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| Status |
Public on Nov 30, 2009 |
| Title |
Oscillations in supercoiling drive circadian gene expression in cyanobacteria |
| Organism |
Synechococcus elongatus PCC 7942 = FACHB-805 |
| Experiment type |
Expression profiling by array
|
| Summary |
The cyanobacterium Synechococcus elongatus PCC 7942 exhibits oscillations in mRNA transcript abundance with 24-hour periodicity under continuous light conditions. The mechanism underlying these oscillations remains elusive – neither cis nor trans-factors controlling circadian gene expression phase have been identified. Here we show that the topological status of the chromosome is highly correlated with circadian gene expression state. We also demonstrate that DNA sequence characteristics of genes that appear monotonically activated and monotonically repressed by chromosomal relaxation during the circadian cycle are similar to those of supercoiling responsive genes in E. coli. Furthermore, perturbation of superhelical status within the physiological range elicits global changes in gene expression similar to those that occur during the normal circadian cycle.
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| Overall design |
Synechococcus elongatus PCC 7942 was subjected to two consecutive light/dark cycles and released into continuous light (T = 0). Cells were sampled every 4 hours from T = 24 to T = 84 hours for microarray analysis to characterize circadian gene expression. In a separate experiment, to characterize the response of S. elongatus to immediate chromosome relaxation, cells were sampled at T = 56 and T = 64 hours, immediately followed by novobiocin treatment (0.1 ug/ml), and the resulting response was measured by microarray after 5, 10, 30, 90, and 150 minutes. This experiment was designed to test whether chromosomal relaxation is sufficient to induce gene expression changes similar to those observed during the circadian cycle.
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| Contributor(s) |
Vijayan V, Zuzow R, O'Shea EK |
| Citation(s) |
20018699 |
| |
| Submission date |
Nov 05, 2009 |
| Last update date |
Mar 21, 2012 |
| Contact name |
Vikram Vijayan |
| E-mail(s) |
vvijayan@fas.harvard.edu
|
| Organization name |
Harvard University
|
| Street address |
52 Oxford Street, Room 440
|
| City |
Cambridge |
| State/province |
MA |
| ZIP/Postal code |
02138 |
| Country |
USA |
| |
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| Platforms (1) |
| GPL9534 |
Agilent-020846 Synechococcus elongatus PCC 7942 Oligo Microarray |
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| Samples (23)
|
| GSM468463 |
continuous light T = 24 hours experiment 1 |
| GSM468464 |
continuous light T = 28 hours experiment 1 |
| GSM468465 |
continuous light T = 32 hours experiment 1 |
| GSM468466 |
continuous light T = 36 hours experiment 1 |
| GSM468467 |
continuous light T = 40 hours experiment 1 |
| GSM468468 |
continuous light T = 44 hours experiment 1 |
| GSM468469 |
continuous light T = 48 hours experiment 1 |
| GSM468470 |
continuous light T = 52 hours experiment 1 |
| GSM468471 |
continuous light T = 56 hours experiment 1 |
| GSM468472 |
continuous light T = 60 hours experiment 1 |
| GSM468473 |
continuous light T = 64 hours experiment 1 |
| GSM468474 |
continuous light T = 68 hours experiment 1 |
| GSM468475 |
continuous light T = 72 hours experiment 1 |
| GSM468476 |
continuous light T = 76 hours experiment 1 |
| GSM468477 |
continuous light T = 80 hours experiment 1 |
| GSM468478 |
continuous light T = 84 hours experiment 1 |
| GSM468479 |
novobiocin T = 56 hours experiment 2 |
| GSM468480 |
novobiocin T = 64 hours experiment 2 |
| GSM468481 |
novobiocin T = 5 minutes experiment 2 |
| GSM468482 |
novobiocin T = 10 minutes experiment 2 |
| GSM468483 |
novobiocin T = 30 minutes experiment 2 |
| GSM468484 |
novobiocin T = 90 minutes experiment 2 |
| GSM468485 |
novobiocin T = 150 minutes experiment 2 |
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| Relations |
| BioProject |
PRJNA121309 |
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