Format

Send to

Choose Destination
Cell. 2009 Jul 10;138(1):160-71. doi: 10.1016/j.cell.2009.04.047.

A systems-level analysis of perfect adaptation in yeast osmoregulation.

Author information

1
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Abstract

Negative feedback can serve many different cellular functions, including noise reduction in transcriptional networks and the creation of circadian oscillations. However, only one special type of negative feedback ("integral feedback") ensures perfect adaptation, where steady-state output is independent of steady-state input. Here we quantitatively measure single-cell dynamics in the Saccharomyces cerevisiae hyperosmotic shock network, which regulates membrane turgor pressure. Importantly, we find that the nuclear enrichment of the MAP kinase Hog1 perfectly adapts to changes in external osmolarity, a feature robust to signaling fidelity and operating with very low noise. By monitoring multiple system quantities (e.g., cell volume, Hog1, glycerol) and using varied input waveforms (e.g., steps and ramps), we assess in a minimally invasive manner the network location of the mechanism responsible for perfect adaptation. We conclude that the system contains only one effective integrating mechanism, which requires Hog1 kinase activity and regulates glycerol synthesis but not leakage.

PMID:
19596242
PMCID:
PMC3109981
DOI:
10.1016/j.cell.2009.04.047
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center