title: X-ray crystallographic structure of the angiogenesis inhibitor, angiostatin, bound to a peptide from the group A streptococcal surface protein PAM.
abstract: The crystal structure of the human Pg-derived angiogenesis inhibitor, angiostatin, complexed to VEK-30, a peptide from the group A streptococcal surface protein, PAM, was determined and refined to 2.3 A resolution. This is the first structure of angiostatin bound to a ligand and provides a model of the interaction between Pg and streptococcal-derived pathogenic proteins. VEK-30 contains a "through-space isostere" for C-terminal lysine, wherein Arg and Glu side chains, separated by one helical turn, bind within the bipolar angiostatin kringle 2 (K2) domain lysine-binding site. VEK-30 also makes several contacts with K2 residues that exist outside of the canonical LBS and are not conserved among the other Pg kringles, thus providing a molecular basis for the selectivity of VEK-30 for K2. The structure also shows that Pg kringle domains undergo significant structural rearrangement relative to one another and reveals dimerization between two molecules of angiostatin and VEK-30 related by crystallographic symmetry. This dimerization, which exists only in the crystal structure, is consistent with the parallel coiled-coil full-length PAM dimer expected from sequence similarities and homology modeling.
authors.affiliation: Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Cnudde
authors.forename: Mary
authors.initials: M
authors.lastname: Prorok
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Castellino
authors.forename: James H
authors.initials: JH
authors.lastname: Geiger
mesh_terms: D043168:Angiostatins / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; D043168:Angiostatins