title: Structure of Escherichia coli aminopeptidase P in complex with the inhibitor apstatin.
abstract: Aminopeptidase P (APPro) is a metalloprotease whose active site includes a dinuclear manganese(II) cluster. The enzyme cleaves the N-terminal residue from a polypeptide when the second residue is proline. A complex of Escherichia coli APPro (EcAPPro) with an inhibitor, apstatin [N-(2S,3R)-3-amino-2-hydroxy-4-phenyl-butanoyl-L-prolyl-L-prolyl-L-alaninamide], has been crystallized. Apstatin binds to the active site of EcAPPro with its N-terminal amino group coordinated to one of the two Mn(II) atoms at the metal centre. The apstatin hydroxyl group replaces a hydroxide ion which bridges the two metal atoms in the native enzyme. The first proline residue of apstatin lies in a small hydrophobic cleft. The structure of the apstatin-EcAPPro complex has been refined at 2.3 A resolution with residuals R = 0.179 and R(free) = 0.204. The structure of the complex illustrates how apstatin inhibits APPro and suggests how substrates may bind to the enzyme, but the basis of the proline-specificity remains elusive.
authors.affiliation: School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Graham
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Maher
authors.forename: William H
authors.initials: WH
authors.lastname: Simmons
authors.forename: Hans C
authors.initials: HC
authors.lastname: Freeman
authors.forename: J Mitchell
authors.initials: JM
authors.lastname: Guss
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D006878:Hydroxides / Q000737:chemistry; D007477:Ions; D008345:Manganese / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D012984:Software
chemical_list: D006878:Hydroxides; D007477:Ions; D010455:Peptides; D008345:Manganese; D011392:Proline; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase; C097277:apstatin