Amiloride and harmaline are potent inhibitors of NhaB a Na+/H+ antiporter from Escherichia coli

Elhanan Pinner, Etana Padan, Shimon Schuldiner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The diuretic drug amiloride is a specific inhibitor of sodium transporting proteins in several cell types. Attempts to inhibit this activity in membrane vesicles derived from various bacteria, did not yield clear results. Therefore, we tested the effect of amiloride and its derivatives on the purified Na+/H+ antiporters of E. coli reconstituted in functional form in proteoliposomes. Whereas NhaA is not inhibited by amiloride, both amiloride and harmaline are potent inhibitors of NhaB with K0.5 of 6 and 15 μM, respectively. The pattern of inhibition by amiloride derivatives is different from that reported for mammalian antiporters but similar to that reported for the Na+/H+ antiporter of D. salia [Katz, A., Kleyman, T.R. and Pick, U. (1994) Biochemistry 33, 2389-2393]. Clonidine is a poor inhibitor (K0.5 = 200 μM) while cimetidine had no effect on the antiporter up to concentration of 1 mM. These new potent inhibitors provide us with important tools for the study of the mechanism of action of NhaB.

Original languageEnglish
Pages (from-to)18-22
Number of pages5
JournalFEBS Letters
Volume365
Issue number1
DOIs
StatePublished - 22 May 1995

Keywords

  • Membrane protein
  • Proteoliposome
  • Reconstitution
  • Salinity
  • Transport

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