Osmotin Is a Homolog of Mammalian Adiponectin and Controls Apoptosis in Yeast through a Homolog of Mammalian Adiponectin Receptor

Abstract

The antifungal activity of the PR-5 family of plant defense proteins has been suspected to involve specific plasma membrane component(s) of the fungal target. Osmotin is a tobacco PR-5 family protein that induces apoptosis in the yeast Saccharomyces cerevisiae. We show here that the protein encoded by ORE20/PHO36 (YOL002c), a seven transmembrane domain receptor-like polypeptide that regulates lipid and phosphate metabolism, is an osmotin binding plasma membrane protein that is required for full sensitivity to osmotin. PHO36 functions upstream of RAS2 in the osmotin-induced apoptotic pathway. The mammalian homolog of PHO36 is a receptor for the hormone adiponectin and regulates cellular lipid and sugar metabolism. Osmotin and adiponectin, the corresponding "receptor" binding proteins, do not share sequence similarity. However, the beta barrel domain of both proteins can be overlapped, and osmotin, like adiponectin, activates AMP kinase in C2C12 myocytes via adiponectin receptors.

Osmotin induces cold protection in olive trees by affecting programmed cell death and cytoskeleton organization

“…In the present paper we show that osmotin, a plant protein causing PCD in yeast (Narasimhan et al 2001(Narasimhan et al , 2005, also induces PCD in plants. When overexpressed in the stem of olive trees (various clones) which are non-cold-acclimated and not exposed to cold stress, the tissues in which the protein accumulates, e.g.…”

“…During PCD of both animal and plant cells, cytoskeleton alterations occur and are calcium-mediated (Lecourieux et al2002;Hajnoczky et al 2003;Staiger and FranklinTong 2003;Wadhawan et al 2004). A role for osmotin as PCD inducer has also been demonstrated in yeast (Narasimhan et al 2001 and2005) and in human cells cultured in vitro (Risso et al 1998), but information is lacking with regard to plants.…”

Silencing of PR-10-like proteins in Medicago truncatula results in an antagonistic induction of other PR proteins and in an increased tolerance upon infection with the oomycete Aphanomyces euteiches

“…Consequently, an osmotin-like protein was found to bind to phosphomannans in yeast cells, which provides access to a 7-transmembrane-domain receptor-like protein in the plasma membrane that regulates lipid and phosphate metabolism and is homologous to a mammalian hormone receptor (Narasimhan et al 2005). Possibly, functional relationships to PR-10s might exist concerning their ability to bind to BRs.…”

Yeast Saccharomyces cerevisiae adiponectin receptor homolog Izh2 is involved in the regulation of zinc, phospholipid and pH homeostasis

“…IZH2 and especially IZH4 expression has been shown to be regulated also by Mga2 16 , a transcriptional activator that in response to hypoxia induces expression of genes such as OLE1 17 , which encodes the sole fatty acid desaturase in yeast. Izh2 is localized to the plasma membrane and is a putative functional homologue of adiponectin receptors since it binds osmotin, a plant homolog of adiponectin 18 . In addition, heterologous expression of human adiponectin receptors in yeast results in functional complementation of Izh2 in ion homeostasis, and their activation with adiponectin elicits a signaling cascade that includes the same signaling proteins as Izh2p overexpression, such as AMPK/Snf1 19 .…”