Siarhei Kharytonchyk

Publications (2)35.2 Total impact

• Article: Identification of a minimal region of the HIV-1 5'-leader required for RNA dimerization, NC binding, and packaging.

  Xiao Heng, Siarhei Kharytonchyk, Eric L Garcia, Kun Lu, Sai Sachin Divakaruni, Courtney LaCotti, Kedy Edme, Alice Telesnitsky, Michael F Summers
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  ABSTRACT: Assembly of human immunodeficiency virus type 1 (HIV-1) particles is initiated in the cytoplasm by the formation of a ribonucleoprotein complex comprising the dimeric RNA genome and a small number of viral Gag polyproteins. Genomes are recognized by the nucleocapsid (NC) domains of Gag, which interact with packaging elements believed to be located primarily within the 5'-leader (5'-L) of the viral RNA. Recent studies revealed that the native 5'-L exists as an equilibrium of two conformers, one in which dimer-promoting residues and NC binding sites are sequestered and packaging is attenuated, and one in which these sites are exposed and packaging is promoted. To identify the elements within the dimeric 5'-L that are important for packaging, we generated HIV-1 5'-L RNAs containing mutations and deletions designed to eliminate substructures without perturbing the overall structure of the leader and examined effects of the mutations on RNA dimerization, NC binding, and packaging. Our findings identify a 159-residue RNA packaging signal that possesses dimerization and NC binding properties similar to those of the intact 5'-L and contains elements required for efficient RNA packaging.
  Journal of Molecular Biology 03/2012; 417(3):224-39. · 4.00 Impact Factor
• Article: NMR detection of structures in the HIV-1 5'-leader RNA that regulate genome packaging.

  Kun Lu, Xiao Heng, Lianko Garyu, Sarah Monti, Eric L Garcia, Siarhei Kharytonchyk, Bilguujin Dorjsuren, Gowry Kulandaivel, Simonne Jones, Atheeth Hiremath, Sai Sachin Divakaruni, Courtney LaCotti, Shawn Barton, Daniel Tummillo, Azra Hosic, Kedy Edme, Sara Albrecht, Alice Telesnitsky, Michael F Summers
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  ABSTRACT: The 5'-leader of the HIV-1 genome regulates multiple functions during viral replication via mechanisms that have yet to be established. We developed a nuclear magnetic resonance approach that enabled direct detection of structural elements within the intact leader (712-nucleotide dimer) that are critical for genome packaging. Residues spanning the gag start codon (AUG) form a hairpin in the monomeric leader and base pair with residues of the unique-5' region (U5) in the dimer. U5:AUG formation promotes dimerization by displacing and exposing a dimer-promoting hairpin and enhances binding by the nucleocapsid (NC) protein, which is the cognate domain of the viral Gag polyprotein that directs packaging. Our findings support a packaging mechanism in which translation, dimerization, NC binding, and packaging are regulated by a common RNA structural switch.
  Science 10/2011; 334(6053):242-5. · 31.20 Impact Factor