PAAI is a P-Type ATPase that functions to import copper (Cu) into the chloroplast. Arabidopsis thaliana (L.) Heynh. paa1 mutants have lowered plastocyanin levels, resulting in a decreased photosynthetic electron transport rate. In nature, iron (Fe) and Cu homeostasis are often linked and it can be envisioned that paa1 acclimates its photosynthetic machinery by adjusting expression of its chloroplast Fe-proteome, but outside of Cu homeostasis paa1 has not been studied. Here, we characterise paa1 ultrastructure and accumulation of electron transport chain proteins in a paa1 allelic series. Furthermore, using hydroponic growth conditions, we characterised metal homeostasis in paa1 with an emphasis on the effects of Fe deficiency. Surprisingly, the paa1 mutation does not affect chloroplast ultrastructure or the accumulation of other photosynthetic electron transport chain proteins, despite the strong decrease in electron transport rate. The regulation of Fe-related photosynthetic electron transport proteins in response to Fe status was maintained in paa1, suggesting that regulation of the chloroplast Fe proteins ignores operational signals from photosynthetic output. The characterisation of paa1 has revealed new insight into the regulation of expression of the photosynthetic electron transport chain proteins and chloroplast metal homeostasis and can help to develop new strategies for the detection of shoot Fe deficiency.

中文翻译：

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微量营养素稳态和叶绿体铁蛋白表达在叶绿体铜转运蛋白突变体中基本维持

PAAI 是一种 P 型 ATP 酶，其功能是将铜 (Cu) 导入叶绿体。拟南芥 (L.) Heynh。paa1 突变体降低了质体蓝素水平，导致光合电子传递速率降低。在自然界中，铁 (Fe) 和 Cu 稳态通常是相关联的，可以设想 paa1 通过调整其叶绿体 Fe 蛋白质组的表达来适应其光合作用机制，但在 Cu 稳态之外 paa1 尚未被研究。在这里，我们描述了 paa1 等位基因系列中电子传递链蛋白的 paa1 超微结构和积累。此外，使用水培生长条件，我们表征了 paa1 中的金属稳态，重点是缺铁的影响。出奇，paa1 突变不影响叶绿体超微结构或其他光合电子传递链蛋白的积累，尽管电子传递速率显着下降。响应于 Fe 状态的 Fe 相关光合电子传递蛋白的调节在 paa1 中得以维持，这表明叶绿体 Fe 蛋白的调节忽略了来自光合输出的操作信号。paa1 的表征揭示了对光合电子传递链蛋白表达调控和叶绿体金属稳态的新见解，并有助于开发检测地上部铁缺乏的新策略。响应于 Fe 状态的 Fe 相关光合电子传递蛋白的调节在 paa1 中得以维持，这表明叶绿体 Fe 蛋白的调节忽略了来自光合输出的操作信号。paa1 的表征揭示了对光合电子传递链蛋白表达调控和叶绿体金属稳态的新见解，并有助于开发检测地上部铁缺乏的新策略。响应于 Fe 状态的 Fe 相关光合电子传递蛋白的调节在 paa1 中得以维持，这表明叶绿体 Fe 蛋白的调节忽略了来自光合输出的操作信号。paa1 的表征揭示了对光合电子传递链蛋白表达调控和叶绿体金属稳态的新见解，并有助于开发检测地上部铁缺乏的新策略。