title: Heparin binds to Leishmania donovani promastigotes and inhibits protein phosphorylation.
abstract: We show that promastigotes of Leishmania donovani, the causative agent of visceral leishmaniasis (kala-azar), possess heparin receptors on their surface. From a linear Scatchard plot of the binding data obtained using [3H]heparin and viable promastigotes, one derives a binding constant of 4.7 x 10(-7) M and an estimate of 860,000 receptors per parasite. The [3H]heparin bound to parasites could not be displaced by hyaluronic acid or by three other glycosaminoglycans (dermatan sulphate, chondroitin 4-sulphate and chondroitin 6-sulphate). It was demonstrated that exponential phase promastigotes growing in medium 199 supplemented with fetal bovine serum incorporate 35SO4 into a cell-associated macromolecule that has the properties of heparin proteoglycan. Heparin inhibits the activity of the cell-surface histone-protein kinase; incubation of viable promastigotes with [gamma-32P]ATP and MgCl2 (10 mM) in the absence and presence of heparin (0.01-0.5 mg/ml) for 10 min, followed by analysis by SDS/polyacrylamide-gel electrophoresis and autoradiography, revealed that the phosphorylation of 12 or 13 parasite proteins was inhibited by the glycosaminoglycan. These data suggest that heparin may play a role in the host-parasite relationship.
authors.affiliation: Department of Microbiology, Biochemistry and Molecular Biology, School of Medicine, University of Pittsburgh, PA 15261.
authors.forename: N K
authors.initials: NK
authors.lastname: Mukhopadhyay
authors.forename: K
authors.initials: K
authors.lastname: Shome
authors.forename: A K
authors.initials: AK
authors.lastname: Saha
authors.forename: J R
authors.initials: JR
authors.lastname: Hassell
authors.forename: R H
authors.initials: RH
authors.lastname: Glew
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002845:Chromatography; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017886:Durapatite; D006493:Heparin / Q000378:metabolism* / Q000494:pharmacology; D006882:Hydroxyapatites; D007700:Kinetics; D007893:Leishmania donovani / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D010750:Phosphoproteins / Q000302:isolation & purification; D010766:Phosphorylation; D006656:Protamine Kinase / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism* / Q000502:physiology
chemical_list: D006882:Hydroxyapatites; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011956:Receptors, Cell Surface; C037680:heparin receptor; D006493:Heparin; D017886:Durapatite; D011494:Protein Kinases; D006656:Protamine Kinase