Water and CO2 permeability of SsAqpZ, the cyanobacterium Synechococcus sp. PCC7942 aquaporin

Xiaodong Ding, Tadashi Matsumoto, Patrizia Gena, Chengwei Liu, Marialuisa Pellegrini-Calace, Shihua Zhong, Xiaoli Sun, Yanming Zhu, Maki Katsuhara, Ikuko Iwasaki, Yoshichika Kitagawa, Giuseppe Calamita

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Background information: Cyanobacteria possess Aquaporin-Z (AqpZ) membrane channels which have been suggested to mediate the water efflux underlying osmostress-inducible gene expression and to be essential for glucose metabolism under photomixotrophic growth. However, preliminary observations suggest that the biophy-sical properties of transport and physiological meaning of AqpZ in such photosynthetic microorganisms are not yet completely assessed. Results: In this study, we used Xenopus laevis oocyte and proteoliposome systems to directly demonstrate the water permeability of the cyanobacterium Synechococcus sp. PCC7942 aquaporin, SsAqpZ. By an in vitro assay of intracellular acidification in yeast cells, SsAqpZ was found to transport also CO2. Consistent with this result, during the entire exponential phase of growth, Synechococcus SsAqpZ-null-mutant cells grew slower than the corresponding wild-type cells. This phenotype was stronger with higher levels of extracellular CO2. In line with the conversion of CO2 gas into HCO3- ions under alkaline conditions, the impairment in growth of the SsAqpZ-null strain was weaker in more alkaline culture medium. Conclusions: Cyanobacterial SsAqpZ may exert a pleiotropic function in addition to the already reported roles in macronutrient homeostasis and osmotic-stress response as it appears to constitute an important pathway in CO2 uptake, a fundamental step in photosynthesis.

Original languageEnglish
Pages (from-to)118-128
Number of pages11
JournalBiology of the Cell
Issue number3
Publication statusPublished - Mar 1 2013


  • Aquaporin channels
  • CO
  • Cyanobacteria
  • Osmoregulation
  • Photosynthesis

ASJC Scopus subject areas

  • Cell Biology


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