Natl Conf Hum Retroviruses Relat Infect (1st). 1993 Dec 12-16;:126.
Analysis of amino acid sequences of a number of retroviral integrases
have demonstrated the presence of conserved motifs that may be important
for integrase activity. The most highly conserved region is the middle
part of protein, known as the D,D(35)E region, that is believed to
contain the catalytic site of integrase. In order to analyze effects of
integrase point mutations on viral protein synthesis, virion
morphogenesis, and viral replication, point mutations in selected amino
acids in the central region of HIV-1 integrase were introduced. Nine
integrase point mutants of the infectious molecular clone pHXBc2 were
constructed. We observed: 1) mutation of two amino acids that are
invariant among retroviral integrases, E152 and D116, as well as
mutation of the highly conserved amino acid S147, blocked viral
replication in two CD4+ human T cell lines; 2) mutations of four other
highly conserved amino acids in the region had no effect on viral
replication, whereas mutations at two positions, N117 and Y143, resulted
in viruses with delayed replication phenotypes; 3) defects in virion
precursor polypeptide processing, virion morphology, or viral DNA
synthesis were observed for all of the replication-defective mutants.
These data suggest that mutant integrase proteins can interfere with a
variety of steps in the early and late stages of viral replication
cycle. Integrase mutations must be carefully assessed for their effects
on all aspects of viral replication before a particular phenotype can be
assigned to a specific defect in integrase function. We are now
establishing stable virus- producing cell lines for all of the
replication-defective mutants in order to analyze their effects on the
rate of viral DNA synthesis, viral DNA end processing, nuclear entry and
formation of circular viral DNA to pinpoint the basis of the altered
phenotypes.
Cell Line CD4-Positive T-Lymphocytes/VIROLOGY *DNA
Nucleotidyltransferases/*GENETICS Human HIV-1/*ENZYMOLOGY/PHYSIOLOGY
Phenotype Point Mutation Virus Replication ABSTRACT