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

J Biol Chem. 2012 Mar 9;287(11):7907-14. doi: 10.1074/jbc.M111.331124. Epub 2011 Dec 30.


Pupylation is a bacterial post-translational modification of target proteins on lysine residues with prokaryotic ubiquitin-like protein Pup. Pup-tagged substrates are recognized by a proteasome-interacting ATPase termed Mpa in Mycobacterium tuberculosis. Mpa unfolds pupylated substrates and threads them into the proteasome core particle for degradation. Interestingly, Mpa itself is also a pupylation target. Here, we show that the Pup ligase PafA predominantly produces monopupylated Mpa modified homogeneously on a single lysine residue within its C-terminal region. We demonstrate that this modification renders Mpa functionally inactive. Pupylated Mpa can no longer support Pup-mediated proteasomal degradation due to its inability to associate with the proteasome core. Mpa is further inactivated by rapid Pup- and ATPase-driven deoligomerization of the hexameric Mpa ring. We show that pupylation of Mpa is chemically and functionally reversible. Mpa regains its enzymatic activity upon depupylation by the depupylase Dop, affording a rapid and reversible activity control over Mpa function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Amidohydrolases / genetics
  • Amidohydrolases / metabolism
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Mycobacterium tuberculosis / enzymology*
  • Mycobacterium tuberculosis / genetics
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Folding
  • Protein Processing, Post-Translational / physiology*
  • Proteolysis*
  • Ubiquitins / genetics
  • Ubiquitins / metabolism*
  • Virulence Factors / genetics
  • Virulence Factors / metabolism


  • Bacterial Proteins
  • Pup protein, Mycobacterium tuberculosis
  • Ubiquitins
  • Virulence Factors
  • Proteasome Endopeptidase Complex
  • Amidohydrolases
  • Dop protein, Mycobacterium tuberculosis
  • Adenosine Triphosphatases