Adenyl cyclases and cAMP in plant signaling - past and present

Abstract

In lower eukaryotes and animals 3'-5'-cyclic adenosine monophosphate (cAMP) and adenyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, have long been established as key components and second messengers in many signaling pathways. In contrast, in plants, both the presence and biological role of cAMP have been a matter of ongoing debate and some controversy. Here we shall focus firstly on the discovery of cellular cAMP in plants and evidence for a role of this second messenger in plant signal transduction. Secondly, we shall review current evidence of plant ACs, analyse aspects of their domain organisations and the biological roles of candidate molecules. In addition, we shall assess different approaches based on search motifs consisting of functionally assigned amino acids in the catalytic centre of annotated and/or experimentally tested nucleotide cyclases that can contribute to the identification of novel candidate molecules with AC activity such as F-box and TIR proteins.

A Cyclic Nucleotide-Gated Channel (CNGC16) in Pollen Is Critical for Stress Tolerance in Pollen Reproductive Development

“…Means are shown with SE. within this range, with pollen showing approximately 700-fold less than leaves. Despite this variation, the detected concentrations are consistent with the potential for localized levels of cGMP that are sufficient for activating enzymes such as a CNGC (Gehring, 2010).…”

RETINOBLASTOMA-RELATED PROTEIN controls the transition to autotrophic plant development

“…In Ostreococcus, the metabolic status is signaled via cAMP, which results in the activation of a CyclinA/CDKA complex that inhibits RBR and allows entry into S-phase (Moulager et al, 2010). However, a possible role of cAMP in nutrient signaling in Arabidopsis remains to be identified (Gehring, 2010). Interestingly, in Arabidopsis cell suspension culture, RBR was found to be associated with S6K1 (Henriques et al, 2010), a growth regulator downstream of TOR kinase.…”

Cyclic nucleotide-gated channel 18 is an essential Ca 2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis

“…These data demonstrate that CNGC18 is the main Ca 2+ channel essential for pollen tube guidance in Arabidopsis. CNGCs are downstream targets of cyclic nucleotides (cAMP and cGMP), and cAMP has been reported to function as a second messenger in pollen tube orientation by regulating Ca 2+ channel activity in pollen tubes (34,44,45). Then, we focused on the six CNGCs, especially CNGC18, in further experiments.…”