NMR studies on Na+ transport in Synechococcus PCC 6311

Nitschmann, W. H.; Packer, L.

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NASA NTRS · 20040112289

NMR studies on Na+ transport in Synechococcus PCC 6311

Nitschmann, W. H.·Packer, L.

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Abstract

The freshwater cyanobacterium Synechococcus PCC 6311 is able to adapt to grow after sudden exposure to salt (NaCl) stress. We have investigated the mechanism of Na+ transport in these cells during adaptation to high salinity. Na+ influx under dark aerobic conditions occurred independently of delta pH or delta psi across the cytoplasmic membrane, ATPase activity, and respiratory electron transport. These findings are consistent with the existence of Na+/monovalent anion cotransport or simultaneous Na+/H+ +anion/OH- exchange. Na+ influx was dependent on Cl-, Br-, NO3-, or NO2-. No Na+ uptake occurred after addition of NaI, NaHCO3, or Na2SO4. Na+ extrusion was absolutely dependent on delta pH and on an ATPase activity and/or on respiratory electron transport. This indicates that Na+ extrusion via Na+/H+ exchange is driven by primary H+ pumps in the cytoplasmic membrane. Cells grown for 4 days in 0.5 m NaCl medium, "salt-grown cells," differ from control cells by a lower maximum velocity of Na+ influx and by lower steady-state ratios of [Na+]in/[Na+]out. These results indicate that cells grown in high-salt medium increase their capacity to extrude Na+. During salt adaptation Na+ extrusion driven by respiratory electron transport increased from about 15 to 50%.

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Non-NASA Center NASA Program CELSS NASA Discipline Life Support Systems NASA Discipline Number 61-10 Biological Transport, Active Synechococcus Group/growth & development/metabolism Sodium Chloride/pharmacology Proton Pumps/metabolism Sodium/pharmacokinetics Magnetic Resonance Spectroscopy Electron Transport/physiology Adenosinetriphosphatase/metabolism Ion Transport Cell Membrane Permeability Support, U.S. Gov't, Non-P.H.S Hydrogen-Ion Concentration Culture Media Time Factors

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Nitschmann, W. H., Packer, L.. 1992-05-01. NMR studies on Na+ transport in Synechococcus PCC 6311. https://ntrs.nasa.gov/citations/20040112289

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