Two CaMK genes with different biochemical characteristics exist in Magnaporthe oryzae

Two types of Ca²⁺/calmodulin-dependent protein kinase (CaMK) were found in Magnaporthe oryzae. MgCaMK1 and MgCaMK2 were both cloned and sequenced. High similarities in amino acid sequence to other reported CaMKs in fungi suggested that CaMKs were relatively conserved. Both MgCaMK1 and MgCaMK2 have a serine/threonine protein kinase active site and a calmodulin (CaM)-binding domain. Southern blot analysis showed that MgCaMK1 or MgCaMK2 existed as a single copy in the M. oryzae genome. Subsequently, MgCaMK1 or MgCaMK2 was expressed in Escherichia coli BL21 via a pET-32a (+) plasmid. The purified proteins exhibited protein kinase activity. The autophosphorylation and substrate phosphorylation of MgCaMK1 exhibited a Ca²⁺/calmodulin-dependent manner, and suggested that it belonged to the group of Ca²⁺/calmodulin-dependent protein kinases. However, the autophosphorylation and substrate phosphorylation of MgCaMK2 exhibited a Ca²⁺-dependent manner and suggested that it belonged to the group of Ca²⁺-dependent protein kinases.