The NAD Kinase Slr0400 Functions as a Growth Repressor in Synechocystis sp. PCC 6803

Yuuma Ishikawa, Cedric Cassan, Aikeranmu Kadeer, Koki Yuasa, Nozomu Sato, Kintake Sonoike, Yasuko Kaneko, Atsuko Miyagi, Hiroko Takahashi, Toshiki Ishikawa, Masatoshi Yamaguchi, Yoshitaka Nishiyama, Yukako Hihara, Yves Gibon, Maki Kawai-Yamada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in the unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the Photosystem II (PSII) photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain the photosynthetic capacity.

Original languageEnglish
Pages (from-to)668-677
Number of pages10
JournalPlant and Cell Physiology
Volume62
Issue number4
DOIs
Publication statusPublished - 2021 Apr 1
Externally publishedYes

Keywords

  • Cyanobacteria
  • Growth repressor
  • NAD kinase
  • Slr0400
  • Synechocystis sp. PCC 6803

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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