A high-conductance mode of a poly-3-hydroxybutyrate/calcium/polyphosphate channel isolated from competent Escherichia coli cells

Evgeny Pavlov, Chelsey Grimbly, Catherine T.M. Diao, Robert J. French

Research output: Contribution to journalArticlepeer-review

Abstract

Reconstitution into planar lipid bilayers of a poly-3-hydroxybutyrate/ calcium/polyphosphate (PHB/Ca2+/polyP) complex from Escherichia coli membranes yields cationic-selective, 100 pS channels (Das, S., Lengweiler, U.D., Seebach, D. and Reusch, R.N. (1997) Proof for a non-proteinaceous calcium-selective channel in Escherichia coli by total synthesis from (R)-3-hydroxybutanoic acid and inorganic polyphosphate. Proc. Natl. Acad. Sci. USA 94, 9075-9079). Here, we report that this complex can also form larger, weakly selective pores, with a maximal conductance ranging from 250 pS to 1 nS in different experiments (symmetric 150 mM KCl). Single channels were inhibited by lanthanum (IC50 = 42 ± 4 μM, means ± S.E.M.) with an unusually high Hill coefficient (8.4 ± 1.2). Transition to low-conductance states (<250 pS) was favored by increased membrane polarization (|V| ≥ 50 mV). High conductance states (>250 pS) may reflect conformations important for genetic transformability, or "competence", of the bacterial cells, which requires the presence of the PHB/Ca 2+/polyP complex in the membrane.

Original languageEnglish (US)
Pages (from-to)5187-5192
Number of pages6
JournalFEBS Letters
Volume579
Issue number23
DOIs
StatePublished - Sep 26 2005

Keywords

  • Escherichia coli
  • Planar lipid bilayers
  • Polyphosphate
  • Reconstitution

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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