DNA Accelerates the Inhibition of Human Cathepsin V by Serpins Academic Article uri icon

abstract

  • A balance between proteolytic activity and protease inhibition is crucial to the appropriate function of many biological processes. There is mounting evidence for the presence of both papain-like cysteine proteases and serpins with a corresponding inhibitory activity in the nucleus. Well characterized examples of cofactors fine tuning serpin activity in the extracellular milieu are known, but such modulation has not been studied for protease-serpin interactions within the cell. Accordingly, we present an investigation into the effect of a DNA-rich environment on the interaction between model serpins (MENT and SCCA-1), cysteine proteases (human cathepsin V and human cathepsin L), and cystatin A. DNA was indeed found to accelerate the rate at which MENT inhibited cathepsin V, a human orthologue of mammalian cathepsin L, up to 50-fold, but unexpectedly this effect was primarily effected via the protease and secondarily by the recruitment of the DNA as a "template" onto which cathepsin V and MENT are bound. Notably, the protease-mediated effect was found to correspond both with an altered substrate turnover and a conformational change within the protease. Consistent with this, cystatin inhibition, which relies on occlusion of the active site rather than the substrate-like behavior of serpins, was unaltered by DNA. This represents the first example of modulation of serpin inhibition of cysteine proteases by a co-factor and reveals a mechanism for differential regulation of cathepsin proteolytic activity in a DNA-rich environment.

authors

  • Ong, Poh Chee
  • McGowan, Sheena
  • Pearce, Mary C
  • Irving, James A
  • Kan, Wan-Ting
  • Grigoryev, Sergei A
  • Turk, Boris
  • Silverman, Gary A
  • Brix, Klaudia
  • Bottomley, Stephen P
  • Whisstock, James C
  • Pike, Robert N

publication date

  • December 21, 2007