Guljamow Arthur, Barchewitz Tino, Große Rebecca, Timm Stefan, Hagemann Martin, Dittmann Elke
Department of Microbiology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Street 24/25, 14476 Potsdam-Golm, Germany.
Department of Plant Physiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Street 3, 18059 Rostock, Germany.
Microorganisms. 2021 Jun 10;9(6):1265. doi: 10.3390/microorganisms9061265.
The ubiquitous freshwater cyanobacterium is remarkably successful, showing a high tolerance against fluctuations in environmental conditions. It frequently forms dense blooms which can accumulate significant amounts of the hepatotoxin microcystin, which plays an extracellular role as an infochemical but also acts intracellularly by interacting with proteins of the carbon metabolism, notably with the CO fixing enzyme RubisCO. Here we demonstrate a direct link between external microcystin and its intracellular targets. Monitoring liquid cultures of in a diel experiment revealed fluctuations in the extracellular microcystin content that correlate with an increase in the binding of microcystin to intracellular proteins. Concomitantly, reversible relocation of RubisCO from the cytoplasm to the cell's periphery was observed. These variations in RubisCO localization were especially pronounced with cultures grown at higher cell densities. We replicated these effects by adding microcystin externally to cultures grown under continuous light. Thus, we propose that microcystin may be part of a fast response to conditions of high light and low carbon that contribute to the metabolic flexibility and the success of in the field.
这种无处不在的淡水蓝藻细菌非常成功，对环境条件的波动表现出高度耐受性。它经常形成密集的水华，可积累大量肝毒素微囊藻毒素，微囊藻毒素作为一种信息化学物质在细胞外起作用，但也通过与碳代谢的蛋白质相互作用在细胞内发挥作用，特别是与固定二氧化碳的酶核酮糖-1,5-二磷酸羧化酶/加氧酶（RubisCO）相互作用。在这里，我们证明了细胞外微囊藻毒素与其细胞内靶点之间的直接联系。在一个昼夜实验中监测液体培养物发现，细胞外微囊藻毒素含量的波动与微囊藻毒素与细胞内蛋白质结合的增加相关。同时，观察到核酮糖-1,5-二磷酸羧化酶/加氧酶从细胞质到细胞周边的可逆重新定位。这些核酮糖-1,5-二磷酸羧化酶/加氧酶定位的变化在较高细胞密度下生长的培养物中尤为明显。我们通过向在连续光照下生长的培养物中外部添加微囊藻毒素来复制这些效应。因此，我们提出微囊藻毒素可能是对高光和低碳条件的快速反应的一部分，这有助于其在野外的代谢灵活性和成功生存。
