V. Ellison et al., AN ESSENTIAL INTERACTION BETWEEN DISTINCT DOMAINS OF HIV-1 INTEGRASE MEDIATES ASSEMBLY OF THE ACTIVE MULTIMER, The Journal of biological chemistry, 270(7), 1995, pp. 3320-3326
Integrase mediates integration of the retroviral genome into a host ce
ll chromosome, an essential step in the viral life cycle. In vitro, a
stable complex containing only purified human immunodeficiency virus (
HIV) integrase and a model viral DNA substrate processively executes t
he S'-end processing and DNA joining steps in the integration reaction
. We examined the relationship of three essential components of the HI
V integrase: the HHCC domain, a putative zinc-finger near the N termin
us; the phylogenetically conserved ''DD35E'' motif, which defines the
catalytic domain; and a feature recognized by its sensitivity to the a
lkylating agent N-ethylmaleimide (NEM). HIV integrase is a multimer, a
nd these three components can be distributed among at least two subuni
ts of the multimeric enzyme. The components function asymmetrically in
the active multimer; the DD35E motif and NEM-sensitive site are requi
red in trans to the HHCC region. A divalent cation-dependent interacti
on involving the NEM-sensitive site of one integrase subunit and the H
HCC region of another subunit points to a role for these two features
of integrase in multimer assembly. Deletion of the HHCC domain, or mod
ification of integrase with NEM, impaired the assembly of a stable com
plex between integrase and viral DNA, suggesting that this initial ste
p in the integration pathway requires assembly of the active integrase
multimer.