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HIV Gag mimics the Tsg101-recruiting activity of the human Hrs protein.

Pornillos O, Higginson DS, Stray KM, Fisher RD, Garrus JE, Payne M, He GP, Wang HE, Morham SG, Sundquist WI - J. Cell Biol. (2003)

Bottom Line: Importantly, Hrs222-777 can recruit Tsg101 and rescue the budding of virus-like Gag particles that are missing native late domains.These observations indicate that Hrs normally functions to recruit Tsg101 to the endosomal membrane.HIV-1 Gag apparently mimics this Hrs activity, and thereby usurps Tsg101 and other components of the MVB vesicle fission machinery to facilitate viral budding.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Utah, School of Medicine, Salt Lake City, UT 84132, USA. wes@biochem.utah.edu

ABSTRACT
The HIV-1 Gag protein recruits the cellular factor Tsg101 to facilitate the final stages of virus budding. A conserved P(S/T)AP tetrapeptide motif within Gag (the "late domain") binds directly to the NH2-terminal ubiquitin E2 variant (UEV) domain of Tsg101. In the cell, Tsg101 is required for biogenesis of vesicles that bud into the lumen of late endosomal compartments called multivesicular bodies (MVBs). However, the mechanism by which Tsg101 is recruited from the cytoplasm onto the endosomal membrane has not been known. Now, we report that Tsg101 binds the COOH-terminal region of the endosomal protein hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs; residues 222-777). This interaction is mediated, in part, by binding of the Tsg101 UEV domain to the Hrs 348PSAP351 motif. Importantly, Hrs222-777 can recruit Tsg101 and rescue the budding of virus-like Gag particles that are missing native late domains. These observations indicate that Hrs normally functions to recruit Tsg101 to the endosomal membrane. HIV-1 Gag apparently mimics this Hrs activity, and thereby usurps Tsg101 and other components of the MVB vesicle fission machinery to facilitate viral budding.

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Domain organization of the HIV-1 Gag and human Tsg101 and Hrs proteins. The HIV Gag and Hrs proteins are aligned to emphasize their similarities, with the NH2-terminal membrane-binding domains separated from the COOH-terminal protein–protein interaction domains by a vertical dashed line. UEV, ubiquitin E2 variant; PRD, proline-rich domain; COIL, putative coiled-coil; SBOX, “steadiness box/Vps28 binding site” (Feng et al., 2000). Locations of P(S/T)AP and PPEY motifs are also indicated.
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fig1: Domain organization of the HIV-1 Gag and human Tsg101 and Hrs proteins. The HIV Gag and Hrs proteins are aligned to emphasize their similarities, with the NH2-terminal membrane-binding domains separated from the COOH-terminal protein–protein interaction domains by a vertical dashed line. UEV, ubiquitin E2 variant; PRD, proline-rich domain; COIL, putative coiled-coil; SBOX, “steadiness box/Vps28 binding site” (Feng et al., 2000). Locations of P(S/T)AP and PPEY motifs are also indicated.

Mentions: The HIV Gag protein orchestrates viral assembly and budding, and forms the structural shell of the immature virus (for review see Göttlinger, 2001). Even in the absence of any other viral proteins, HIV-1 Gag can form extracellular virus-like particles (VLPs) that resemble authentic HIV virions. Efficient release of HIV-1 virions and Gag VLPs from most cell types requires the presence of a “late domain” located in the COOH-terminal Gag p6 region (Göttlinger et al., 1991; Huang et al., 1995; Demirov et al., 2002b). All HIV-1 strains contain the late domain tetrapeptide motif P(S/T)AP (where the second position can be either Ser or Thr; Fig. 1), which is a docking site for the cellular protein, tumor susceptibility gene 101 (Tsg101; for review see Pornillos et al., 2002c). Tsg101 appears to facilitate viral budding by recruiting additional cellular factors that can catalyze release of the enveloped virion. In addition to the P(S/T)AP sequence found in HIV-1 Gag, distinct late domain sequences have also been identified and characterized in several other enveloped RNA viruses. The best characterized of these is the PPXY motif (where X is any amino acid), which binds the Nedd4 protein family of ubiquitin E3 ligases (Xiang et al., 1996; Harty et al., 1999, 2001; Strack et al., 2000; Kikonyogo et al., 2001; Yasuda et al., 2002; Timmins et al., 2003).


