TY - JOUR
T1 - Damped circadian oscillation in the absence of KaiA in Synechococcus
AU - Kawamoto, Naohiro
AU - Ito, Hiroshi
AU - Tokuda, Isao T.
AU - Iwasaki, Hideo
N1 - Funding Information:
We thank K. Miwa and T. Kondo for providing recombinant mutant KaiC proteins, C.H. Johnson, and Y. Xu for valuable discussion. We also thank Y. Murayama, K. Kawasaki, and other members of the Iwasaki Laboratory for valuable comments and technical support. This study was supported in part by a Grant-in-Aid for Scientific Research (KAKENHI) from JSPS (Grant nos. 18K19349 and 23657138 to H. Iwasaki, 18H05474 to H. Ito, and 17H06313 to I.T.T.). The authors would like to thank Enago for the English language review.
Publisher Copyright:
© 2020, The Author(s).
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in the cyanobacterium Synechococcus elongatus. It has been reported kaiA inactivation completely abolishes circadian oscillations. However, we show here that kaiBC promoter activity exhibits a damped, low-amplitude oscillation with a period of approximately 24 h in kaiA-inactivated strains. The damped rhythm resonates with external cycles with a period of 24–26 h, indicating that its natural frequency is similar to that of the circadian clock. Double-mutation experiments reveal that kaiC, kaiB, and sasA (encoding a KaiC-binding histidine kinase) are all required for the damped oscillation. Further analysis suggests that the kaiA-less damped transcriptional rhythm requires KaiB-KaiC complex formation and the transcription-translation feedback loop, but not the KaiC phosphorylation cycle. Our results provide insights into mechanisms that could potentially underlie the diurnal/circadian behaviors observed in other bacterial species that possess kaiB and kaiC homologues but lack a kaiA homologue.
AB - Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in the cyanobacterium Synechococcus elongatus. It has been reported kaiA inactivation completely abolishes circadian oscillations. However, we show here that kaiBC promoter activity exhibits a damped, low-amplitude oscillation with a period of approximately 24 h in kaiA-inactivated strains. The damped rhythm resonates with external cycles with a period of 24–26 h, indicating that its natural frequency is similar to that of the circadian clock. Double-mutation experiments reveal that kaiC, kaiB, and sasA (encoding a KaiC-binding histidine kinase) are all required for the damped oscillation. Further analysis suggests that the kaiA-less damped transcriptional rhythm requires KaiB-KaiC complex formation and the transcription-translation feedback loop, but not the KaiC phosphorylation cycle. Our results provide insights into mechanisms that could potentially underlie the diurnal/circadian behaviors observed in other bacterial species that possess kaiB and kaiC homologues but lack a kaiA homologue.
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U2 - 10.1038/s41467-020-16087-x
DO - 10.1038/s41467-020-16087-x
M3 - Article
C2 - 32382052
AN - SCOPUS:85084391812
SN - 2041-1723
VL - 11
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 2242
ER -