title: Crystal structure of X-prolyl aminopeptidase from Caenorhabditis elegans: A cytosolic enzyme with a di-nuclear active site.
abstract: Eukaryotic aminopeptidase P1 (APP1), also known as X-prolyl aminopeptidase (XPNPEP1) in human tissues, is a cytosolic exopeptidase that preferentially removes amino acids from the N-terminus of peptides possessing a penultimate N-terminal proline residue. The enzyme has an important role in the catabolism of proline containing peptides since peptide bonds adjacent to the imino acid proline are resistant to cleavage by most peptidases. We show that recombinant and catalytically active Caenorhabditis elegans APP-1 is a dimer that uses dinuclear zinc at the active site and, for the first time, we provide structural information for a eukaryotic APP-1 in complex with the inhibitor, apstatin. Our analysis reveals that C. elegans APP-1 shares similar mode of substrate binding and a common catalytic mechanism with other known X-prolyl aminopeptidases.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Shalini
authors.initials: S
authors.lastname: Iyer
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK ; School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Penelope J
authors.initials: PJ
authors.lastname: La-Borde
authors.affiliation: Faculty of Biological Sciences, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK ; Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, UK.
authors.forename: Karl A P
authors.initials: KA
authors.lastname: Payne
authors.affiliation: Faculty of Biological Sciences, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK ; Sevenoaks School, Sevenoaks TN13 1HU, UK.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Parsons
authors.affiliation: Faculty of Biological Sciences, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Turner
authors.affiliation: Faculty of Biological Sciences, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: R Elwyn
authors.initials: RE
authors.lastname: Isaac
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: K Ravi
authors.initials: KR
authors.lastname: Acharya
keywords: APP1, aminopeptidase P1; Apstatin; CCP4, computational collaborative project 4; Di-nuclear active site; ICP-AES, inductively coupled plasma atomic emission spectroscopy; ICP-MS, inductively coupled plasma mass spectrometry; MAP, methionine aminopeptidase; NMR, nuclear magnetic resonance; PCR, polymerase chain reaction; PEG3350, polyethylene glycol 3350; Protease inhibitor; X-prolyl aminopeptidase; X-ray crystallography; XPNPEP, X-prolyl aminopeptidase; Zinc metalloprotease; rmsd, root mean square deviation