HIV Gag mimics the Tsg101-recruiting activity of the human Hrs protein.

Pornillos O, Higginson DS, Stray KM, Fisher RD, Garrus JE, Payne M, He GP, Wang HE, Morham SG, Sundquist WI - J. Cell Biol. (2003)

Domain organization of the HIV-1 Gag and human Tsg101 and Hrs proteins. The HIV Gag and Hrs proteins are aligned to emphasize their similarities, with the NH2-terminal membrane-binding domains separated from the COOH-terminal protein–protein interaction domains by a vertical dashed line. UEV, ubiquitin E2 variant; PRD, proline-rich domain; COIL, putative coiled-coil; SBOX, “steadiness box/Vps28 binding site” (Feng et al., 2000). Locations of P(S/T)AP and PPEY motifs are also indicated.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172688&req=5

fig1: Domain organization of the HIV-1 Gag and human Tsg101 and Hrs proteins. The HIV Gag and Hrs proteins are aligned to emphasize their similarities, with the NH2-terminal membrane-binding domains separated from the COOH-terminal protein–protein interaction domains by a vertical dashed line. UEV, ubiquitin E2 variant; PRD, proline-rich domain; COIL, putative coiled-coil; SBOX, “steadiness box/Vps28 binding site” (Feng et al., 2000). Locations of P(S/T)AP and PPEY motifs are also indicated.
Mentions: The HIV Gag protein orchestrates viral assembly and budding, and forms the structural shell of the immature virus (for review see Göttlinger, 2001). Even in the absence of any other viral proteins, HIV-1 Gag can form extracellular virus-like particles (VLPs) that resemble authentic HIV virions. Efficient release of HIV-1 virions and Gag VLPs from most cell types requires the presence of a “late domain” located in the COOH-terminal Gag p6 region (Göttlinger et al., 1991; Huang et al., 1995; Demirov et al., 2002b). All HIV-1 strains contain the late domain tetrapeptide motif P(S/T)AP (where the second position can be either Ser or Thr; Fig. 1), which is a docking site for the cellular protein, tumor susceptibility gene 101 (Tsg101; for review see Pornillos et al., 2002c). Tsg101 appears to facilitate viral budding by recruiting additional cellular factors that can catalyze release of the enveloped virion. In addition to the P(S/T)AP sequence found in HIV-1 Gag, distinct late domain sequences have also been identified and characterized in several other enveloped RNA viruses. The best characterized of these is the PPXY motif (where X is any amino acid), which binds the Nedd4 protein family of ubiquitin E3 ligases (Xiang et al., 1996; Harty et al., 1999, 2001; Strack et al., 2000; Kikonyogo et al., 2001; Yasuda et al., 2002; Timmins et al., 2003).

Bottom Line: Importantly, Hrs222-777 can recruit Tsg101 and rescue the budding of virus-like Gag particles that are missing native late domains.These observations indicate that Hrs normally functions to recruit Tsg101 to the endosomal membrane.HIV-1 Gag apparently mimics this Hrs activity, and thereby usurps Tsg101 and other components of the MVB vesicle fission machinery to facilitate viral budding.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Utah, School of Medicine, Salt Lake City, UT 84132, USA. wes@biochem.utah.edu

ABSTRACT
The HIV-1 Gag protein recruits the cellular factor Tsg101 to facilitate the final stages of virus budding. A conserved P(S/T)AP tetrapeptide motif within Gag (the "late domain") binds directly to the NH2-terminal ubiquitin E2 variant (UEV) domain of Tsg101. In the cell, Tsg101 is required for biogenesis of vesicles that bud into the lumen of late endosomal compartments called multivesicular bodies (MVBs). However, the mechanism by which Tsg101 is recruited from the cytoplasm onto the endosomal membrane has not been known. Now, we report that Tsg101 binds the COOH-terminal region of the endosomal protein hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs; residues 222-777). This interaction is mediated, in part, by binding of the Tsg101 UEV domain to the Hrs 348PSAP351 motif. Importantly, Hrs222-777 can recruit Tsg101 and rescue the budding of virus-like Gag particles that are missing native late domains. These observations indicate that Hrs normally functions to recruit Tsg101 to the endosomal membrane. HIV-1 Gag apparently mimics this Hrs activity, and thereby usurps Tsg101 and other components of the MVB vesicle fission machinery to facilitate viral budding.

Show MeSH
Related in: MedlinePlus