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Dr. Xiao Heng

University of Missouri – Department of Biochemistry

October 4, 2019 – Fall Seminar
Time and Location: 12 Noon in Meyerhoff Chemistry Building Room 120
Host: Dr. Mike Summers

Virus-Host interactions during the early stage of HIV-1 replication

DHX9/RHA are one of the cellular RNA-binding proteins that are incorporated into virions during human immunodeficiency virus type 1 (HIV-1) assembly and promote the replication efficiency of progeny virions. Virions deficient in RHA are less infectious as a result of reduced reverse transcription efficiency. The major goals of our studies are to investigate the structural basis of RHA co-assembly and the role of RHA in virions. Our cell-based experiments show that the truncation of segments of the HIV-1 5′-untranslated region (5′-UTR) distinct from the core encapsidation sequence eliminated virion incorporation of RHA, indicating that RHA recruitment is mediated by specific interactions with the HIV-1 5′-UTR. Consistently, biophysical assays reveal that the dsRNA binding domains of RHA preferentially binds to residues near the primer binding site. To investigate the role of virion-associated RHA in the early stage of replication, in vitro primer extension assays were established, and data show that RHA participates primarily in the elongation phase of reverse transcription. Pre-steady-state and steady-state kinetic studies suggest that RHA exert little impact on the kinetics of single-nucleotide incorporation by HIV-1 reverse transcriptase (RT), but significantly enhances the processivity RT. Our studies demonstrate that RHA co-assembles with viral RNA and serves as a processivity factor of RT during the early steps of viral replication.