Cloning of a Ca 2+/calmodulin-dependent protein kinase gene from the filamentous fungus Arthrobotrys dactyloides

Abstract

A Ca 2+/calmodulin-dependent protein kinase (CaMK) gene was cloned and characterized from Arthrobotrys dactyloides, a nematode-trapping fungus. The resulting 373-amino-acid protein, FCaMK, has significant homology to mammalian CaMKs. FCaMK contains a serine/threonine kinase domain followed by a calmodulin-binding domain. The activation loop in FCaMK (amino acids 184–199) contains a phosphorylation site at threonine-188, which could be the target of a kinase activator. Truncated FCaMK mutants revealed that amino acids 296–324 are essential for calmodulin binding. An oligopeptide designed from residues 297–324 formed a stable peptide–calmodulin complex of 1:1 stoichiometry. Southern blot analysis detected a single copy of the fcamk gene, suggesting that FCaMK plays an important role in Ca 2+/calmodulin signaling in A. dactyloides.