title: Mutations in CHLOROPLAST RNA BINDING provide evidence for the involvement of the chloroplast in the regulation of the circadian clock in Arabidopsis.
abstract: The Arabidopsis circadian system regulates the expression of up to 36% of the nuclear genome, including many genes that encode photosynthetic proteins. The expression of nuclear-encoded photosynthesis genes is also regulated by signals from the chloroplasts, a process known as retrograde signaling. We have identified CHLOROPLAST RNA BINDING (CRB), a putative RNA-binding protein, and have shown that it is important for the proper functioning of the chloroplast. crb plants are smaller and paler than wild-type plants, and have altered chloroplast morphology and photosynthetic performance. Surprisingly, mutations in CRB also affect the circadian system, altering the expression of both oscillator and output genes. In order to determine whether the changes in circadian gene expression are specific to mutations in the CRB gene, or are more generally caused by the malfunctioning of the chloroplast, we also examined the circadian system in mutations affecting STN7, GUN1, and GUN5, unrelated nuclear-encoded chloroplast proteins known to be involved in retrograde signaling. Our results provide evidence that the functional state of the chloroplast may be an important factor that affects the circadian system.
authors.affiliation: Department of Plant and Environmental Sciences, Institute for Life Sciences, Hebrew University, Givat Ram, Jerusalem 91904, Israel.
authors.forename: Miriam
authors.initials: M
authors.lastname: Hassidim
authors.forename: Esther
authors.initials: E
authors.lastname: Yakir
authors.forename: David
authors.initials: D
authors.lastname: Fradkin
authors.forename: Dror
authors.initials: D
authors.lastname: Hilman
authors.forename: Ido
authors.initials: I
authors.lastname: Kron
authors.forename: Nir
authors.initials: N
authors.lastname: Keren
authors.forename: Yael
authors.initials: Y
authors.lastname: Harir
authors.forename: Shai
authors.initials: S
authors.lastname: Yerushalmi
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Green
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D002940:Circadian Rhythm / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D018749:RNA, Plant; D016601:RNA-Binding Proteins