Direct sensing of nutrient availability by fungi

Nutrients can be monitored directly when they bind to a sensing protein to initiate a conformational change. G protein-coupled receptors are a good example of this type of sensing and ligand binding has been proposed as the initiating sensing event that regulates other types of nutrient sensors. This review will analyse the role of two distinct types of fungal regulators that may fall in this category. Ammonium transporters are essential for various developmental processes and may respond to ammonium binding by interacting with signal transduction pathways to initiate signalling. In the nucleus, copper responsive genes are regulated by transcription factors that are proposed to undergo copper-induced intramolecular interactions that inhibit their activity. Although in each case the model of ligand initiated allosteric regulation is attractive, we do not yet fully understand the molecular basis of sensing by these molecules.

► Ammonium sensing for pseudohyphal growth requires ammonium transport by specific permease.
► Copper transcription factors may bind copper in a sensing role.
► Ligand induced conformational changes may regulate range of fungal nutrient sensors.