An Arabidopsis Pentatricopeptide Repeat Is a Moonlighting Protein with Cross-talking In Vitro Adenylyl Cyclase and Kinase Activities

Abstract Downstream signalling involving adenylyl cyclases (ACs) and kinases is a key component of several processes in plants including cell division, growth, response to stress. ACs are enzymes that generate the second messenger molecule, 3′,5′-cyclic adenosine monophosphate (cAMP) from 5′-adenosine triphosphate (ATP) while catalyze addition phosphate group other molecules (trans-phosphorylation) or themselves (auto-phosphorylation). Apparently, there has been an expanded record various identified plants, no plant molecule date shown possess both AC kinase activities/functions with such having characteristic cross-talking interactions. Therefore, endeavor find we searched amino acid sequence known Arabidopsis AC, pentatricopeptide repeat (AtPPR) protein, found kinase-specific signature (KSSS), which speculated be working synergy center this protein during downstream signalling. So, order test if additional catalytically active perhaps also some interactions center, cloned, expressed, affinity purified truncated version AtPPR, harboring KSSS centers (AtPPR-AC/K). When tested vitro, recombinant AtPPR-AC/K showed Mn 2+ -dependent activity positively enhanced by Ca HCO 3 − trans-/auto-phosphorylation capable utilizing ATP GTP as substrates specific serine, threonine, tyrosine acids target residues. In addition, was reduced cAMP at same time, it totally shut down . This thus qualified molecular switches modulators, regulating AtPPR functions through between activities its two domains. Our work, therefore, essentially established first member new class moonlighting proteins have themselves, conceivably presenting ideal candidate for further explorations improve particularly agricultural crops.