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Activity of the mycobacterial proteasomal ATPase Mpa is reversibly regulated by pupylation

Cyrille L Delley1, Frank Striebel, Franziska M Heydenreich

  • 1Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland.

The Journal of Biological Chemistry
|January 3, 2012
PubMed

Insights

Pupylation, a bacterial protein modification, inactivates the Mpa enzyme in Mycobacterium tuberculosis. This reversible process allows controlled protein degradation via the proteasome.

Area of Science:

  • Microbiology
  • Biochemistry
  • Molecular Biology

Background:

  • Pupylation is a bacterial post-translational modification involving prokaryotic ubiquitin-like protein (Pup).
  • In Mycobacterium tuberculosis, the proteasome-interacting ATPase Mpa recognizes and degrades pupylated substrates.
  • Mpa itself is a target for pupylation, suggesting a regulatory mechanism.

Purpose of the Study:

  • To investigate the effect of Mpa pupylation on its function.
  • To elucidate the mechanism of Mpa inactivation and reactivation.
  • To understand the role of Pup ligase PafA and depupylase Dop in regulating Mpa activity.

Main Methods:

  • Investigating Mpa pupylation by PafA using biochemical assays.
  • Assessing the impact of Mpa pupylation on its interaction with the proteasome.
  • Analyzing the effect of depupylation by Dop on Mpa activity.
  • Studying the oligomeric state of Mpa under different conditions.

Main Results:

  • PafA predominantly produces monopupylated Mpa on a C-terminal lysine residue.
  • Pupylated Mpa is functionally inactive, unable to associate with the proteasome.
  • Mpa inactivation is accelerated by Pup- and ATPase-driven deoligomerization.
  • Mpa activity is chemically and functionally reversible upon depupylation by Dop.

Conclusions:

  • Mpa pupylation serves as a mechanism for reversible inactivation of the proteasome-interacting ATPase.
  • This reversible modification allows for precise control over Pup-mediated proteasomal degradation.
  • The interplay between PafA, Pup, and Dop provides a dynamic regulatory system for Mpa function.

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