Multicopper oxidases have a wide range of substrate specificity to be involved in various physiological reactions. Pseudomonas syringae, a plant pathogenic bacterium, has a multicopper oxidase, CumA. Multicopper oxidases have ability to degrade plant cell wall component, lignin. Once P. syringae enter apoplast and colonize, they start to disrupt plant immunity. Therefore, deeper understanding of multicopper oxidases from plant pathogens helps to invent measures to prevent invasion into plant cell, which brings agricultural benefits. Several biochemical studies have reported lower activity of CumA compared with other multicopper oxidase called CotA. However, the mechanisms underlying the difference in activity have not yet been revealed. In order to acquire insight into them, we conducted a biophysical characterization of PsCumA. Our results show that PsCumA has weak type I copper EPR signal, which is essential for oxidation activity. We propose that difference in the coordination of copper ions may decrease reaction frequency.

中文翻译：

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来自植物病原体丁香假单胞菌的 CumA 多铜氧化酶的生化特性。

多铜氧化酶具有广泛的底物特异性，可参与各种生理反应。丁香假单胞菌是一种植物病原菌，具有多铜氧化酶 CumA。多铜氧化酶具有降解植物细胞壁成分木质素的能力。一旦丁香假单胞菌进入质外体并定殖，它们就会开始破坏植物的免疫力。因此，更深入地了解植物病原体中的多铜氧化酶有助于发明防止入侵植物细胞的措施，从而带来农业效益。几项生化研究报告称，与其他称为 CotA 的多铜氧化酶相比，CumA 的活性较低。然而，活性差异背后的机制尚未揭示。为了深入了解它们，我们对 PsCumA 进行了生物物理表征。我们的研究结果表明，PsCumA 具有较弱的 I 型铜 EPR 信号，这对氧化活性至关重要。我们提出铜离子配位的差异可能会降低反应频率。