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Featured researches published by Michinori Mutsuda.


Proceedings of the National Academy of Sciences of the United States of America | 2009

Cyanobacterial daily life with Kai-based circadian and diurnal genome-wide transcriptional control in Synechococcus elongatus

Hiroshi Ito; Michinori Mutsuda; Yoriko Murayama; Jun Tomita; Norimune Hosokawa; Kazuki Terauchi; Chieko Sugita; Mamoru Sugita; Takao Kondo; Hideo Iwasaki

In the unicellular cyanobacterium Synechococcus elongatus PCC 7942, essentially all promoter activities are under the control of the circadian clock under continuous light (LL) conditions. Here, we used high-density oligonucleotide arrays to explore comprehensive profiles of genome-wide Synechococcus gene expression in wild-type, kaiABC-null, and kaiC-overexpressor strains under LL and continuous dark (DD) conditions. In the wild-type strains, >30% of transcripts oscillated significantly in a circadian fashion, peaking at subjective dawn and dusk. Such circadian control was severely attenuated in kaiABC-null strains. Although it has been proposed that KaiC globally represses gene expression, our analysis revealed that dawn-expressed genes were up-regulated by kaiC-overexpression so that the clock was arrested at subjective dawn. Transfer of cells to DD conditions from LL immediately suppressed expression of most of the genes, while the clock kept even time in the absence of transcriptional feedback. Thus, the Synechococcus genome seems to be primarily regulated by light/dark cycles and is dramatically modified by the protein-based circadian oscillator.


Nature Structural & Molecular Biology | 2007

Autonomous synchronization of the circadian KaiC phosphorylation rhythm

Hiroshi Ito; Hakuto Kageyama; Michinori Mutsuda; Masato Nakajima; Tokitaka Oyama; Takao Kondo

The cyanobacterial circadian oscillator can be reconstituted in vitro by mixing three purified clock proteins, KaiA, KaiB and KaiC, with ATP. The KaiC phosphorylation rhythm persists for at least 10 days without damping. By mixing oscillatory samples that have different phases and analyzing the dynamics of their phase relationships, we found that the robustness of the KaiC phosphorylation rhythm arises from the rapid synchronization of the phosphorylation state and reaction direction (phosphorylation or dephosphorylation) of KaiC proteins. We further demonstrate that synchronization is tightly linked with KaiC dephosphorylation and is mediated by monomer exchange between KaiC hexamers during the early dephosphorylation phase. This autonomous synchronization mechanism is probably the basis for the resilience of the cyanobacterial circadian system against quantitative fluctuations in clock components during cellular events such as cell growth and division.


Journal of Biological Chemistry | 2006

Translation Initiation of Cyanobacterial rbcS mRNAs Requires the 38-kDa Ribosomal Protein S1 but Not the Shine-Dalgarno Sequence DEVELOPMENT OF A CYANOBACTERIAL IN VITRO TRANSLATION SYSTEM

Michinori Mutsuda; Masahiro Sugiura

Little is known about the biochemical mechanism of translation in cyanobacteria though substantial studies have been made on photosynthesis, nitrogen fixation, circadian rhythm, and genome structure. To analyze the mechanism of cyanobacterial translation, we have developed an in vitro translation system from Synechococcus cells using a psbAI-lacZ fusion mRNA as a model template. This in vitro system supports accurate translation from the authentic initiation site of a variety of Synechococcus mRNAs. In Synechococcus cells, rbcL and rbcS encoding the large and small subunits, respectively, of ribulose-1,5-bisphosphate carboxylase/oxygenase are co-transcribed as a dicistronic mRNA, and the downstream rbcS mRNA possesses two possible initiation codons separated by three nucleotides. Using this in vitro system and mutated mRNAs, we demonstrated that translation starts exclusively from the upstream AUG codon. Although there are Shine-Dalgarno-like sequences in positions similar to those of the functional Shine-Dalgarno elements in Escherichia coli, mutation analysis indicated that these sequences are not required for translation. Assays with deletions within the 5′-untranslated region showed that a pyrimidine-rich sequence in the –46 to –15 region is necessary for efficient translation. Synechococcus cells contain two ribosomal protein S1 homologues of 38 and 33 kDa in size. UV cross-linking and immunoprecipitation experiments suggested that the 38-kDa S1 is involved in efficient translation via associating with the pyrimidine-rich sequence. The present in vitro translation system will be a powerful tool to analyze the basic mechanism of translation in cyanobacteria.


Archive | 1998

The Function of the Cyanobacterial RNA-Binding Proteins

Michinori Mutsuda; Tetsuro Hirose; Masahiro Sugiura; Mamoru Sugita

Posttranscriptional and translational regulation of gene expression in cyanobacteria have recently been reported (1-3). The different stability of mRNAs is suggested to have an important role for the regulation of psbA gene expression (3). In our laboratory, to identify the proteins involved in these steps, we previously separated many single stranded DNA binding proteins from Synechococcus sp. PCC 6301 (4-6) and found two distinct 12 kDa RNA binding proteins, Rbpl and Rbp2 (4, 7). These proteins contain a conserved ribonucleoprotein consensus sequence (RNP-CS)-type RNA binding domain (CS-RBD) of 82 amino acids. Rbpl has a glycine rich C-terminal sequence and the expression of rbpl gene is enhanced by cold stress or under growth condition of high light intensity while rbp2 gene expression does not exhibit such a mode (4, Mutsuda et al., unpublished).


Fems Microbiology Letters | 1999

Targeted deletion of genes for eukaryotic RNA‐binding proteins, Rbp1 and Rbp2, in the cyanobacterium Synechococcus sp. strain PCC7942: Rbp1 is indispensable for cell growth at low temperatures

Chieko Sugita; Michinori Mutsuda; Masahiro Sugiura; Mamoru Sugita


Plant and Cell Physiology | 1999

Physiological Characterization of RNA-Binding Protein-Deficient Cells from Synechococcus sp. Strain PCC7942

Michinori Mutsuda; Masahiro Sugiura; Mamoru Sugita


Seibutsu Butsuri | 2007

1P300 Synchronization and singularity behavior of a reconstituted circadian clock in vitro(Mathematical biology, biological rythms, and non-equilibrium phenomena,Oral Presentations)

Hiroshi Ito; Maho Miyazaki; Hakuto Kageyama; Michinori Mutsuda; Tokitaka Oyama; Takao Kondo


Seibutsu Butsuri | 2006

2P065 Synchronization of a circadian clock in vitro(30. Protein function (II),Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

Hiroshi Ito; Michinori Mutsuda; Hakuto Kageyama; Tokitaka Oyama; Takao Kondo


Plant and Cell Physiology | 2000

THE ANALYSIS OF TRANSLATION MECHANISM FOR rbcS mRNA FROM Synechococcus sp

Michinori Mutsuda; Mamoru Sugita; Masahiro Sugiura


Plant and Cell Physiology | 1995

ENZYMATIC AND MOLECULAR CHARACTERIZATIONOF CATALASE IN Synechococcus PCC 7942

Michinori Mutsuda; Miyuki Kimoto; Takahiro Ishikawa; Toru Takeda; Osamu Hirayama; Shigeru Shigeoka

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