Pyrophosphate inhibition of rho ATPase: a mechanism of coupling to RNA polymerase activity

Proc Natl Acad Sci U S A. 1982 Jul;79(13):3992-6. doi: 10.1073/pnas.79.13.3992.

Abstract

The effects of pyrophosphate on RNA binding and ATPase activities of Escherichia coli transcription termination factor rho have been studied. Mutant rho-115 protein has a temperature-sensitive RNA-dependent ATPase activity due to the thermolability of binding to RNA [Kent, R.B. & Guterman, S.K. (1981) Fed. Proc. Fed. Am. Soc. Exp. Biol. 40, 1765 (abstr.)]. The presence of either ATP or pyrophosphate at comparable concentrations stabilizes the binary complex of rho and poly(C) at high temperature. ADP at 8-fold greater concentration also stabilizes the mutant rho-RNA binary complex. Pyrophosphate is a noncompetitive inhibitor (Ki = 0.07 mM) of rho poly(C)-dependent ATPase, an activity that is required for rho-mediated termination. These results suggest the existence of a regulatory site on the rho molecule. We suggest that rho NTPase is regulated by RNA polymerase (EC 2.7.7.6) so that during transcription elongation the RNA polymerase competes successfully with rho for substrates and inhibits rho NTPase with product pyrophosphate. Further, RNA polymerase pausing may result in reduced pyrophosphate and increased NTP concentrations, allowing rho NTPase to function.

Publication types

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

MeSH terms

  • Adenosine Triphosphatases / antagonists & inhibitors*
  • DNA-Directed RNA Polymerases / metabolism*
  • Diphosphates / pharmacology*
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Kinetics
  • Poly C
  • Rho Factor / metabolism
  • Transcription, Genetic*

Substances

  • Diphosphates
  • Rho Factor
  • Poly C
  • DNA-Directed RNA Polymerases
  • Adenosine Triphosphatases
  • rho-ATPase