Sodium-coupled motility in a swimming cyanobacterium.
The energetics of motility in Synechococcus strain WH8113 were studied to understand the unique nonflagellar swimming of this cyanobacterium. There was a specific sodium requirement for motility such that cells were immotile below 10 mM external sodium and cell speed increased with increasing sodium levels above 10 mM to a maximum of about 15 microns/s at 150 to 250 mM sodium. The sodium motive force increased similarly with increasing external sodium from -120 to -165 mV, but other energetic parameters including proton motive force, electrical potential, the proton diffusion gradient, and the sodium diffusion gradient did not show such a correlation. Over a range of external sodium concentrations, cell speed was greater in alkaline environments than in neutral or acidic environments. Monensin and carbonyl cyanide m-chlorophenylhydrazone inhibited motility and affected components of sodium motive force but did not affect ATP levels. Cells were motile when incubated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea and arsenate, which decreased cellular ATP to about 2% of control values. The results of this investigation are consistent with the conclusion that the direct source of energy for Synechococcus motility is a sodium motive force and that below a threshold of about -100 mV, cells are immotile.
D000255:Adenosine Triphosphate / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D000458:Cyanobacteria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008985:Monensin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology
D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate; D008985:Monensin; D012964:Sodium