title: A network of genes regulated by light in cyanobacteria.
abstract: Oxygenic photosynthetic organisms require light for their growth and development. However, exposure to high light is detrimental to them. Using time series microarray data from a model cyanobacterium, Synechocystis 6803 transferred from low to high light, we generated a gene co-expression network. The network has twelve sub-networks connected hierarchically, each consisting of an interconnected hub-and-spoke architecture. Within each sub-network, edges formed between genes that recapitulate known pathways. Analysis of the expression profiles shows that the cells undergo a phase transition 6-hours post-shift to high light, characterized by core sub-network. The core sub-network is enriched in proteins that (putatively) bind Fe-S clusters and proteins that mediate iron and sulfate homeostasis. At the center of this core is a sulfate permease, suggesting sulfate is rate limiting for cells grown in high light. To validate this novel finding, we demonstrate the limited ability of cell growth in sulfate-depleted medium in high light. This study highlights how understanding the organization of the networks can provide insights into the coordination of physiologic responses.
authors.affiliation: Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA. aurorar@slu.edu
authors.forename: Rajeev
authors.initials: R
authors.lastname: Aurora
authors.forename: Yukako
authors.initials: Y
authors.lastname: Hihara
authors.forename: Abhay K
authors.initials: AK
authors.lastname: Singh
authors.forename: Himadri B
authors.initials: HB
authors.lastname: Pakrasi
mesh_terms: D000458:Cyanobacteria / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D008027:Light; D008954:Models, Biological