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J Biol Chem. 2014 Sep 5;289(36):24801-9. doi: 10.1074/jbc.M114.583674. Epub 2014 Jul 24.

Cyanobacteriochrome SesA is a diguanylate cyclase that induces cell aggregation in Thermosynechococcus.

Author information

1
From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and.
2
Department of Biological Science, Graduate School of Sciences, University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902.
3
the Life Science Research Center, Shimadzu Corp., 3-1 Kanda-Nishikicho, Chiyoda-ku, Tokyo 108-8639, and.
4
From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and PRESTO and.
5
From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and Department of Biological Science, Graduate School of Sciences, University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan mikeuchi@bio.c.u-tokyo.ac.jp.

Abstract

Cyanobacteria have unique photoreceptors, cyanobacteriochromes, that show diverse spectral properties to sense near-UV/visible lights. Certain cyanobacteriochromes have been shown to regulate cellular phototaxis or chromatic acclimation of photosynthetic pigments. Some cyanobacteriochromes have output domains involved in bacterial signaling using a second messenger cyclic dimeric GMP (c-di-GMP), but its role in cyanobacteria remains elusive. Here, we characterize the recombinant Tlr0924 from a thermophilic cyanobacterium Thermosynechococcus elongatus, which was expressed in a cyanobacterial system. The protein reversibly photoconverts between blue- and green-absorbing forms, which is consistent with the protein prepared from Escherichia coli, and has diguanylate cyclase activity, which is enhanced 38-fold by blue light compared with green light. Therefore, Tlr0924 is a blue light-activated diguanylate cyclase. The protein's relatively low affinity (10.5 mM) for Mg(2+), which is essential for diguanylate cyclase activity, suggests that Mg(2+) might also regulate c-di-GMP signaling. Finally, we show that blue light irradiation under low temperature is responsible for Thermosynechococcus vulcanus cell aggregation, which is abolished when tlr0924 is disrupted, suggesting that Tlr0924 mediates blue light-induced cell aggregation by producing c-di-GMP. Given our results, we propose the name "sesA (sessility-A)" for tlr0924. This is the first report for cyanobacteriochrome-dependent regulation of a sessile/planktonic lifestyle in cyanobacteria via c-di-GMP.

KEYWORDS:

Bacterial Signal Transduction; Cell Aggregation; Cyanobacteria; Cyanobacteriochrome; Cyclic di-GMP (c-di-GMP); Microbiology; Photoreceptor; Sessility; Thermosynechococcus

PMID:
25059661
PMCID:
PMC4155649
DOI:
10.1074/jbc.M114.583674
[Indexed for MEDLINE]
Free PMC Article

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