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Global transcriptional response of the alkali-tolerant cyanobacterium Synechocystis sp. strain PCC 6803 to a pH 10 environment.

Abstract：

:Many cyanobacterial strains are able to grow at a pH range from neutral to pH 10 or 11. Such alkaline conditions favor cyanobacterial growth (e.g., bloom formation), and cyanobacteria must have developed strategies to adjust to changes in CO2 concentration and ion availability. Synechocystis sp. strain PCC 6803 exhibits similar photoautotrophic growth characteristics at pH 10 and pH 7.5, and we examined global gene expression following transfer from pH 7.5 to pH 10 to determine cellular adaptations at an elevated pH. The strategies used to develop homeostasis at alkaline pH had elements similar to those of many bacteria, as well as components unique to phototrophic microbes. Some of the response mechanisms previously identified in other bacteria included upregulation of Na+/H+ antiporters, deaminases, and ATP synthase. In addition, upregulated genes encoded transporters with the potential to contribute to osmotic, pH, and ion homeostasis (e.g., a water channel protein, a large-conductance mechanosensitive channel, a putative anion efflux transporter, a hexose/proton symporter, and ABC transporters of unidentified substrates). Transcriptional changes specific to photosynthetic microbes involved NADH dehydrogenases and CO2 fixation. The pH transition altered the CO2/HCO3(-) ratio within the cell, and the upregulation of three inducible bicarbonate transporters (BCT1, SbtA, and NDH-1S) likely reflected a response to this perturbed ratio. Consistent with this was increased transcript abundance of genes encoding carboxysome structural proteins and carbonic anhydrase. Interestingly, the transition to pH 10 resulted in increased abundance of transcripts of photosystem II genes encoding extrinsic and low-molecular-weight polypeptides, although there was little change in photosystem I gene transcripts.

journal_name

Appl Environ Microbiol

journal_title

Applied and environmental microbiology

authors

Summerfield TC,Sherman LA

doi

10.1128/AEM.00883-08

subject

Has Abstract

pub_date

2008-09-01 00:00:00

pages

5276-84

issue

eissn

0099-2240

issn

1098-5336

pii

AEM.00883-08

journal_volume

pub_type

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Global transcriptional response of the alkali-tolerant cyanobacterium Synechocystis sp. strain PCC 6803 to a pH 10 environment.