Alteration of cyanobacterial sugar and amino acid metabolism by overexpression hik8, encoding a KaiC-associated histidine kinase.
Cyanobacteria possess circadian clocks consisting of KaiABC proteins, and circadian rhythm must closely relate to the primary metabolism. A histidine kinase, SasA, interacts with KaiC to transduce circadian signals and widely regulates transcription in Synechococcus sp. PCC 7942, although the involvement of SasA in primary metabolism has not been demonstrated at metabolite levels. Here, we generated a strain overexpressing hik8 (HOX80), an orthologue of SasA in Synechocystis sp. PCC 6803. HOX80 grew slowly under light conditions and lost viability under continuous dark conditions. Transcript levels of genes related to sugar catabolism remained higher in HOX80 under dark conditions. Metabolomic analysis revealed that under light conditions, glycogen was undetectable in HOX80, and there were decreased levels of metabolites of sugar catabolism and increased levels of amino acids, compared with those in the wild-type strain. HOX80 exhibited aberrant degradation of SigE proteins after a light-to-dark transition and immunoprecipitation analysis revealed that Hik8 directly interacts with KaiC1. The results of this study demonstrate that overexpression of hik8 widely alters sugar and amino acid metabolism, revealing the involvement of Hik8 in primary metabolism under both light and dark conditions in this cyanobacterium.
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.|Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
Takashi
T
Osanai
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Tomokazu
T
Shirai
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Hiroko
H
Iijima
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Ayuko
A
Kuwahara
Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan.
Iwane
I
Suzuki
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.|Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokkodai, Nada, Kobe, 657-8501.
Akihiko
A
Kondo
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Masami Yokota
MY
Hirai
D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000235:genetics*; D057906:Circadian Clocks / Q000235:genetics*; D002940:Circadian Rhythm / Q000235:genetics; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006003:Glycogen / Q000378:metabolism; D000071677:Histidine Kinase; D008027:Light; D055432:Metabolomics; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics* / Q000378:metabolism; D046939:Synechocystis / Q000235:genetics* / Q000378:metabolism
D000596:Amino Acids; D001426:Bacterial Proteins; D056925:Circadian Rhythm Signaling Peptides and Proteins; C114271:KaiC protein, cyanobacteria; D006003:Glycogen; D011494:Protein Kinases; D000071677:Histidine Kinase