Abstract
BackgroundBST-2 (bone marrow stromal cell antigen 2) is an interferon-inducible protein that inhibits virus release by tethering viral particles to the cell surface. This antiviral activity of BST-2 is antagonized by HIV-1 accessory protein Vpu. Vpu physically interacts with BST-2 through their mutual transmembrane (TM) domains. In this study, we utilized the BRET assay and molecular dynamics (MD) simulation method to further characterize the interaction of BST-2 and Vpu.ResultsAmino acids I34, L37, P40 and L41 in the TM domain of BST-2, and L11, A18 and W22 in the TM domain of Vpu were identified to be critical for the interaction between BST-2 and Vpu. The residues P40 in the TM domain of BST-2 and L11 in the TM domain of Vpu were shown, for the first time, to be important for their interaction. Furthermore, triple-amino-acid substitutions, 14–16 (AII to VAA) and 26–28 (IIE to AAA) in Vpu TM, not the single-residue mutation, profoundly disrupted BST-2/Vpu interaction. The results of MD simulation revealed significant conformational changes of the BST-2/Vpu complex as a result of mutating P40 of BST-2 and L11, 14–16 (AII to VAA) and 26–28 (IIE to AAA) of Vpu. In addition, disrupting the interaction between BST-2 and Vpu rendered BST-2 resistant to Vpu antagonization.ConclusionsThrough use of the BRET assay, we identified novel key residues P40 in the TM domain of BST-2 and L11 in the TM domain of Vpu that are important for their interaction. These results add new insights into the molecular mechanism behind BST-2 antagonization by HIV-1 Vpu.
Highlights
BST-2 is an interferon-inducible protein that inhibits virus release by tethering viral particles to the cell surface
Rluc or EYFP was fused with human BST-2 or human immunodeficiency virus type 1 (HIV-1) viral protein U (Vpu), respectively
In order to rule out the effect of BST-2 degradation by Vpu, the S52, 56A mutation of Vpu was used in the Bioluminescence resonance energy transfer (BRET) study (Figure 1a)
Summary
BST-2 (bone marrow stromal cell antigen 2) is an interferon-inducible protein that inhibits virus release by tethering viral particles to the cell surface. This antiviral activity of BST-2 is antagonized by HIV-1 accessory protein Vpu. Vpu physically interacts with BST-2 through their mutual transmembrane (TM) domains. We utilized the BRET assay and molecular dynamics (MD) simulation method to further characterize the interaction of BST-2 and Vpu. The bone marrow stromal antigen 2 (BST-2, referred to as Tetherin, CD317 or HM1.24) blocks the release of human immunodeficiency virus type 1 (HIV-1) by directly tethering viral particles to the membrane of infected cells [1,2]. Studies have revealed that mutation in the transmembrane of either BST-2 (L22, L23, G25, I26, V30, I33, I34, I36, L37, L41, and T45) or Vpu (A14, A18 and W22) renders BST-2 resistant to Vpu [16,23,24,25]
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