Ca2+-dependent interaction between calmodulin and CoDN3, an effector of Colletotrichum orbiculare.

Nuclear magnetic resonance (NMR) data directly indicated a Ca2+-dependent interaction between calmodulin (CaM) and CoDN3, a small effector of the plant pathogenic fungus Colletotrichum orbiculare, which is the causal agent of cucumber anthracnose. The overall conformation of CoDN3 is intrinsically disordered, and the CaM-binding site spans residues 34–53 of its C-terminal region. Experiments employing a chemically synthesized peptide corresponding to the CaM-binding site indicated that the CaM-binding region of CoDN3 in the Ca2+-bound CaM complex takes an α-helical conformation. Cell death suppression assay using a CoDN3 mutant lacking the CaM-binding ability suggested that the wild type CaM-binding site is necessary for full CoDN3 function in vivo. • CoDN3, an effector of the pathogenic microbe Colletotrichum orbiculare , interacts with calmodulin (CaM). • The binding between CoDN3 and CaM occurs in a Ca2+-dependent manner. • The CaM-bindings site of CoDN3 is located at its C-terminal half region, and is necessary for full CoDN3 function in vivo. • CoDN3 is an intrinsically disordered protein, but the CaM-binding region forms helical conformation when it binds to CaM. [ABSTRACT FROM AUTHOR]