title: A triad of lys12, lys41, arg78 spatial domain, a novel identified heparin binding site on tat protein, facilitates tat-driven cell adhesion.
abstract: Tat protein, released by HIV-infected cells, has a battery of important biological effects leading to distinct AIDS-associated pathologies. Cell surface heparan sulfate protoglycans (HSPGs) have been accepted as endogenous Tat receptors, and the Tat basic domain has been identified as the heparin binding site. However, findings that deletion or substitution of the basic domain inhibits but does not completely eliminate Tat-heparin interactions suggest that the basic domain is not the sole Tat heparin binding site. In the current study, an approach integrating computational modeling, mutagenesis, biophysical and cell-based assays was used to elucidate a novel, high affinity heparin-binding site: a Lys12, Lys41, Arg78 (KKR) spatial domain. This domain was also found to facilitate Tat-driven β1 integrin activation, producing subsequent SLK cell adhesion in an HSPG-dependent manner, but was not involved in Tat internalization. The identification of this new heparin binding site may foster further insight into the nature of Tat-heparin interactions and subsequent biological functions, facilitating the rational design of new therapeutics against Tat-mediated pathological events.
authors.affiliation: Department of Pharmacology and Glycobiology, Marine Drug and Food Institute, Ocean University of China, Qingdao, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ai
authors.forename: Xianliang
authors.initials: X
authors.lastname: Xin
authors.forename: Mingyue
authors.initials: M
authors.lastname: Zheng
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.forename: Shuying
authors.initials: S
authors.lastname: Peng
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Limei
authors.initials: L
authors.lastname: Wang
authors.forename: Hualiang
authors.initials: H
authors.lastname: Jiang
authors.forename: Meiyu
authors.initials: M
authors.lastname: Geng
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000502:physiology*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D006493:Heparin / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006801:Humans; D039641:Integrin beta Chains / Q000378:metabolism; D062105:Molecular Docking Simulation; D016296:Mutagenesis; D017434:Protein Structure, Tertiary; D020349:Surface Plasmon Resonance; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D019812:Heparan Sulfate Proteoglycans; D039641:Integrin beta Chains; D054322:tat Gene Products, Human Immunodeficiency Virus; D006493:Heparin