title: The circadian clock-related gene pex regulates a negative cis element in the kaiA promoter region.
abstract: In the cyanobacterium Synechococcus sp. strain PCC 7942, a circadian clock-related gene, pex, was identified as the gene prolonging the period of the clock. A PadR domain, which is a newly classified transcription factor domain, and the X-ray crystal structure of the Pex protein suggest a role for Pex in transcriptional regulation in the circadian system. However, the regulatory target of the Pex protein is unknown. To determine the role of Pex, we monitored bioluminescence rhythms that reported the expression activity of the kaiA gene or the kaiBC operon in pex deficiency, pex constitutive expression, and the wild-type genotype. The expression of kaiA in the pex-deficient or constitutive expression genotype was 7 or 1/7 times that of the wild type, respectively, suggesting that kaiA is the target of negative regulation by Pex. In contrast, the expression of the kaiBC gene in the two pex-related genotypes was the same as that in the wild type, suggesting that Pex specifically regulates kaiA expression. We used primer extension analysis to map the transcription start site for the kaiA gene 66 bp upstream of the translation start codon. Mapping with deletion and base pair substitution of the kaiA upstream region revealed that a 5-bp sequence in this region was essential for the regulation of kaiA. The repression or constitutive expression of the kaiA transgene caused the prolongation or shortening of the circadian period, respectively, suggesting that the Pex protein changes the period via the negative regulation of kaiA.
authors: International Graduate School of Arts and Sciences, Yokohama-City University, Japan. kutsuna@yokohama-cu.ac.jp
authors: Shinsuke
authors: S
authors: Kutsuna
authors: Takao
authors: T
authors: Kondo
authors: Haruki
authors: H
authors: Ikegami
authors: Tatsuya
authors: T
authors: Uzumaki
authors: Mitsunori
authors: M
authors: Katayama
authors: Masahiro
authors: M
authors: Ishiura
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002940:Circadian Rhythm; D056925:Circadian Rhythm Signaling Peptides and Proteins; D018360:Crystallography, X-Ray; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D011401:Promoter Regions, Genetic; D046940:Synechococcus / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D056925:Circadian Rhythm Signaling Peptides and Proteins; C114269:KaiA protein, cyanobacteria; C111941:Pex protein, Synechococcus
references: Mol Microbiol. 2005 Sep;57(5):1474-84
references: 16102014
references: EMBO J. 2005 Mar 23;24(6):1202-10
references: 15775978
references: J Biol Chem. 2007 Jan 12;282(2):1128-35
references: 17098741
references: J Bacteriol. 1998 Apr;180(8):2167-74
references: 9555901
references: Science. 1998 Sep 4;281(5382):1519-23
references: 9727980
references: Microbiology. 1995 Apr;141 ( Pt 4):831-41
references: 7773387
references: J Biol Chem. 2003 Jan 24;278(4):2388-95
references: 12441347
references: Plant Physiol. 1991 Sep;97(1):55-9
references: 16668415
references: Methods Enzymol. 1988;167:703-12
references: 3148838
references: J Bacteriol. 2000 Dec;182(23):6724-31
references: 11073918
references: J Biol Rhythms. 2006 Aug;21(4):235-44
references: 16864644
references: Science. 2005 Apr 15;308(5720):414-5
references: 15831759
references: J Bacteriol. 1991 Dec;173(23):7525-33
references: 1938947
references: Science. 2005 Jan 14;307(5707):251-4
references: 15550625
references: Science. 1994 Nov 18;266(5188):1233-6
references: 7973706
references: Curr Opin Microbiol. 1998 Oct;1(5):516-23
references: 10066525
references: Appl Environ Microbiol. 2004 Apr;70(4):2146-53
references: 15066807
references: EMBO J. 2003 May 1;22(9):2127-34
references: 12727879
references: Proc Natl Acad Sci U S A. 2004 Jan 20;101(3):881-5
references: 14709675
references: Microbiology. 2002 Sep;148(Pt 9):2903-9
references: 12213935
references: Proc Natl Acad Sci U S A. 1993 Jun 15;90(12):5672-6
references: 8516317
references: Proc Natl Acad Sci U S A. 2002 Nov 26;99(24):15788-93
references: 12391300
references: J Bacteriol. 1995 Nov;177(22):6676-8
references: 7592451
references: J Bacteriol. 2003 Feb;185(4):1415-22
references: 12562813