Ghorbel Mouna, Feki Kaouthar, Tounsi Sana, Haddaji Najla, Hanin Moez, Brini Faiçal
Biology Department, Faculty of Science, University of Hail, Hai'l P.O. Box 2440, Saudi Arabia.
Laboratory of Biotechnology and Plant Improvement, Center of Biotechnology of Sfax, P.O. Box 1177, Sfax 3018, Tunisia.
Antioxidants (Basel). 2022 Jul 29;11(8):1483. doi: 10.3390/antiox11081483.
Plant catalases (CAT) are involved in the cellular scavenging of the reactive oxygen species during developmental processes and in response to abiotic and biotic stresses. However, little is known about the regulation of the CAT activity to ensure efficient antioxidant function. Using bioinformatic analyses, we showed that durum wheat catalase 1 (TdCAT1) harbors highly conserved cation-binding and calmodulin binding (CaMBD) domains which are localized at different positions of the protein. As a result, the catalytic activity of TdCAT1 is enhanced in vitro by the divalent cations Mn and Fe and to a lesser extent by Cu, Zn, and Mg. Moreover, the GST-pull down assays performed here revealed that TdCAT1 bind to the wheat CaM (TdCaM1.3) in a Ca-independent manner. Furthermore, the TdCaM1.3/Ca complex is stimulated in a CaM-dose-dependent manner by the catalytic activity of TdCAT1, which is further increased in the presence of Mn cations. The catalase activity of TdCAT1 is enhanced by various divalent cations and TdCaM1.3 in a Ca-dependent manner. Such effects are not reported so far and raise a possible role of CaM and cations in the function of CATs during cellular response to oxidative stress.
植物过氧化氢酶（CAT）在发育过程中以及对非生物和生物胁迫的响应中参与细胞内活性氧的清除。然而，关于CAT活性的调节以确保有效的抗氧化功能，人们了解甚少。通过生物信息学分析，我们发现硬粒小麦过氧化氢酶1（TdCAT1）具有高度保守的阳离子结合和钙调蛋白结合（CaMBD）结构域，它们位于蛋白质的不同位置。因此，二价阳离子Mn和Fe在体外增强了TdCAT1的催化活性，而Cu、Zn和Mg的增强作用较小。此外，此处进行的GST下拉试验表明，TdCAT1以不依赖Ca的方式与小麦钙调蛋白（TdCaM1.3）结合。此外，TdCaM1.3/Ca复合物以CaM剂量依赖的方式受到TdCAT1催化活性的刺激，在Mn阳离子存在的情况下进一步增强。TdCAT1的过氧化氢酶活性以Ca依赖的方式被各种二价阳离子和TdCaM1.3增强。目前尚未报道此类效应，这表明钙调蛋白和阳离子在细胞对氧化应激反应过程中CAT功能中可能发挥作用。
