Mantovani Oliver, Reimann Viktoria, Haffner Michael, Herrmann Felix Philipp, Selim Khaled A, Forchhammer Karl, Hess Wolfgang R, Hagemann Martin
Department of Plant Physiology, Institute of Biosciences, University of Rostock, Rostock, D-18059, Germany.
Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, D-79104, Germany.
New Phytol. 2022 Jun;234(5):1801-1816. doi: 10.1111/nph.18094. Epub 2022 Apr 9.
The amount of inorganic carbon (C ) fluctuates in aquatic environments. Cyanobacteria evolved a C -concentrating mechanism (CCM) that is regulated at different levels. The regulator SbtB binds to the second messengers cAMP or c-di-AMP and is involved in acclimation to low C (LC) in Synechocystis sp. PCC 6803. Here, we investigated the role of SbtB and of associated second messengers at different C conditions. The transcriptome of wild-type (WT) Synechocystis and the ΔsbtB mutant were compared with Δcya1, a mutant defective in cAMP production, and ΔdacA, a mutant defective in generating c-di-AMP. A defined subset of LC-regulated genes in the WT was already changed in ΔsbtB under high C (HC) conditions. This response of ΔsbtB correlated with a diminished induction of many CCM-associated genes after LC shift in this mutant. The Δcya1 mutant showed less deviation from WT, whereas ΔdacA induced CCM-associated genes under HC. Metabolome analysis also revealed differences between the strains, whereby ΔsbtB showed slower accumulation of 2-phosphoglycolate and ΔdacA differences among amino acids compared to WT. Collectively, these results indicate that SbtB regulates a subset of LC acclimation genes while c-di-AMP and especially cAMP appear to have a lesser impact on gene expression under different C availabilities.
水生环境中无机碳（C）的含量会发生波动。蓝细菌进化出了一种在不同水平上受到调控的碳浓缩机制（CCM）。调节因子SbtB与第二信使环磷酸腺苷（cAMP）或环二腺苷酸（c-di-AMP）结合，并参与集胞藻PCC 6803对低碳（LC）的适应过程。在此，我们研究了SbtB以及相关第二信使在不同碳条件下的作用。将野生型（WT）集胞藻和ΔsbtB突变体的转录组与cAMP产生缺陷的突变体Δcya1以及c-di-AMP产生缺陷的突变体ΔdacA进行了比较。在高碳（HC）条件下，WT中受LC调控的特定基因子集在ΔsbtB中已经发生了变化。ΔsbtB的这种反应与该突变体在从HC转变为LC后许多与CCM相关基因的诱导减弱相关。Δcya1突变体与WT的偏差较小，而ΔdacA在HC条件下诱导了与CCM相关的基因。代谢组分析也揭示了这些菌株之间的差异，与WT相比，ΔsbtB显示2-磷酸乙醇酸的积累较慢，而ΔdacA显示氨基酸存在差异。总的来说，这些结果表明SbtB调节了一部分LC适应基因，而c-di-AMP，尤其是cAMP在不同碳可用性下对基因表达的影响似乎较小。
