and the template/primer was observed. The cooperativity with respect to the template/primer may result from a progressive dimerization in the presence of increasing concentrations of the template/primer, a process referred to as polysteric linkage. Because the cooperativity of p66/p51 was abolished in the presence of TIBO, these compounds behave as allosteric inhibitors.