OmpT: Molecular Dynamics Simulations of an Outer Membrane Enzyme
Topic: 1H Membrane Proteins ; 8E
Molecular Dynamics
Presentation Time: Monday, 10:45 a.m.
Marc Baaden1, Mark S. P. Sansom2.
1IBPC, CNRS UPR9080, Paris, France, 2University
of Oxford, Oxford, United Kingdom.
Presentation Number: 911-Plat
MD
simulations (total duration >25 ns) on the E. coli outer membrane
protease OmpT embedded in a DMPC lipid bilayer show that the protein is
conformationally stable with the greatest degree of flexibility in the
extracellular loops. Some tilting of the beta-barrel is observed
relative to the bilayer plane. The active site residues form a network
of H-bonds which supports a catalytic mechanism whereby Asp83 and
His212 bind a water molecule which attacks the peptide carbonyl.
Docking calculations corroborated a possible attack by this water
molecule. The trajectories of water molecules reveal exchange of waters
between the intracellular compartment and the barrel interior but no
exchange at the extracellular mouth. This suggests that the 'pore-like'
region in the centre of OmpT may enable access of water to the active
site 'from below'. The simulations appear to reveal the presence of
specific lipid interaction sites on the surface of the OmpT barrel.