title: Structural basis for antagonism by suramin of heparin binding to vaccinia complement protein.
abstract: Suramin is a competitive inhibitor of heparin binding to many proteins, including viral envelope proteins, protein tyrosine phosphatases, and fibroblast growth factors (FGFs). It has been clinically evaluated as a potential therapeutic in treatment of cancers caused by unregulated angiogenesis, triggered by FGFs. Although it has shown clinical promise in treatment of several cancers, suramin has many undesirable side effects. There is currently no experimental structure that reveals the molecular interactions responsible for suramin inhibition of heparin binding, which could be of potential use in structure-assisted design of improved analogues of suramin. We report the structure of suramin, in complex with the heparin-binding site of vaccinia virus complement control protein (VCP), which interacts with heparin in a geometrically similar manner to many FGFs. The larger than anticipated flexibility of suramin manifested in this structure, and other details of VCP-suramin interactions, might provide useful structural information for interpreting interactions of suramin with many proteins.
authors.affiliation: Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, Alabama 35294-4400, USA.
authors.forename: Vannakambadi K
authors.initials: VK
authors.lastname: Ganesh
authors.forename: Suresh Kumar
authors.initials: SK
authors.lastname: Muthuvel
authors.forename: Scott A
authors.initials: SA
authors.lastname: Smith
authors.forename: Girish J
authors.initials: GJ
authors.lastname: Kotwal
authors.forename: Krishna H M
authors.initials: KH
authors.lastname: Murthy
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D006494:Heparin Antagonists / Q000737:chemistry*; D015394:Molecular Structure; D011485:Protein Binding / Q000187:drug effects; D013498:Suramin / Q000737:chemistry* / Q000494:pharmacology; D014616:Vaccinia virus / Q000737:chemistry*; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D006494:Heparin Antagonists; D014764:Viral Proteins; C066459:complement-control protein, Vaccinia virus; D013498:Suramin