Identification of a putative kinase interacting domain in the durum wheat catalase 1 (TdCAT1) protein

Catalases are crucial antioxidant enzymes that regulate plants responses to different biotic and abiotic stresses. It has been previously shown that the activities of durum wheat catalase proteins (TdCAT1) were stimulated in the presence of divalent cations Mn²⁺, Mg²⁺, Fe²⁺, Zn²⁺, and Ca²⁺. In addition, TdCAT1s can interact with calmodulins in calcium-independent manner, and this interaction stimulates its catalytic activity in a calcium-dependent manner. Moreover, this activity is further enhanced by Mn²⁺ cations. The current study showed that wheat catalase presents different phosphorylation targets. Besides, we demonstrated that catalase is able to interact with Mitogen Activated Proteins kinases via a conserved domain. This interaction activates wheat catalase independently of its phosphorylation status but is more promoted by Mn²⁺, Fe²⁺ and Ca²⁺ divalent cations. Interestingly, we have demonstrated that durum wheat catalase activity is differentially regulated by Mitogen Activated Proteins kinases and Calmodulins in the presence of calcium. Moreover, the V0 of the reaction increase gradually following the increasing quantities of Mn²⁺ divalent cations. Such results have never been described before and suggest i) complex regulatory mechanisms exerted on wheat catalase, ii) divalent cations (Mn²⁺; Mg²⁺; Ca²⁺ and Fe²⁺) act as key cofactors in these regulatory mechanisms.