Novel Structural Mechanism of Allosteric Regulation of Aspartic Peptidases via an Evolutionarily Conserved Exosite

Iva Hánová, Jiří Brynda, Radka Houštecká, Nawsad Alam, Daniel Sojka, Petr Kopáček, Lucie Marešová, Jiří Vondrášek, Martin Horn, Ora Schueler-Furman, Michael Mareš*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Pepsin-family aspartic peptidases are biosynthesized as inactive zymogens in which the propeptide blocks the active site until its proteolytic removal upon enzyme activation. Here, we describe a novel dual regulatory function for the propeptide using a set of crystal structures of the parasite cathepsin D IrCD1. In the IrCD1 zymogen, intramolecular autoinhibition by the intact propeptide is mediated by an evolutionarily conserved exosite on the enzyme core. After activation, the mature enzyme employs the same exosite to rebind a small fragment derived from the cleaved propeptide. This fragment functions as an effective natural inhibitor of mature IrCD1 that operates in a pH-dependent manner through a unique allosteric inhibition mechanism. The study uncovers the propeptide-binding exosite as a target for the regulation of pepsin-family aspartic peptidases and defines the structural requirements for exosite inhibition. Aspartic peptidases (APs) are critically involved in numerous pathologies; however, little is known about their physiological regulation. Hánová et al. discovered the first selective endogenous inhibitor of APs in higher organisms. It is generated by autoproteolysis and acts through a unique structural mechanism.

Original languageAmerican English
Pages (from-to)318-329.e4
JournalCell Chemical Biology
Volume25
Issue number3
DOIs
StatePublished - 15 Mar 2018

Bibliographical note

Publisher Copyright:
© 2018 Elsevier Ltd

Keywords

  • allosteric inhibitor
  • aspartic peptidase
  • crystal structure
  • exosite
  • proteolysis

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