scholarly journals Structural Characterization of the HIV-1 Reverse Transcriptase Initiation Complex

2018 ◽  
Vol 114 (3) ◽  
pp. 193a
Author(s):  
Kevin Larsen ◽  
Yamuna Mathiharan ◽  
Kalli Kappel ◽  
Aaron Coey ◽  
Dong-Hua Chen ◽  
...  
1985 ◽  
Vol 260 (14) ◽  
pp. 8243-8249 ◽  
Author(s):  
D Grandgenett ◽  
T Quinn ◽  
P J Hippenmeyer ◽  
S Oroszlan

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Betty Ha ◽  
Kevin P. Larsen ◽  
Jingji Zhang ◽  
Ziao Fu ◽  
Elizabeth Montabana ◽  
...  

AbstractReverse transcription of the HIV-1 viral RNA genome (vRNA) is an integral step in virus replication. Upon viral entry, HIV-1 reverse transcriptase (RT) initiates from a host tRNALys3 primer bound to the vRNA genome and is the target of key antivirals, such as non-nucleoside reverse transcriptase inhibitors (NNRTIs). Initiation proceeds slowly with discrete pausing events along the vRNA template. Despite prior medium-resolution structural characterization of reverse transcriptase initiation complexes (RTICs), higher-resolution structures of the RTIC are needed to understand the molecular mechanisms that underlie initiation. Here we report cryo-EM structures of the core RTIC, RTIC–nevirapine, and RTIC–efavirenz complexes at 2.8, 3.1, and 2.9 Å, respectively. In combination with biochemical studies, these data suggest a basis for rapid dissociation kinetics of RT from the vRNA–tRNALys3 initiation complex and reveal a specific structural mechanism of nucleic acid conformational stabilization during initiation. Finally, our results show that NNRTIs inhibit the RTIC and exacerbate discrete pausing during early reverse transcription.


1989 ◽  
Vol 23 (suppl A) ◽  
pp. 47-54 ◽  
Author(s):  
M. Tisdale ◽  
B. A. Larder ◽  
D. M. Lowe ◽  
D. K. Stammers ◽  
D. J. M. Purifoy ◽  
...  

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 114
Author(s):  
R. Elliot Murphy ◽  
Alexandra B. Samal ◽  
Gunnar Eastep ◽  
Ruba H. Ghanam ◽  
Peter E. Prevelige ◽  
...  

During the late phase of the HIV-1 replication cycle, the Gag polyproteins are transported to the plasma membrane (PM) for assembly. Gag targeting and assembly on the PM is dependent on interactions between its matrix (MA) domain and phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Subsequent to Gag assembly, the envelope (Env) protein is recruited to the PM for incorporation into virus particles. Evidence suggests that the incorporation of the Env protein is mediated by interactions between the MA domain of Gag and the cytoplasmic tail of the gp41 subunit of Env (gp41CT), a mechanism that remains to be elucidated. Trimerization of the MA domain of Gag appears to be an obligatory step for this interaction. The interplay between gp41CT, the MA trimer, and the membrane has yet to be determined. Our lab has pioneered methods and approaches to investigate, at the molecular level, how the retroviral MA domains of Gag interact with membranes, a key requirement for understanding the Gag assembly and Env incorporation. Herein, we devised innovative approaches that will enable the structural characterization of the gp41CT–MA–membrane interactions. We employed structural biology (NMR and cryo-electron microscopy, biophysical methods, and biochemical tools to generate a macromolecular picture of how the MA domain of Gag binds to the membrane and how it interacts with gp41CT. To this end, we: (i) determined the three-dimensional structure of HIV-1 gp41CT and characterized its interaction with the membrane, (ii) engineered trimeric constructs of gp41CT and the MA to recapitulate the native and functional states of the proteins, and (iii) utilized membrane nanodisc technology to anchor the MA and gp41CT proteins. Our studies will allow for a detailed structural characterization of the gp41CT–MA–membrane interactions, which will advance our knowledge of HIV-1 Gag assembly and Env incorporation.


1994 ◽  
Vol 5 (4) ◽  
pp. 278-281
Author(s):  
H. Samanta ◽  
R. Rose ◽  
A. K. Patick ◽  
C. M. Bechtold ◽  
J. Trimble ◽  
...  

A virus strain resistant to R82150, a non-nucleoside reverse transcriptase (NNRT) inhibitor (tetrahydro-imidazo [4,5, 1- jk] [1,4] benzodiazepine-2(1 H)-thione), was isolated following serial passage of HIV-1 RF in CEM-SS cells. The virus is cross-resistant to another non-nucleoside reverse transcriptase inhibitor, TGG-II-23A [1,4-dimethyl-1-[5,5-dimethyl-2-oxazoionyl]-naphthalen-2-one), but remains susceptible to AZT, DDI, D4T and phosphonoformate (PFA). DNA sequencing of reverse transcriptase genes from resistant virus indicated that R82150 selects for amino acid alterations Y181C and V108I. In vitro mutagenized reverse transcriptase and recombinant HIV-1 (pNL4-3) carrying either of the mutations have been generated. Genotypic and phenotypic analyses identified V108I as an unreported R82150-associated mutation. Both reverse transcriptase and viral resistance assays indicated that the resistance conferred by the V108I mutation is 7-fold less than that conferred by Y181C.


2020 ◽  
Vol 94 (17) ◽  
Author(s):  
Maolin Lu ◽  
Xiaochu Ma ◽  
Nick Reichard ◽  
Daniel S. Terry ◽  
James Arthos ◽  
...  

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer of gp120-gp41 heterodimers mediates virus entry into CD4-positive (CD4+) cells. Single-molecule fluorescence resonance energy transfer (smFRET) has revealed that native Env on the surface of viruses predominantly exists in a pretriggered conformation (state 1) that is preferentially recognized by many broadly neutralizing antibodies (bNAbs). Env is activated by binding receptor CD4, which drives transitions through a default intermediate conformation (state 2) into the three-CD4-bound open conformation (state 3). The application of smFRET to assess the conformational state of existing Env constructs and ligand complexes recently revealed that all current high-resolution structures correspond to downstream states 2 and 3. The structure of state 1, therefore, remains unknown. We sought to identify conditions whereby HIV-1 Env could be stabilized in the pretriggered state 1 for possible structural characterization. Shedding of gp120, known to severely complicate structural studies, can be prevented by using the uncleaved gp160JR-FL precursor with alterations in the protease cleavage site (R508S/R511S) or by introducing a disulfide bridge between gp120 and gp41 designated “SOS” (A501C/T605C). smFRET demonstrated that both shedding-preventing modifications shifted the conformational landscape of Env downstream toward states 2 and 3. However, both membrane-bound Env proteins on the surface of intact viruses remained conformationally dynamic, responsive to state-stabilizing ligands, and able to be stabilized in state 1 by specific ligands such as the Bristol-Myers Squibb (BMS) entry inhibitors. The here-described identification of state 1-stabilizing conditions may enable structural characterization of the state 1 conformation of HIV-1 Env. IMPORTANCE The HIV-1 envelope glycoprotein (Env) opens in response to receptor CD4 binding from a pretriggered (state 1) conformation through a necessary intermediate to the three-CD4-bound conformation. The application of smFRET to test the conformational state of existing Env constructs and ligand complexes used for high-resolution structures recently revealed that they correspond to the downstream conformations. The structure of the pretriggered Env conformation, preferentially recognized by broadly neutralizing antibodies, remains unknown. Here, we identify experimental conditions that stabilize membrane-bound and shedding-resistant virus Env trimers in state 1, potentially facilitating structural characterization of this unknown conformational state.


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