A <i>Colletotrichum</i>-unique effector with the Cx₁₁NC motif enhances plant NDPK2 kinase activity to suppress plant immunity.

Abstract

<i>Colletotrichum</i> fungi cause destructive diseases among a wide range of hosts worldwide. We found that effector CfEC92 from <i>C. fructicola</i> specifically binds ATP through an unidentified ATP-binding domain, leading to changes in the protein secondary structure. The residues Cys²⁶, Asn³⁸, and Cys³⁹ were critical for ATP binding with CfEC92, and mutations at these sites impaired the ability to suppress host immunity. CfEC92 interacted with MdNDPK2, a negative immune regulator in apple. The CfEC92-ATP complex altered the conformation of MdNDPK2, enhancing its affinity for ATP, and further increasing its autophosphorylation and kinase activity. The activated MdNDPK2 phosphorylated MdMPK3 to suppress host immunity. Homology and functional tests showed that the Cx₁₁NC motif was highly conserved among <i>Colletotrichum</i> species, suggesting that CNC effectors represent a class of broad-spectrum virulence factors. Our findings revealed a mechanism by which <i>Colletotrichum</i> effectors cooperate with helper ATP to promote target protein phosphorylation and suppress host immunity.