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- Title
The cell wall of Micromonospora purpurea contains a high conductance channel.
- Authors
Kim, Bong-Hui; Wengerter, Karin; Benz, Roland
- Abstract
In this communication it is demonstrated that the cell wall of the gram-positive bacterium Micromonospora purpurea contains a cell wall channel for the passage of hydrophilic solutes. The channel-forming protein was identified in sucrose step-density-gradient fractions of the cell envelope and in whole cell extracts using either organic solvent or detergent and the lipid bilayer technique. The fractions of the sucrose step-density centrifugation were assayed for NADH-oxidase activity and for the formation of ion-permeable channels in lipid bilayers. The highest NADH-oxidase activity and the highest channel-forming ability were found in different fractions. The cell wall fraction was identified by the presence of meso-diaminopimelic acid and contained an ion-permeable channel with the extremely high single-channel conductance of about 14 nS in 1 M KCl. The channel-forming unit was purified to homogeneity by FPLC on a HiTrap-Q column. It was identified as a heat- and SDS-resistant 200-kDa band on SDS-PAGE and formed the same general diffusion pores in lipid bilayer membranes as those formed by detergent extracts of the cell wall fraction of the sucrose step-density centrifugation. The channels were slightly selective for potassium ions over chloride, possibly caused by an excess of negative charges in or near the channel.
- Subjects
BACTERIAL cell walls; GRAM-positive bacteria; MICROMONOSPORA; PROTEINS; SUCROSE; LIPIDS
- Publication
Archives of Microbiology, 2002, Vol 177, Issue 2, p184
- ISSN
0302-8933
- Publication type
Article
- DOI
10.1007/s00203-001-0376-0