Plasma membrane aquaporin AqpZ protein is essential for glucose metabolism during photomixotrophic growth of Synechocystis sp. PCC 6803

Masaro Akai, Kiyoshi Onai, Miyako Kusano, Mayuko Sato, Henning Redestig, Kiminori Toyooka, Megumi Morishita, Hiroshi Miyake, Akihiro Hazama, Vanessa Checchetto, Ildikò Szabò, Ken Matsuoka, Kazuki Saito, Masato Yasui, Masahiro Ishiura, Nobuyuki Uozumi

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


The genome of Synechocystis PCC 6803 contains a single gene encoding an aquaporin, aqpZ. The AqpZ protein functioned as a water-permeable channel in the plasma membrane. However, the physiological importance of AqpZ in Synechocystis remains unclear. We found that growth in glucose-containing medium inhibited proper division of ΔaqpZ cells and led to cell death. Deletion of a gene encoding a glucose transporter in the ΔaqpZ background alleviated the glucose-mediated growth inhibition of the ΔaqpZ cells. The ΔaqpZ cells swelled more than the wild type after the addition of glucose, suggesting an increase in cytosolic osmolarity. This was accompanied by a down-regulation of the pentose phosphate pathway and concurrent glycogen accumulation. Metabolite profiling by GC/TOF-MS of wild-type and ΔaqpZ cells revealed a relative decrease of intermediates of the tricarboxylic acid cycle and certain amino acids in the mutant. The changed levels of metabolites may have been the cause for the observed decrease in growth rate of the ΔaqpZ cells along with decreased PSII activity atpHvalues ranging from 7.5 to 8.5. A mutant in sll1961, encoding a putative transcription factor, and a Δhik31 mutant, lacking a putative glucose-sensing kinase, both exhibited higher glucose sensitivity than the ΔaqpZ cells. Examination of protein expression indicated that sll1961 functioned as a positive regulator of aqpZ gene expression but not as the only regulator. Overall, the ΔaqpZ cells showed defects in macronutrient metabolism, pH homeostasis, and cell division under photomixotrophic conditions, consistent with an essential role of AqpZ in glucose metabolism.

Original languageEnglish
Pages (from-to)25224-25235
Number of pages12
JournalJournal of Biological Chemistry
Issue number28
Publication statusPublished - 2011 Jul 15

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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