Visualization of AqpZ-mediated water permeability in Escherichia coli by cryoelectron microscopy

Christian Delamarche, Daniel Thomas, Jean Paul Rolland, Alexandrine Froger, Jean Gouranton, Maria Svelto, Peter Agre, Giuseppe Calamita

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Transport of water across the plasma membrane is a fundamental process occurring in all living organisms. In bacteria, osmotic movement of water across the cytoplasmic membrane is needed to maintain cellular turgor; however, the molecular mechanisms of this process are poorly defined. Involvement of aquaporin water channels in bacterial water permeability was suggested by the recent discovery of the aquaporin gene, aqpZ, in Escherichia coli. By employing cryoelectron microscopy to compare E. coli cells containing (AqpZ+) and lacking (AqpZ-) aquaporin, we show that the AqpZ water channel rapidly mediates large water fluxes in response to sudden changes in extracellular osmolarity. These findings (i) demonstrate for the first time functional expression of a prokaryotic water channel, (ii) evidence the bidirectional water channel feature of AqpZ, (iii) document a role for AqpZ in bacterial osmoregulation, and (iv) define a suitable model for studying the physiology of prokaryotic water transport.

Original languageEnglish (US)
Pages (from-to)4193-4197
Number of pages5
JournalJournal of bacteriology
Issue number14
StatePublished - Jul 1999

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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