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Light Sensing Gene Expression Project
Genome-Wide Analysis of Light Sensing In Prochlorococcus
J Bacteriol. 2006 Nov;188(22):7796-806. Epub 2006 Sep 15.

Abstract
Prochlorococcus MED4 has, with a total of only 1,716 annotated protein-coding genes, the most compact genome of a free-living photoautotroph. Although light quality and quantity play an important role in regulating the growth rate of this organism in its natural habitat, the majority of known light-sensing proteins are absent from its genome. To explore the potential for light sensing in this phototroph, we measured its global gene expression pattern in response to different light qualities and quantities by using high-density Affymetrix microarrays. Though seven different conditions were tested, only blue light elicited a strong response. In addition, hierarchical clustering revealed that the responses to high white light and blue light were very similar and different from that of the lower-intensity white light, suggesting that the actual sensing of high light is mediated via a blue-light receptor. Bacterial cryptochromes seem to be good candidates for the blue-light sensors. The existence of a signaling pathway for the redox state of the photosynthetic electron transport chain was suggested by the presence of genes that responded similarly to red and blue light as well as genes that responded to the addition of DCMU [3-(3,4-dichlorophenyl)-1,1-N-N'-dimethylurea], a specific inhibitor of photosystem II-mediated electron transport.

Download: Supplementary Data

Pubmed: 16980454

Experiments
Link Control Treatment Note
Browse Dark: 45 min High light: 45 min MED4 only.
Browse Dark: 45 min Red light: 45 min MED4 only.
Browse Dark: 45 min White light: 45 min MED4 only.
Browse Dark: 45 min Blue light: 45 min MED4 only.
Browse Dark: 45 min Green light: 45 min MED4 only.
Browse White light: 45 min White light+DCMU: 45 min MED4 only.