title: Effect of the redox state on HIV-1 tat protein multimerization and cell internalization and trafficking.
abstract: The redox state of the cysteine-rich region of the HIV Tat protein is known to play a crucial role in Tat biological activity. In this article, we show that Tat displays two alternative functional states depending on the presence of either one or three reduced sulphydryl groups in the cysteine-rich region, respectively. Using different approaches, a disulfide pattern has been defined for the Tat protein and a specific DTT-dependent breaking order of disulfide bonds highlighted. The Tat redox state deeply influences macrophage protein uptake. Immunoistochemistry analysis shows that the oxidized protein does not enter cells, whereas partially reduced protein reaches the cytosol and, to a limited extent, the nucleus. Finally electrophoretic analysis shows Tat high-molecular weight multi-aggregation, resulting in the loss of biological activity. This is due to strong electrostatic and metal-binding interactions, whereas Tat dimerization involves metal-binding interactions as well as disulfide bond formation.
authors: Department of Molecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, 61029, Urbino, Italy.
authors: Raffaella
authors: R
authors: Pierleoni
authors: Michele
authors: M
authors: Menotta
authors: Antonella
authors: A
authors: Antonelli
authors: Carla
authors: C
authors: Sfara
authors: Giordano
authors: G
authors: Serafini
authors: Sabrina
authors: S
authors: Dominici
authors: Maria Elena
authors: ME
authors: Laguardia
authors: Annalisa
authors: A
authors: Salis
authors: Gianluca
authors: G
authors: Damonte
authors: Lucia
authors: L
authors: Banci
authors: Marco
authors: M
authors: Porcu
authors: Paolo
authors: P
authors: Monini
authors: Barbara
authors: B
authors: Ensoli
authors: Mauro
authors: M
authors: Magnani
mesh_terms: D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides; D004705:Endocytosis; D015696:Gene Products, tat / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics*; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D013058:Mass Spectrometry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D055503:Protein Multimerization; D021381:Protein Transport
chemical_list: D004220:Disulfides; D015696:Gene Products, tat; D003545:Cysteine