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Arch Biochem Biophys. 2015 Jun 1;575:61-8. doi: 10.1016/j.abb.2015.04.002. Epub 2015 Apr 20.

Characterization and physiological role of two types of chloroplastic fructose-1,6-bisphosphatases in Euglena gracilis.

Author information

1
Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan.
2
Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan. Electronic address: tamoi@nara.kindai.ac.jp.
3
Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0076, Japan; Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan.

Abstract

The chloroplastic fructose-1,6-bisphosphatase (FBPase) is a late-limiting enzyme in the Calvin cycle. In the present study, we isolated and characterized the cDNAs encoding two types of chloroplastic FBPase isoforms (EgFBPaseI and II) from Euglena gracilis. The Km values of recombinant EgFBPaseI and EgFBPaseII for fructose 1,6-bisphosphate (Fru 1,6-P2) were 165 ± 17 and 2200 ± 200 μM, respectively. The activity of EgFBPaseI was inhibited by 1mM H2O2 and recovered when incubated with DTT. The activity of EgFBPaseII was resistant to concentrations of H2O2 up to 1mM, which was distinct from those of EgFBPaseI and spinach chloroplastic FBPase. The suppression of EgFBPaseI gene expression by gene silencing markedly decreased photosynthetic activity and inhibited cell growth. The results of the present study clearly demonstrated that EgFBPaseI played a critical role in photosynthesis in Euglena chloroplasts.

KEYWORDS:

Euglena gracilis; Fructose-1,6-bisphosphatase; Photosynthesis

PMID:
25906744
DOI:
10.1016/j.abb.2015.04.002
[Indexed for MEDLINE]

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