Moenne Alejandra, Gómez Melissa, Laporte Daniel, Espinoza Daniela, Sáez Claudio A, González Alberto
Laboratory of Marine Biotechnology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 916000, Chile.
Laboratory of Aquatic Environmental Research, Centro de Estudios Avanzados, Universidad de Playa Ancha, Viña del Mar 2520000, Chile.
Plants (Basel). 2020 May 27;9(6):681. doi: 10.3390/plants9060681.
Copper induces an oxidative stress condition in the marine alga that is due to the production of superoxide anions and hydrogen peroxide, mainly in organelles. The increase in hydrogen peroxide is accompanied by increases in intracellular calcium and nitric oxide, and there is a crosstalk among these signals. The increase in intracellular calcium activates signaling pathways involving Calmodulin-dependent Protein Kinases (CaMKs) and Calcium-Dependent Protein Kinases (CDPKs), leading to activation of gene expression of antioxidant enzymes and enzymes involved in ascorbate (ASC) and glutathione (GSH) synthesis. It was recently shown that copper also activates Mitogen-Activated Protein Kinases (MAPKs) that participate in the increase in the expression of antioxidant enzymes. The increase in gene expression leads to enhanced activities of antioxidant enzymes and to enhanced levels of ASC and GSH. In addition, copper induces an increase in photosynthesis leading to an increase in the leve of Nicotinamide Adenine Dinucleotide Phosphate (NADPH). Copper also induces an increase in activities of enzymes involved in C, N, and S assimilation, allowing the replacement of proteins damaged by oxidative stress. The accumulation of copper in acute exposure involved increases in GSH, phytochelatins (PCs), and metallothioneins (MTs) whereas the accumulation of copper in chronic exposure involved only MTs. Acute and chronic copper exposure induced the accumulation of copper-containing particles in chloroplasts. On the other hand, copper is extruded from the alga with an equimolar amount of GSH. Thus, the increases in activities of antioxidant enzymes, in ASC, GSH, and NADPH levels, and in C, N, and S assimilation, the accumulation of copper-containing particles in chloroplasts, and the extrusion of copper ions from the alga constitute essential mechanisms that participate in the buffering of copper-induced oxidative stress in
铜会在海洋藻类中引发氧化应激状态，这是由于超氧阴离子和过氧化氢的产生，主要发生在细胞器中。过氧化氢的增加伴随着细胞内钙和一氧化氮的增加，并且这些信号之间存在相互作用。细胞内钙的增加会激活涉及钙调蛋白依赖性蛋白激酶（CaMKs）和钙依赖性蛋白激酶（CDPKs）的信号通路，从而导致抗氧化酶以及参与抗坏血酸（ASC）和谷胱甘肽（GSH）合成的酶的基因表达激活。最近研究表明，铜还会激活丝裂原活化蛋白激酶（MAPKs），其参与抗氧化酶表达的增加。基因表达的增加导致抗氧化酶活性增强以及ASC和GSH水平升高。此外，铜会促使光合作用增强，导致烟酰胺腺嘌呤二核苷酸磷酸（NADPH）水平升高。铜还会促使参与碳、氮和硫同化的酶的活性增加，从而能够替换因氧化应激而受损的蛋白质。急性暴露中铜的积累涉及GSH、植物螯合肽（PCs）和金属硫蛋白（MTs）的增加，而慢性暴露中铜的积累仅涉及MTs。急性和慢性铜暴露都会导致叶绿体中含铜颗粒的积累。另一方面，铜会与等摩尔量的GSH一起从藻类中排出。因此，抗氧化酶活性的增加、ASC、GSH和NADPH水平的升高、碳、氮和硫同化的增加、叶绿体中含铜颗粒的积累以及铜离子从藻类中的排出，构成了参与缓冲铜诱导的氧化应激的重要机制。
