論文

査読有り 国際誌
2015年2月15日

Comparative analysis of kdp and ktr mutants reveals distinct roles of the potassium transporters in the model cyanobacterium Synechocystis sp. strain PCC 6803.

Journal of Bacteriology
  • Kei Nanatani
  • ,
  • Toshiaki Shijuku
  • ,
  • Yousuke Takano
  • ,
  • Lalu Zulkifli
  • ,
  • Tomoko Yamazaki
  • ,
  • Akira Tominaga
  • ,
  • Satoshi Souma
  • ,
  • Kiyoshi Onai
  • ,
  • Megumi Morishita
  • ,
  • Masahiro Ishiura
  • ,
  • Martin Hagemann
  • ,
  • Iwane Suzuki
  • ,
  • Hisataka Maruyama
  • ,
  • Fumihito Arai
  • ,
  • Nobuyuki Uozumi

197
4
開始ページ
676
終了ページ
87
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1128/JB.02276-14

Photoautotrophic bacteria have developed mechanisms to maintain K(+) homeostasis under conditions of changing ionic concentrations in the environment. Synechocystis sp. strain PCC 6803 contains genes encoding a well-characterized Ktr-type K(+) uptake transporter (Ktr) and a putative ATP-dependent transporter specific for K(+) (Kdp). The contributions of each of these K(+) transport systems to cellular K(+) homeostasis have not yet been defined conclusively. To verify the functionality of Kdp, kdp genes were expressed in Escherichia coli, where Kdp conferred K(+) uptake, albeit with lower rates than were conferred by Ktr. An on-chip microfluidic device enabled monitoring of the biphasic initial volume recovery of single Synechocystis cells after hyperosmotic shock. Here, Ktr functioned as the primary K(+) uptake system during the first recovery phase, whereas Kdp did not contribute significantly. The expression of the kdp operon in Synechocystis was induced by extracellular K(+) depletion. Correspondingly, Kdp-mediated K(+) uptake supported Synechocystis cell growth with trace amounts of external potassium. This induction of kdp expression depended on two adjacent genes, hik20 and rre19, encoding a putative two-component system. The circadian expression of kdp and ktr peaked at subjective dawn, which may support the acquisition of K(+) required for the regular diurnal photosynthetic metabolism. These results indicate that Kdp contributes to the maintenance of a basal intracellular K(+) concentration under conditions of limited K(+) in natural environments, whereas Ktr mediates fast potassium movements in the presence of greater K(+) availability. Through their distinct activities, both Ktr and Kdp coordinate the responses of Synechocystis to changes in K(+) levels under fluctuating environmental conditions.

リンク情報
DOI
https://doi.org/10.1128/JB.02276-14
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/25313394
PubMed Central
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334184

エクスポート
BibTeX RIS