Anionic phospholipids in the control of the membrane surface potential in Escherichia coli: their influence on transport mechanisms.
1. Phosphatidylserine (PS)-rich Escherichia coli cells were utilized to investigate the role of anionic phospholipids on membrane surface potential and their effect upon active transport mechanisms. 2. It was found that: 3. The transport of inorganic phosphate and glutamate, which depends upon cations, was increased (Km decreases) in PS-rich cells as compared to normal cells. 4. The reduction of the negative surface potential by MgCl2 or by the cationic local anesthetic procaine, brought about a decrement in the uptake of both substrates. 5. When the negative surface potential of the PS-rich cells was reduced, the Km returned back to the values found in normal cells. 6. A direct correlation between the ratio anionic/zwitterionic phospholipids, negative surface potential and increment in the initial rate of transport was found.
Cerbón
J
J
Department of Biochemistry, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F.
Hernández Luna
C
C
D000838:Anions; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007700:Kinetics; D015636:Magnesium Chloride / Q000494:pharmacology; D008564:Membrane Potentials; D010710:Phosphates / Q000378:metabolism; D010718:Phosphatidylserines / Q000494:pharmacology / Q000502:physiology; D010743:Phospholipids / Q000502:physiology*; D011343:Procaine / Q000494:pharmacology
D000838:Anions; D005971:Glutamates; D010710:Phosphates; D010718:Phosphatidylserines; D010743:Phospholipids; D015636:Magnesium Chloride; D018698:Glutamic Acid; D011343:Procaine