title: Sequence determinants of circadian gene expression phase in cyanobacteria.
abstract: The cyanobacterium Synechococcus elongatus PCC 7942 exhibits global biphasic circadian oscillations in gene expression under constant-light conditions. Class I genes are maximally expressed in the subjective dusk, whereas class II genes are maximally expressed in the subjective dawn. Here, we identify sequence features that encode the phase of circadian gene expression. We find that, for multiple genes, an ∼70-nucleotide promoter fragment is sufficient to specify class I or II phase. We demonstrate that the gene expression phase can be changed by random mutagenesis and that a single-nucleotide substitution is sufficient to change the phase. Our study provides insight into how the gene expression phase is encoded in the cyanobacterial genome.
authors.affiliation: Graduate Program in Systems Biology, Harvard University, Cambridge, MA, USA.
authors.forename: Vikram
authors.initials: V
authors.lastname: Vijayan
authors.forename: Erin K
authors.initials: EK
authors.lastname: O'Shea
mesh_terms: D001483:Base Sequence; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology* / Q000528:radiation effects; D005805:Genes, MHC Class I / Q000502:physiology* / Q000528:radiation effects; D005802:Genes, MHC Class II / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D008163:Luminescent Measurements; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D046940:Synechococcus / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D008164:Luminescent Proteins