14-3-3 Proteins in Guard Cell Signaling
Abstract
Guard cells are specialized cells located at the leaf surface delimiting pores which
control gas exchanges between the plant and the atmosphere. To optimize the CO$_2$
uptake necessary for photosynthesis while minimizing water loss, guard cells integrate
environmental signals to adjust stomatal aperture. The size of the stomatal pore is
regulated by movements of the guard cells driven by variations in their volume and
turgor. As guard cells perceive and transduce a wide array of environmental cues, they
provide an ideal system to elucidate early events of plant signaling. Reversible protein
phosphorylation events are known to play a crucial role in the regulation of stomatal
movements. However, in some cases, phosphorylation alone is not sufficient to achieve
complete protein regulation, but is necessary to mediate the binding of interactors
that modulate protein function. Among the phosphopeptide-binding proteins, the 14-
3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple
isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal
movements. In this review, we describe the current knowledge about 14-3-3 roles in
the regulation of their binding partners in guard cells: receptors, ion pumps, channels,
protein kinases, and some of their substrates. Regulation of these targets by 14-3-
3 proteins is discussed and related to their function in guard cells during stomatal
movements in response to abiotic or biotic stresses.
Origin : Publisher files allowed on an open archive
Loading...