Crystal structure of X-prolyl aminopeptidase from Caenorhabditis elegans: a cytosolic enzyme with a di-nuclear active site

Shalini Iyer, Penelope J. La-Borde, Karl A P Payne, Mark R. Parsons, Anthony J. Turner, R. Elwyn Isaac, K. Ravi Acharya

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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.

Original languageEnglish
Pages (from-to)292-302
Number of pages11
JournalFEBS Open Bio
Issue number1
Publication statusPublished - Jan 2015


  • Apstatin
  • Di-nuclear active site
  • Protease inhibitor
  • X-prolyl aminopeptidase
  • X-ray crystallography
  • Zinc metalloprotease


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