Molecular characterisation and expression of an Arabidopsis thaliana L. MAP kinase kinase cDNA, AtMAP2Kα

During our study of the mitogen-activated protein (MAP) kinase module in higher plants, we have isolated and characterised an Arabidopsis thaliana cDNA: AtMAP2K alpha, a novel member of the MAP kinase kinase family. The cDNA was obtained by screening a library from A. thaliana plantlets using the A. thaliana EST clone 127H15T7 as a probe. The deduced protein contains 348 residues with a calculated molecular mass of 38.3 kDa. A relationship analysis using MAP2K catalytic domain sequences from mammals, insect, fungi, yeasts, nematode, protists and plants showed that the plant gene family identified to date encodes a distinct group of proteins. The results also indicate that AtMAP2K alpha is a member of a subgroup of MAP kinase kinases in plants. Signature sequences were identified that characterise either all MAP2Ks or only plant MAP2Ks. A Northern blot analysis revealed that the AtMAP2K alpha transcripts were mostly detected in vegetative tissues from A. thaliana and Brassica napus plants. In both species, high transcript levels were found in leaves and seedlings, while much lower levels of expression were detected in inflorescences and roots from A. thaliana and immature siliques from B. napus. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.