Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina.
J Exp Bot. 2011 Aug;62(12):4281-94. doi: 10.1093/jxb/err138. Epub 2011 May 4.
Two Arabidopsis thaliana genes (HCC1 and HCC2), resulting from a duplication that took place before the emergence of flowering plants, encode proteins with homology to the SCO proteins involved in copper insertion during cytochrome c oxidase (COX) assembly in other organisms. Heterozygote HCC1 mutant plants produce 25% abnormal seeds with defective embryos arrested at the heart or torpedo stage. These embryos lack COX activity, suggesting that the requirement of HCC1 during the early stages of plant development is related with its COX assembly function. Homozygote HCC2 mutant plants develop normally and do not show changes in COX2 levels. These plants display increased sensitivity of root growth to increased copper and a higher expression of miR398 and other genes that respond to copper limitation, in spite of the fact that they have a higher copper content than the wild type. HCC2 mutant plants also show increased expression of stress-responsive genes. The results suggest that HCC1 is the protein involved in COX biogenesis and that HCC2, that lacks the cysteines and histidine putatively involved in copper binding, functions in copper sensing and redox homeostasis. In addition, plants that overexpress HCC1 have an altered response of root elongation to changes in copper in the growth medium and increased expression of two low-copper-responsive genes, suggesting that HCC1 may also have a role in copper homeostasis.
两个拟南芥基因（HCC1 和 HCC2），是在开花植物出现之前发生的重复事件的结果，编码的蛋白质与其他生物体中细胞色素 c 氧化酶（COX）组装过程中涉及铜插入的 SCO 蛋白具有同源性。杂合 HCC1 突变体植物产生 25%的异常种子，胚胎缺陷停留在心脏或鱼雷阶段。这些胚胎缺乏 COX 活性，表明 HCC1 在植物发育的早期阶段的需求与其 COX 组装功能有关。纯合 HCC2 突变体植物发育正常，COX2 水平没有变化。这些植物对增加的铜的根生长的敏感性增加，并且对铜限制有更高的表达 miR398 和其他基因，尽管它们的铜含量高于野生型。HCC2 突变体植物也显示出应激响应基因的表达增加。结果表明，HCC1 是参与 COX 生物发生的蛋白质，而 HCC2 缺乏可能参与铜结合的半胱氨酸和组氨酸，在铜感应和氧化还原平衡中起作用。此外，过表达 HCC1 的植物对生长介质中铜变化的根伸长反应发生改变，并且两个低铜响应基因的表达增加，表明 HCC1 也可能在铜平衡中起作用。
