The conserved active site aspartate residue is required for the function of the chloroplast atypical kinase ABC1K1.

INTRODUCTION: The Arabidopsis abc1k1/pgr6 (Activity of BC1 complex/proton regulation 6) mutant is characterized by photosynthetic and conditional developmental phenotypes triggered by stressful red as well as high light. The Arabidopsis ABC1-like kinases belong to the atypical kinase family and contain conserved ATP-binding and hydrolysis motifs, but their physiological requirement has never been investigated. METHODS: By mutation to asparagine, we demonstrate that the highly conserved active site aspartate residue within ATP-binding motif VIIb is required for the physiological functions of ABC1K1. RESULTS: Complementation of the abc1k1 knock out mutant with ABC1K1 D400N, failed to restore the wildtype phenotype. DISCUSSION: These results provide in vivo evidence for a critical role of the active site aspartate residue (D400) of ABC1K1.