The Arabidopsis thaliana K+‐uptake permease 7 (AtKUP7) contains a functional cytosolic adenylate cyclase catalytic centre

Abstract

Adenylate cyclases (ACs) catalyse the formation of the second messenger cyclic adenosine 3′,5′‐monophosphate (cAMP) from adenosine 5′‐triphosphate (ATP). Although cAMP is increasingly recognised as an important signalling molecule in higher plants, ACs have remained somewhat elusive. Here we used a search motif derived from experimentally tested guanylyl cyclases (GCs), substituted the residues essential for substrate specificity and identified the Arabidopsis thaliana K+‐uptake permease 7 (AtKUP7) as one of several candidate ACs. Firstly, we show that a recombinant N‐terminal, cytosolic domain of AtKUP71‐100 is able to complement the AC‐deficient mutant cyaA in Escherichia coli and thus restoring the fermentation of lactose, and secondly, we demonstrate with both enzyme immunoassays and mass spectrometry that a recombinant AtKUP71‐100 generates cAMP in vitro.