de.mpg.escidoc.pubman.appbase.FacesBean
English
 
Help Guide Disclaimer Contact us Login
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

A tetrameric porin limits the cell wall permeability of Mycobacterium smegmatis

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons77938

Engelhardt,  H.
Baumeister, Wolfgang / Molecular Structural Biology, Max Planck Institute of Biochemistry, Max Planck Society;

Locator
There are no locators available
Fulltext (public)
There are no public fulltexts available
Supplementary Material (public)
There is no public supplementary material available
Citation

Engelhardt, H., Heinz, C., & Niederweis, M. (2002). A tetrameric porin limits the cell wall permeability of Mycobacterium smegmatis. Journal of Biological Chemistry, 277(40), 37567-37572.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-6E1C-3
Abstract
Mycobacteria protect themselves with an outer lipid bilayer, which is the thickest biological membrane hitherto known and has an exceptionally low permeability rendering mycobacteria intrinsically resistant against many antibiotics. Pore proteins mediate the diffusion of hydrophilic nutrients across this membrane. Electron microscopy revealed that the outer membrane of Mycobacterium smegmatis contained about 1000 protein pores per mum(2), which are about 50-fold fewer pores per mum(2) than in Gram-negative bacteria. The projection structure of the TV or porin MspA of M. smegmatis was determined at 17 resolution. MspA forms a cone-like tetrameric complex of 10 nm in length with a single central pore. Thus, MspA is drastically different from the trimeric porins of Gram-negative bacteria and represents a new class of channel proteins. The formation of MspA micelles indicated that the ends of MspA have different hydrophobicities. Oriented insertion of MspA into membranes was demonstrated in lipid bilayer experiments, which revealed a strongly asymmetrical voltage gating of MspA channels at -30 mV. The length of MspA is sufficient to span the outer membrane and contributes in combination with the tapering end of the pore and the low number of pores to the low permeability of the cell wall of M. smegmatis for hydrophilic compounds.