Rensing Christopher, McDevitt Sylvia Franke
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1870, Frederiksberg C, Denmark.
Met Ions Life Sci. 2013;12:417-50. doi: 10.1007/978-94-007-5561-1_12.
As a trace element copper has an important role in cellular function like many other transition metals. Its ability to undergo redox changes [Cu(I) ↔ Cu(II)] makes copper an ideal cofactor in enzymes catalyzing electron transfers. However, this redox change makes copper dangerous for a cell since it is able to be involved in Fenton-like reactions creating reactive oxygen species (ROS). Cu(I) also is a strong soft metal and can attack and destroy iron-sulfur clusters thereby releasing iron which can in turn cause oxidative stress. Therefore, copper homeostasis has to be highly balanced to ensure proper cellular function while avoiding cell damage.Throughout evolution bacteria and archaea have developed a highly regulated balance in copper metabolism. While for many prokaryotes copper uptake seems to be unspecific, others have developed highly sophisticated uptake mechanisms to ensure the availability of sufficient amounts of copper. Within the cytoplasm copper is sequestered by various proteins and molecules, including specific copper chaperones, to prevent cellular damage. Copper-containing proteins are usually located in the cytoplasmic membrane with the catalytic domain facing the periplasm, in the periplasm of Gram-negative bacteria, or they are secreted, limiting the necessity of copper to accumulate in the cytoplasm. To prevent cellular damage due to excess copper, bacteria and archaea have developed various copper detoxification strategies. In this chapter we attempt to give an overview of the mechanisms employed by bacteria and archaea to handle copper and the importance of the metal for cellular function as well as in the global nutrient cycle.
作为一种微量元素，铜与许多其他过渡金属一样，在细胞功能中起着重要作用。其进行氧化还原变化的能力（Cu(I) ↔ Cu(II)）使铜成为催化电子转移的酶中理想的辅助因子。然而，这种氧化还原变化对细胞来说是危险的，因为它能够参与类芬顿反应，产生活性氧（ROS）。Cu(I)也是一种强软金属，能够攻击并破坏铁硫簇，从而释放出铁，进而导致氧化应激。因此，铜稳态必须高度平衡，以确保细胞功能正常，同时避免细胞损伤。
在整个进化过程中，细菌和古菌在铜代谢方面形成了高度调控的平衡。虽然对于许多原核生物来说，铜的摄取似乎是非特异性的，但其他生物已经发展出高度复杂的摄取机制，以确保有足够量的铜可用。在细胞质中，铜被各种蛋白质和分子螯合，包括特定的铜伴侣蛋白，以防止细胞损伤。含铜蛋白通常位于细胞质膜上，催化结构域面向周质，存在于革兰氏阴性菌的周质中，或者它们被分泌出来，从而限制了铜在细胞质中积累的必要性。为了防止因铜过量而造成细胞损伤，细菌和古菌已经发展出各种铜解毒策略。在本章中，我们试图概述细菌和古菌处理铜所采用的机制，以及这种金属对细胞功能和全球营养循环的重要性。
