THE IN-VITRO EJECTION OF ZINC FROM HUMAN-IMMUNODEFICIENCY-VIRUS (HIV)TYPE-1 NUCLEOCAPSID PROTEIN BY DISULFIDE BENZAMIDES WITH CELLULAR ANTI-HIV ACTIVITY
Pj. Tummino et al., THE IN-VITRO EJECTION OF ZINC FROM HUMAN-IMMUNODEFICIENCY-VIRUS (HIV)TYPE-1 NUCLEOCAPSID PROTEIN BY DISULFIDE BENZAMIDES WITH CELLULAR ANTI-HIV ACTIVITY, Proceedings of the National Academy of Sciences of the United Statesof America, 93(3), 1996, pp. 969-973
Several disulfide benzamides have been shown to possess wide-spectrum
antiretroviral activity in cell culture at low micromolar to submicrom
olar concentrations, inhibiting human immunodeficiency virus (HIV) typ
e 1 (HIV-1) clinical and drug-resistant strains along with HIV-2 and s
imian immunodeficiency virus [Rice, W. G., Supko, J. G., Malspeis, L.,
Buckheit, R. W., Jr., Clanton, D., Bu, M., Graham, L., Schaeffer, C.
A., Turpin, J. A., Domagala, J., Gogliotti, R., Bader, J. P., Halliday
, S. M., Coren, L., Sowder, R. C., II, Arthur, L. O. & Henderson, L. E
. (1995) Science 270, 1194-1197]. Rice and coworkers have proposed tha
t the compounds act by ''attacking'' the two zinc fingers of HIV nucle
ocapsid protein. Shown here is evidence that low micromolar concentrat
ions of the anti-HIV disulfide benzamides eject zinc from HIV nucleoca
psid protein (NCp7) in vitro, as monitored by the zinc-specific fluore
scent probe N-(6-methoxy-8-quinoyl)-p-toluenesulfonamide (TSQ). Struct
urally similar disulfide benzamides that do not inhibit HIV-1 in cultu
re do not eject zinc, nor do analogs of the antiviral compounds with t
he disulfide replaced with a methylene sulfide. The kinetics of NCp7 z
inc ejection by disulfide benzamides were found to be nonsaturable and
biexponential, with the rate of ejection from the C-terminal zinc fin
ger 7-fold faster than that from the N-terminal. The antiviral compoun
ds were found to inhibit the zinc-dependent binding of NCp7 to HIV psi
RNA, as studied by gel-shift assays, and the data correlated well wit
h the zinc ejection data. Anti-HIV disulfide benzamides specifically e
ject NCp7 zinc and abolish the protein's ability to bind psi RNA in vi
tro, providing evidence for a possible antiretroviral mechanism of act
ion of these compounds. Congeners of this class are under advanced pre
clinical evaluation as a potential chemotherapy for acquired immunodef
iciency syndrome.