Dual inhibition of DNA polymerase PolC and protein tyrosine phosphatase CpsB uncovers a novel antibiotic target

Biochem Biophys Res Commun. 2013 Jan 4;430(1):167-72. doi: 10.1016/j.bbrc.2012.11.049. Epub 2012 Nov 27.


Increasing antibiotic resistance is making the identification of novel antimicrobial targets critical. Recently, we discovered an inhibitor of protein tyrosine phosphatase CpsB, fascioquinol E (FQE), which unexpectedly inhibited the growth of Gram-positive pathogens. CpsB is a member of the polymerase and histidinol phosphate phosphatase (PHP) domain family. Another member of this family found in a variety of Gram-positive pathogens is DNA polymerase PolC. We purified the PHP domain from PolC (PolC(PHP)), and showed that this competes away FQE inhibition of CpsB phosphatase activity. Furthermore, we showed that this domain hydrolyses the 5'-p-nitrophenyl ester of thymidine-5'-monophosphate (pNP-TMP), which has been used as a measure of exonuclease activity. Finally, we showed that FQE not only inhibits the phosphatase activity of CpsB, but also ability of PolC(PHP) to catalyse the hydrolysis of pNP-TMP. This suggests that PolC may be the essential target of FQE, and that the PHP domain may represent an as yet untapped target for the development of novel antibiotics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / antagonists & inhibitors*
  • Bacterial Proteins / chemistry
  • DNA-Directed DNA Polymerase / chemistry
  • Diterpenes / pharmacology*
  • Hydrolysis
  • Molecular Sequence Data
  • Nucleic Acid Synthesis Inhibitors*
  • Protein Structure, Tertiary
  • Protein Tyrosine Phosphatases / antagonists & inhibitors*
  • Protein Tyrosine Phosphatases / chemistry
  • Streptococcus pneumoniae / drug effects*
  • Streptococcus pneumoniae / enzymology
  • Sulfuric Acid Esters / pharmacology*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Diterpenes
  • Nucleic Acid Synthesis Inhibitors
  • Sulfuric Acid Esters
  • fascioquinol E
  • PolC protein, bacteria
  • DNA-Directed DNA Polymerase
  • CpsB protein, Streptococcus pneumoniae
  • Protein Tyrosine Phosphatases