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Molecular dynamics simulations of a bacterial autotransporter: NalP from Neisseria meningitidis

Record type: Article

NalP is an autotransporter secretory protein found in the outer membrane of Neisseria meningitidis. The crystal structure of the NalP translocator domain revealed a transmembrane ?-barrel containing a central -helix. The role of this -helix, and of the conformational dynamics of the ?-barrel pore have been studied via atomistic molecular dynamics simulations. Three simulations, each of 10 ns duration, of NalP embedded within a solvated DMPC bilayer were performed. The helix was removed from the barrel interior in one simulation. The conformational stability of the protein is similar to that of other outer membrane proteins, e.g., OmpA, in comparable simulations. The transmembrane ?-barrel is stable even in the absence of the -helix. Removal of the helix results in an influx of water into the pore region, suggesting the helix acts as a 'plug'. Water molecules entering the resultant pore form hydrogen bonds with the barrel lining that compensate for the loss of helix-barrel hydrogen bonds. The dimensions of the pore fluctuate over the course of the simulation revealing it to be flexible, but only wide enough to allow transport of the passenger domain in an unfolded or extended conformation. The simulations help us to understand the role of the central helix in plugging the pore and in maintaining the width of the barrel, and show that the NalP monomer is sufficient for the transport of the passenger domain in an unfolded or extended conformation.

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Citation

Khalid, Syma and Samsom, Mark S.P. (2006) Molecular dynamics simulations of a bacterial autotransporter: NalP from Neisseria meningitidis Molecular Membrane Biology, 23, (6), pp. 499-508. (doi:10.1080/09687860600849531).

More information

Published date: November 2006
Keywords: autotransporter, molecular dynamics, outer membrane protein
Organisations: Chemistry

Identifiers

Local EPrints ID: 48164
URI: http://eprints.soton.ac.uk/id/eprint/48164
ISSN: 0968-7688
PURE UUID: 589db0aa-f937-447e-817b-ebfa6fa22f2e

Catalogue record

Date deposited: 31 Aug 2007
Last modified: 17 Jul 2017 15:00

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Contributors

Author: Syma Khalid
Author: Mark S.P. Samsom

University divisions


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