Effect of cations on the structure of bilayers formed by lipopolysaccharides isolated from Pseudomonas aeruginosa PAO1.
The asymmetric outer membrane of Gram-negative bacteria contains lipopolysaccharides (LPSs) which contribute significantly to the bacterium's surface properties and play a crucial role in regulating membrane permeability. We report on neutron diffraction studies performed on aligned, self-assembled bilayers of Na-, Ca-, and Mg-salt forms of LPS isolated from Pseudomonas aeruginosa PAO1. From the one-dimensional neutron scattering length density profiles we find that water penetrates Ca2+-LPS bilayers to a lesser extent than either Na+- or Mg2+-LPS bilayers. This differential water penetration could have implications as to how small molecules permeate the outer membrane of Gram-negative bacteria and, possibly, how nonlamellar phases are formed.
Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario K0J 1J0, Canada.
Norbert
N
Kucerka
Erzsebet
E
Papp-Szabo
Mu-Ping
MP
Nieh
Thad A
TA
Harroun
Sarah R
SR
Schooling
Jeremy
J
Pencer
Eric A
EA
Nicholson
Terry J
TJ
Beveridge
John
J
Katsaras
D002412:Cations / Q000494:pharmacology*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D008670:Metals / Q000494:pharmacology*; D033363:Neutron Diffraction; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D014867:Water / Q000378:metabolism
D002412:Cations; D008051:Lipid Bilayers; D008070:Lipopolysaccharides; D008670:Metals; D014867:Water