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Competitive intra- and extracellular nutrient sensing by transporter homologue

Boqian Wu ; Kim Ottow ; Peter Poulsen ; Richard F Gaber ; Eva Albers (Institutionen för kemi- och bioteknik, Molekylär bioteknik) ; Morten C Kielland-Brandt
Journal of Cell Biology (0021-9525). Vol. 173 (2005), 3, p. 327-331.
[Artikel, refereegranskad vetenskaplig]

Recent studies of Saccharomyces cerevisiae revealed sensors that detect extracellular amino acids (Ssy1p) or glucose (Snf3p and Rgt2p) and are evolutionarily related to the transporters of these nutrients. An intriguing question is whether the evolutionary transformation of transporters into nontransporting sensors reflects a homeostatic capability of transporter-like sensors that could not be easily attained by other types of sensors. We previously found SSY1 mutants with an increased basal level of signaling and increased apparent affinity to sensed extracellular amino acids. On this basis, we propose and test a general model for transporter-like sensors in which occupation of a single, central ligand binding site increases the activation energy needed for the conformational shift between an outward-facing, signaling conformation and an inward-facing, nonsignaling conformation. As predicted, intracellular leucine accumulation competitively inhibits sensing of extracellular amino acids. Thus, a single sensor allows the cell to respond to changes in nutrient availability through detection of the relative concentrations of intra- and extracellular ligand.

Nyckelord: Nutrient sensing, SSY1, amino acid sensing, carrier transport



Denna post skapades 2008-09-01. Senast ändrad 2016-06-17.
CPL Pubid: 73384

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Molekylär bioteknik (2005-2007)

Ämnesområden

Biokemi
Molekylärbiologi

Chalmers infrastruktur