Journal Article Ahead of print
PubMed: 41871809 DOI: 10.1016/j.jbc.2026.111396
An ancestral glutamate receptor mediates cell volume regulation during high K + stress in cyanobacteria.
J Biol Chem
Authors: Haoyu Zhang, Masaru Tsujii, Ellen Tanudjaja, Haruto Shimizukawa, Yuki Muraoka, Yuki Sato, Kota Kera, Tadaomi Furuta, Shingo Kaneko, Satoshi Amaya, Hirotaka Sugiura, Fumihito Arai, Yasuhiro Ishimaru, Nobuyuki Uozumi
Affiliations
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
- School of Life Science and Technology, Institute of Science Tokyo, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
- Graduate school of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
Abstract
Cyanobacteria, able to survive photoautotrophically in harsh environments, possess various ancestral homologs of ion transport systems found in eukaryotic cells. The model cyanobacterium, Synechocystis sp. PCC 6803 contains five K + channels, however, their function and role have not been fully explained. This study determined the structure, function and physiological role of an ancestral glutamate receptor, GluR0, in Synechocystis. Growth of a gluR0 mutant (ΔgluR0) increased under high KCl conditions. Subcellular fractionation showed that GluR0 was localized in the plasma membrane of Synechocystis, and expression of GluR0 enabled a K + uptake-deficient E. coli mutant to grow under low K + conditions. The membrane topology of GluR0 was opposite to that of the canonical K + channel, but similar to that of the animal glutamate receptor. Microfluidic device-aided single-cell analysis that enabled instantaneous extracellular solution exchange revealed that between 50 and 100 milliseconds after KCl upshock, the cell volume of ΔgluR0 decreased more rapidly than the wild type. These data provide the first direct evidence that a prokaryotic glutamate receptor homolog with K + channel activity plays a role in responding to rapid changes in the ionic environment. This function likely reflects a property of glutamate receptors that was acquired early on during evolution.
MeSH
Cells, Stress, Physiological, Microfluidics, Cyanobacteria, Receptors, Glutamate, Environment, Membranes