A novel membrane protein capable of binding the Na+/H+ antiporter (Nha1p) enhances the salinity-resistant cell growth of Saccharomyces cerevisiae |
| |
Authors: | Mitsui Keiji Ochi Fumihiro Nakamura Norihiro Doi Yoshihide Inoue Hiroki Kanazawa Hiroshi |
| |
Institution: | Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho 1-16, Toynaka City, Osaka 560-0043, Japan. |
| |
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. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|