Structure-based design and development of functionalized Mercaptoguanine derivatives as inhibitors of the folate biosynthesis pathway enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Staphylococcus aureus

J Med Chem. 2014 Nov 26;57(22):9612-26. doi: 10.1021/jm501417f. Epub 2014 Nov 12.


6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), an enzyme from the folate biosynthesis pathway, catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin and is a yet-to-be-drugged antimicrobial target. Building on our previous discovery that 8-mercaptoguanine (8MG) is an inhibitor of Staphylococcus aureus HPPK (SaHPPK), we have identified and characterized the binding of an S8-functionalized derivative (3). X-ray structures of both the SaHPPK/3/cofactor analogue ternary and the SaHPPK/cofactor analogue binary complexes have provided insight into cofactor recognition and key residues that move over 30 Å upon binding of 3, whereas NMR measurements reveal a partially plastic ternary complex active site. Synthesis and binding analysis of a set of analogues of 3 have identified an advanced new lead compound (11) displaying >20-fold higher affinity for SaHPPK than 8MG. A number of these exhibited low micromolar affinity for dihydropteroate synthase (DHPS), the adjacent, downstream enzyme to HPPK, and may thus represent promising new leads to bienzyme inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / chemistry
  • Catalysis
  • Catalytic Domain
  • Crystallography, X-Ray
  • Dihydropteroate Synthase / chemistry
  • Diphosphotransferases / antagonists & inhibitors*
  • Diphosphotransferases / chemistry*
  • Folic Acid / biosynthesis*
  • Guanine / chemistry*
  • Ions
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Protein Binding
  • Protein Conformation
  • Pterins / chemistry
  • Staphylococcus aureus / enzymology*
  • Structure-Activity Relationship
  • Surface Plasmon Resonance


  • 6-hydroxymethyl-7,8-dihydropterin
  • Ions
  • Pterins
  • Guanine
  • Adenosine Triphosphate
  • Folic Acid
  • Dihydropteroate Synthase
  • Diphosphotransferases
  • 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase