title: Initiation complex dynamics direct the transitions between distinct phases of early HIV reverse transcription.
abstract: Human immunodeficiency virus (HIV) initiates reverse transcription of its viral RNA (vRNA) genome from a cellular tRNA(3)(Lys) primer. This process is characterized by a slow initiation phase with specific pauses, followed by a fast elongation phase. We report a single-molecule study that monitors the dynamics of individual initiation complexes, comprised of vRNA, tRNA and HIV reverse transcriptase (RT). RT transitions between two opposite binding orientations on tRNA-vRNA complexes, and the prominent pausing events are related to RT binding in a flipped orientation opposite to the polymerization-competent configuration. A stem-loop structure within the vRNA is responsible for maintaining the enzyme predominantly in this flipped orientation. Disruption of the stem-loop structure triggers the initiation-to-elongation transition. These results highlight the important role of the structural dynamics of the initiation complex in directing transitions between early reverse transcription phases.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, USA.
authors.forename: Shixin
authors.initials: S
authors.lastname: Liu
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Harada
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Miller
authors.forename: Stuart F J
authors.initials: SF
authors.lastname: Le Grice
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Zhuang
mesh_terms: D004247:DNA / Q000096:biosynthesis; D031541:Fluorescence Resonance Energy Transfer; D015497:HIV-1 / Q000235:genetics*; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D012367:RNA, Viral / Q000737:chemistry*; D012194:RNA-Directed DNA Polymerase / Q000502:physiology; D048348:Reverse Transcription / Q000502:physiology*; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D004247:DNA; D012194:RNA-Directed DNA Polymerase