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| Status |
Public on Oct 28, 2010 |
| Title |
Gene expression under low O2 in Synechocystis sp. PCC 6803 wild type and hik31 mutant |
| Organism |
Synechocystis sp. PCC 6803 |
| Experiment type |
Expression profiling by array
|
| Summary |
We have investigated the response of the cyanobacterium Synechocystis sp. PCC 6803 during growth at very low O2 concentration (bubbled with 99.9% N2/0.1% CO2). Significant transcriptional changes upon low O2 incubation included up-regulation of a cluster of genes that contained psbA1 and an operon that includes a gene encoding the two-component regulatory histidine kinase, Hik31. This regulatory cluster is of particular interest, since there are virtually identical copies on both the chromosome and on plasmid pSYSX. We used a knockout mutant lacking the chromosomal copy of hik31 and studied differential transcription during the aerobic- low O2 transition in this ΔHik31 strain and the wild type. We observed two distinct responses to this transition, one Hik31 dependent, the other Hik31 independent. The Hik31 independent responses included the psbA1 induction and genes involved in chlorophyll biosynthesis. In addition, there were changes in a number of genes that may be in involved in assembling or stabilizing Photosystem II (PSII), and the hox operon and the LexA-like protein (Sll1626) were up-regulated during low O2 growth. This family of responses mostly focused on PSII and overall redox control. There was also a large set of genes that responded differently in the absence of the chromosomal Hik31. In the vast majority of these cases, Hik31 functioned as a repressor and transcription was enhanced when Hik31 was deleted. Genes in this category encoded both core and peripheral proteins for Photosystem I and PS II, the main phycobilisome proteins, chaperones, the ATP synthase cluster and virtually all of the ribosomal proteins. These findings, coupled with the fact that ΔHik31 grew better than the wild-type under low O2 conditions, suggested that Hik31 helped to regulate growth and overall cellular homeostasis. We detected changes in the transcription of other regulatory genes that may compensate for the loss of Hik31. We conclude that Hik31 regulates an important series of genes that relate to energy production and growth and that helps to determine how Synechocystis responds to changes in O2 conditions.
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| Overall design |
The microarray experiment involved a loop design that compared the wild type and the ΔHik31 strain under aerobic conditions and 1 h following a transition to low oxygen by using an ANOVA model. RNA was extracted from three biological replicates of both the wild type and the ΔHik31 mutant. The three replicates of each strain were grown in a photobioreactor with air bubbling and then bubbled with a 99.9% nitrogen/0.1% carbon dioxide mix. Cells were harvested for RNA extraction at t0, prior to bubbling with nitrogen/carbon dioxide and at t1 after 1 h of nitrogen/carbon dioxide bubbling.
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| Citation(s) |
20929957 |
| Submission date |
Oct 21, 2010 |
| Last update date |
Mar 22, 2012 |
| Contact name |
Tina Summerfield |
| E-mail(s) |
tina.summerfield@otago.ac.nz
|
| Phone |
+64 3 4797578
|
| Fax |
+64 3 479 7853
|
| URL |
http://www.botany.otago.ac.nz/people/summerfield.html
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| Organization name |
University of Otago
|
| Department |
Botany
|
| Street address |
464 Great King Street
|
| City |
Dunedin |
| ZIP/Postal code |
9014 |
| Country |
New Zealand |
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| Platforms (1) |
| GPL11088 |
Synechocystis sp. strain PCC 6803 12K full genome array version 4 |
|
| Samples (12)
|
| GSM611733 |
Synechocystis sp. PCC 6803_wild type_aerobic_rep1 |
| GSM611952 |
Synechocystis sp. PCC 6803_wild type_aerobic_t0_rep2 |
| GSM611953 |
Synechocystis sp. PCC 6803_wild type_aerobic_rep3 |
| GSM611954 |
Synechocystis sp. PCC 6803_wild type_LowO2_t1 |
| GSM611955 |
Synechocystis sp. PCC 6803_wild type_LowO2_t1_rep2 |
| GSM611956 |
Synechocystis sp. PCC 6803_wild type_LowO2_t1_rep3 |
| GSM611957 |
Synechocystis sp. PCC 6803_hik31interruption_aerobic_t0_rep1 |
| GSM611958 |
Synechocystis sp. PCC 6803_hik31interruption_aerobic_t0_rep2 |
| GSM611959 |
Synechocystis sp. PCC 6803_hik31interruption_aerobic_t0_rep3 |
| GSM611960 |
Synechocystis sp. PCC 6803_hik31interruption_lowO2_t1_rep1 |
| GSM611961 |
Synechocystis sp. PCC 6803_hik31interruption_lowO2_t1_rep2 |
| GSM611962 |
Synechocystis sp. PCC 6803_hik31interruption_lowO2_t1_rep3 |
|
| Relations |
| BioProject |
PRJNA132025 |
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