An alternate conformation and a third metal in PstP/Ppp, the M. tuberculosis PP2C-Family Ser/Thr protein phosphatase

Structure. 2004 Nov;12(11):1947-54. doi: 10.1016/j.str.2004.09.008.


Serine/threonine protein phosphatases are central mediators of phosphorylation-dependent signals in eukaryotes and a variety of pathogenic bacteria. Here, we report the crystal structure of the intracellular catalytic domain of Mycobacterium tuberculosis PstPpp, a membrane-anchored phosphatase in the PP2C family. Despite sharing the fold and two-metal center of human PP2Calpha, the PstPpp catalytic domain binds a third Mn(2+) in a site created by a large shift in a previously unrecognized flap subdomain adjacent to the active site. Mutations in this site selectively increased the Michaelis constant for Mn(2+) in the reaction of a noncognate, small-molecule substrate, p-nitrophenyl phosphate. The PstP/Ppp structure reveals core functional motifs that advance the framework for understanding the mechanisms of substrate recognition, catalysis, and regulation of PP2C phosphatases.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Catalytic Domain
  • Models, Molecular
  • Molecular Sequence Data
  • Mycobacterium tuberculosis / enzymology*
  • Phosphoprotein Phosphatases / chemistry*
  • Phosphoprotein Phosphatases / metabolism
  • Protein Conformation
  • Sequence Homology, Amino Acid
  • Substrate Specificity


  • Phosphoprotein Phosphatases

Associated data

  • PDB/1TX0