Format

Send to

Choose Destination
Virology. 2003 Sep 15;314(1):460-7.

Roles of host cell factors in circularization of retroviral dna.

Author information

1
Infectious Disease Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.

Abstract

Early during retroviral infection, a fraction of the linear reverse-transcribed viral DNA genomes become circularized by cellular enzymes, thereby inactivating the genomes for further replication. Prominent circular DNA forms include 2-long-terminal repeat (LTR) circles, made by DNA end joining, and 1-LTR circles, produced in part by homologous recombination. These reactions provide a convenient paradigm for analyzing the cellular machinery involved in DNA end joining in vertebrate cells. In previous studies, we found that inactivating components of the nonhomologous DNA end-joining (NHEJ) pathway--specifically Ku, ligase 4, or XRCC4--blocked formation of 2-LTR circles. Here we report that inactivating another NHEJ component, the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), had at most modest effects on 2-LTR circle formation, providing informative parallels with other end-joining reactions. We also analyzed cells mutant in components of the RAD50/MRE11/NBS1 nuclease and found a decrease in the relative amount of 1-LTR circles, opposite to the effects of NHEJ mutants. In MRE11-mutant cells, a MRE11 gene mutant in the nuclease catalytic site failed to restore 1-LTR circle formation, supporting a model for the role of MRE11 in 1-LTR circle formation. None of the cellular mutations showed a strong effect on normal integration, consistent with the idea that the cellular pathways leading to circularization are not involved in productive integration.

PMID:
14517098
DOI:
10.1016/s0042-6822(03)00455-0
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center