A scenario for the origin of life: Volume regulation by bacteriorhodopsin required extremely voltage sensitive Na-channels and very selective K-channels.
Bioessays
; 44(10): e2100210, 2022 Oct.
Article
in En
| MEDLINE
| ID: mdl-35986436
The osmotic activity produced by internal, non-permeable, anionic nucleic acids and metabolites causes a persistent and life-threatening cell swelling, or cellular edema, produced by the Gibbs-Donnan effect. This evolutionary-critical osmotic challenge must have been resolved by LUCA or its ancestors, but we lack a cell-physiology look into the biophysical constraints to the solutions. Like mycoplasma, early cells conceivably preserved their volume with Cl- , Na+ , and K+ -channels, Na+ /H+ -exchangers, and a light-dependent bacteriorhodopsin-like H+ -pump. Here, I simulated protocells having these ionic-permeabilities and inhabiting an oceanic pond before the Great-Oxygenation-Event. Protocells showed better volume control and stable resting potentials at lower external pH and higher temperatures, favoring a certain type of extremophile life. Prevention of Na+ -influx at night, with low bacteriorhodopsin activity, required deep shutdown of highly voltage-sensitive Na+ -channels and extremely selective K+ -channels, two conserved features essential for modern neuronal encoding. The Gibbs-Donnan effect universality implies that extraterrestrial cells, if they exist, may reveal similar volume-controlling mechanisms.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacteriorhodopsins
/
Nucleic Acids
Type of study:
Diagnostic_studies
Language:
En
Journal:
Bioessays
Journal subject:
BIOLOGIA
/
BIOLOGIA MOLECULAR
Year:
2022
Document type:
Article
Affiliation country:
Chile
Country of publication:
United States