The response of Saccharomyces cerevisiae to osmotic stress, whether arising from environmental conditions or physiological processes, has been intensively studied in the last two decades. The well-known high-osmolarity glycerol (HOG) signalling pathway that is induced in response to osmotic stress interacts with other signalling pathways such as the cell wall integrity and the target of rapamycin pathways. Osmotic balance is also maintained by the regulated opening and closing of channel proteins in both the cell membrane and intracellular organelles such as the vacuole. Additionally, environmental stresses, including osmotic shock, induce intracellular calcium signalling. Thus, adaptation to environmental stresses in general, and osmotic stress in particular, is dependent on the concerted action of components of multiple interacting pathways. In this review, we describe some of the major mechanisms and molecules involved in osmoregulation via pathways other than the high-osmolarity glycerol pathway and their known interactions with one another that have been discovered over the last two decades.
Septins are a conserved family of GTP-binding proteins that are distributed across different lineages of the eukaryotes, with the exception of plants. Septins perform a myriad of functions in fungal cells, ranging from controlling morphogenetic events to contributing to host tissue invasion and virulence. One key attribute of the septins is their ability to assemble into heterooligomeric complexes that organizse into higher order structures. In addition to the established role of septins in the model budding yeast, Saccharomyces cerevisiae, their importance in other fungi recently emerges. While newer roles for septins are being uncovered in these fungi, the mechanism of how septins assemble into a complex and their regulation is only beginning to be comprehended. In this review, we summarize recent findings on the role of septins in different fungi and focus on how the septin complexes of different fungi are organized in vitro and in vivo. Furthermore, we discuss on how phosphorylation/dephosphorylation can serve as an important mechanism of septin complex assembly and regulation.