A novel membrane protein capable of binding the Na+/H+ antiporter (Nha1p) enhances the salinity-resistant cell growth of Saccharomyces cerevisiae

J Biol Chem. 2004 Mar 26;279(13):12438-47. doi: 10.1074/jbc.M310806200. Epub 2004 Jan 12.

Abstract

The Na+/H+ antiporter Nha1p of Saccharomyces cerevisiae plays an important role in maintaining intracellular pH and Na+ homeostasis. Nha1p has a two-domain structure composed of integral membrane and hydrophilic tail regions. Overexpression of a peptide of approximately 40 residues (C1+C2 domains) that is localized in the juxtamembrane area of its cytoplasmic tail caused cell growth retardation in highly saline conditions, possibly by decreasing Na+/H+ antiporter activity. A multicopy suppressor gene of this growth retardation was identified from a yeast genome library. The clone encodes a novel membrane protein denoted as COS3 in the genome data base. Overexpression or deletion of COS3 increases or decreases salinity-resistant cell growth, respectively. However, in nha1Delta cells, overexpression of COS3 alone did not suppress the growth retardation. Cos3p and a hydrophilic portion of Cos3p interact with the C1+C2 peptide in vitro, and Cos3p is co-precipitated with Nha1p from yeast cell extracts. Cos3p-GFP mainly resides at the vacuole, but overexpression of Nha1p caused a portion of the Cos3p-GFP proteins to shift to the cytoplasmic membrane. These observations suggest that Cos3p is a novel membrane protein that can enhance salinity-resistant cell growth by interacting with the C1+C2 domain of Nha1p and thereby possibly activating the antiporter activity of this protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cation Transport Proteins / chemistry*
  • Cation Transport Proteins / metabolism*
  • Cell Division
  • Cell Membrane / metabolism*
  • Centrifugation, Density Gradient
  • Cytoplasm / metabolism
  • DNA Primers / pharmacology
  • Dose-Response Relationship, Drug
  • Gene Library
  • Genes, Dominant
  • Genes, Fungal
  • Green Fluorescent Proteins
  • Luminescent Proteins / metabolism
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism*
  • Membrane Proteins / physiology*
  • Molecular Sequence Data
  • Open Reading Frames
  • Peptides / chemistry
  • Plasmids / metabolism
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / physiology*
  • Sequence Homology, Amino Acid
  • Sodium Chloride / pharmacology*
  • Sodium-Hydrogen Exchangers / chemistry*
  • Sodium-Hydrogen Exchangers / metabolism*
  • Subcellular Fractions
  • Time Factors

Substances

  • COS3 protein, S cerevisiae
  • Cation Transport Proteins
  • DNA Primers
  • Luminescent Proteins
  • Membrane Proteins
  • NHA1 protein, S cerevisiae
  • Peptides
  • Saccharomyces cerevisiae Proteins
  • Sodium-Hydrogen Exchangers
  • Green Fluorescent Proteins
  • Sodium Chloride