Mechanism for HIV-1 Tat Insertion into the Endosome Membrane Export

@article{citeulike:5455710, abstract = {The human immunodeficiency virus, type 1, transactivating protein Tat is a small protein that is strictly required for viral transcription and multiplication within infected cells. The infected cells actively secrete Tat using an unconventional secretion pathway. Extracellular Tat can affect different cell types and induce severe cell dysfunctions ranging from cell activation to cell death. To elicit most cell responses, Tat needs to reach the cell cytosol. To this end, Tat is endocytosed, and low endosomal pH will then trigger Tat translocation to the cytosol. Although this translocation step is critical for Tat cytosolic delivery, how Tat could interact with the endosome membrane is unknown, and the key residues involved in this interaction require identification. We found that, upon acidification below pH 6.0 (i.e. within the endosomal pH range), Tat inserts into model membranes such as monolayers or lipid vesicles. This insertion process relies on Tat single Trp, Trp-11, which is not needed for transactivation and could be replaced by another aromatic residue for membrane insertion. Nevertheless, Trp-11 is strictly required for translocation. Tat conformational changes induced by low pH involve a sensor made of its first acidic residue (Glu/Asp-2) and the end of its basic domain (residues 55-57). Mutation of one of these elements results in membrane insertion above pH 6.5. Tat basic domain is also required for efficient Tat endocytosis and membrane insertion. Together with the strict conservation of Tat Trp among different virus isolates, our results point to an important role for Tat-membrane interaction in the multiplication of human immunodeficiency virus type 1. 10.1074/jbc.M109.023705}, author = {Yezid, Hocine and Konate, Karidia and Debaisieux, Solene and Bonhoure, Anne and Beaumelle, Bruno}, citeulike-article-id = {5455710}, citeulike-linkout-0 = {http://dx.doi.org/10.1074/jbc.M109.023705}, citeulike-linkout-1 = {http://www.jbc.org/cgi/content/abstract/284/34/22736}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/19549783}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=19549783}, day = {21}, doi = {10.1074/jbc.M109.023705}, journal = {J. Biol. Chem.}, keywords = {intertion, membrane, tat, transduction, tryptophan, yezid09pdf}, month = {August}, number = {34}, pages = {22736--22746}, posted-at = {2009-08-18 01:40:06}, priority = {2}, title = {Mechanism for HIV-1 Tat Insertion into the Endosome Membrane}, url = {http://dx.doi.org/10.1074/jbc.M109.023705}, volume = {284}, year = {2009} }

TY - JOUR ID - citeulike:5455710 L3 - citeulike-article-id:5455710 N2 - The human immunodeficiency virus, type 1, transactivating protein Tat is a small protein that is strictly required for viral transcription and multiplication within infected cells. The infected cells actively secrete Tat using an unconventional secretion pathway. Extracellular Tat can affect different cell types and induce severe cell dysfunctions ranging from cell activation to cell death. To elicit most cell responses, Tat needs to reach the cell cytosol. To this end, Tat is endocytosed, and low endosomal pH will then trigger Tat translocation to the cytosol. Although this translocation step is critical for Tat cytosolic delivery, how Tat could interact with the endosome membrane is unknown, and the key residues involved in this interaction require identification. We found that, upon acidification below pH 6.0 (i.e. within the endosomal pH range), Tat inserts into model membranes such as monolayers or lipid vesicles. This insertion process relies on Tat single Trp, Trp-11, which is not needed for transactivation and could be replaced by another aromatic residue for membrane insertion. Nevertheless, Trp-11 is strictly required for translocation. Tat conformational changes induced by low pH involve a sensor made of its first acidic residue (Glu/Asp-2) and the end of its basic domain (residues 55-57). Mutation of one of these elements results in membrane insertion above pH 6.5. Tat basic domain is also required for efficient Tat endocytosis and membrane insertion. Together with the strict conservation of Tat Trp among different virus isolates, our results point to an important role for Tat-membrane interaction in the multiplication of human immunodeficiency virus type 1. 10.1074/jbc.M109.023705 IS - 34 JF - J. Biol. Chem. EP - 22746 TI - Mechanism for HIV-1 Tat Insertion into the Endosome Membrane VL - 284 SP - 22736 KW - intertion KW - membrane KW - tat KW - transduction KW - tryptophan KW - yezid09pdf AU - Yezid, Hocine AU - Konate, Karidia AU - Debaisieux, Solene AU - Bonhoure, Anne AU - Beaumelle, Bruno PY - 2009/08/21/ UR - http://dx.doi.org/10.1074/jbc.M109.023705 ER -