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A putative magnesium transporter Slr1216 involved in sodium tolerance in cyanobacterium Synechocystis sp. PCC 6803

Li, Ting, Zhang, Yanan, Shi, Mengliang, Pei, Guangsheng, Chen, Lei, Zhang, Weiwen
Algal research 2016 v.17 pp. 202-210
Synechocystis sp. PCC 6714, Synechocystis sp. PCC 6803, gas chromatography-mass spectrometry, gene targeting, genes, knockout mutants, magnesium, models, salinity, salt stress, salt tolerance, screening, sodium, solutes
In the model cyanobacterium Synechocystis sp. PCC 6803, the details of cellular response networks to high and fluctuating salinity are not immediately available. In this study, by screening gene knockout mutants of 58 Synechocystis transporter-encoding genes under salt stress, we found the mutant of slr1216, annotated as a magnesium transporter-encoding gene in Cyanobase, was less tolerant to salt than the wild type. Meanwhile, the tolerance loss can be recovered to the similar level of the wild type by complementing the slr1216 gene to the ∆slr1216 mutant, suggesting that slr1216 may be involved in salt tolerance in Synechocystis. The following GC–MS analysis showed that the content of glucosylglycerol (GG), one major compatible solute against salt stress, was lower in the ∆slr1216 mutant than that of the wild type, while the GG content was also recovered to a similar level of the wild type in the complementation strain. In addition, the positive effect of exogenously provided GG on growth of the ∆slr1216 mutant under salt stress was observed. Together, the results showed the transporter Slr1216 might be involved in salt tolerance by affecting intracellular GG concentration, which provided new insight into the complex cellular response networks to salt stress in Synechocystis.