title: Integrase-specific enhancement and suppression of retroviral DNA integration by compacted chromatin structure in vitro.
abstract: Integration of viral DNA into the host chromosome is an obligatory step in retroviral replication and is dependent on the activity of the viral enzyme integrase. To examine the influence of chromatin structure on retroviral DNA integration in vitro, we used a model target comprising a 13-nucleosome extended array that includes binding sites for specific transcription factors and can be compacted into a higher-ordered structure. We found that the efficiency of in vitro integration catalyzed by human immunodeficiency virus type 1 (HIV-1) integrase was decreased after compaction of this target with histone H1. In contrast, integration by avian sarcoma virus (ASV) integrase was more efficient after compaction by either histone H1 or a high salt concentration, suggesting that the compacted structure enhances this reaction. Furthermore, although site-specific binding of transcription factors HNF3 and GATA4 blocked ASV DNA integration in extended nucleosome arrays, local opening of H1-compacted chromatin by HNF3 had no detectable effect on integration, underscoring the preference of ASV for compacted chromatin. Our results indicate that chromatin structure affects integration site selection of the HIV-1 and ASV integrases in opposite ways. These distinct properties of integrases may also affect target site selection in vivo, resulting in an important bias against or in favor of integration into actively transcribed host DNA.
authors.affiliation: Fox Chase Cancer Center, Institute for Cancer Research, 333 Cottman Ave., Philadelphia, PA 19111-2497, USA.
authors.forename: Konstantin D
authors.initials: KD
authors.lastname: Taganov
authors.forename: Isabel
authors.initials: I
authors.lastname: Cuesta
authors.forename: René
authors.initials: R
authors.lastname: Daniel
authors.forename: Lisa Ann
authors.initials: LA
authors.lastname: Cirillo
authors.forename: Richard A
authors.initials: RA
authors.lastname: Katz
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Zaret
authors.forename: Anna Marie
authors.initials: AM
authors.lastname: Skalka
mesh_terms: D001358:Avian Sarcoma Viruses / Q000201:enzymology; D001665:Binding Sites; D002843:Chromatin / Q000737:chemistry / Q000821:virology*; D004268:DNA-Binding Proteins / Q000502:physiology; D050991:GATA4 Transcription Factor; D019427:HIV Integrase / Q000502:physiology; D051541:Hepatocyte Nuclear Factor 3-alpha; D019426:Integrases / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology; D009707:Nucleosomes / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics*; D014157:Transcription Factors / Q000502:physiology; D016662:Virus Integration
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D051541:Hepatocyte Nuclear Factor 3-alpha; D009687:Nuclear Proteins; D009707:Nucleosomes; D014157:Transcription Factors; D019427:HIV Integrase; D019426:Integrases