A mutation in integrase can compensate for mutations in the simian immunodeficiency virus att site

Abstract

Sequences at the left terminus of U3 in the left long terminal repeat (LTR) and at the right terminus of U5 in the right LTR are important for integration of retroviral DNA. In the infectious pathogenic molecular clone of simian immunodeficiency virus strain mac239 (SIVmac239), 10 of the 12 terminal base pairs form an imperfect inverted repeat structure (5 TGGAAGGGATTT 3 [nucleotides 1 to 12] and 3 ACGATCCCTAAA 5 [nucleotides 10279 to 10268]). Nineteen different mutant forms of SIVmac239 proviral DNA with changes at one or more of the positions in each of the 12-terminal-base-pair regions were constructed. Viral replication was severely or completely compromised with nine of these mutants. Revertants appeared 40 to 50 days after transfection in two independent experiments with mutant 7, which contained changes of AGG to TAC at positions 5 to 7 in U3 and TCC to GAA at positions 10275 to 10273 in U5. Virus produced at these times from mutant 7 transfection replicated upon reinfection with only a slight delay when compared to the wild type. Sequence analysis of the LTR and integrase regions from infected cultures revealed two predominant changes:G to A at position 10275 in U5 and Glu to Lys at position 136 in integrase. Derivatives of clone 7 in which these changes were introduced individually and together were constructed by site-specific mutagenesis. Each change individually restored replication capacity only partially. However, the combination of both mutations restored replicative capacity to that of the original revertants. These results indicate that changes in integrase can compensate for mutations in the terminal nucleotides of the SIV LTR. The results further indicate that resistance to integrase inhibitors may include both integrase and LTR mutations.

Mapping Viral DNA Specificity to the Central Region of Integrase by Using Functional Human Immunodeficiency Virus Type 1/Visna Virus Chimeric Proteins

“…For example, there is biochemical evidence that Lys-136 and Lys-159 can interact with viral DNA (27,51). Moreover, recent genetic studies showed that a mutation in simian immunodeficiency virus IN at the position analogous to Lys-136 in HIV-1 IN can compensate for mutations near the viral DNA termini (14).…”

Specific and Independent Recognition of U3 and U5 att Sites by Human Immunodeficiency Virus Type 1 Integrase In Vivo

“…Combined with these in vitro studies, further experiments using the in vivo system are necessary for new insight into retroviral integration. Interestingly, the recent studies of Du et al (14) showed that a mutation in IN can compensate for mutations in simian immunodeficiency virus att.…”

“…These in vitro studies have greatly increased our understanding of the molecular mechanism of retroviral integration. However, recent studies (14,19,34,38,45) have indicated some differences or discrepancies between results of in vitro and in vivo assays. These discrepancies may reflect differences due to experimental conditions between in vitro and in vivo conditions.…”

Structure-Based Mutagenesis of the Human Immunodeficiency Virus Type 1 DNA Attachment Site: Effects on Integration and cDNA Synthesis

“…2). Mutants 1A2, 1B1, and 1B2 contained the same base changes as those previously studied in SIV (9). Whereas compensatory changes were incorporated into mutant 1B1 at U5 positions 43 to 45, these upstream bases were left unchanged in mutant 1B2.…”

“…Positions 5 to 7 from each terminus have been shown to be important for simian immunodeficiency virus (SIV) integration in infected cells (9). Mutants 1A1, 1A2, 1B1, and 1B2 targeted these sequences in HIV-1 (Fig.…”