In:
The FEBS Journal, Wiley, Vol. 281, No. 8 ( 2014-04), p. 2030-2041
Abstract:
The cell wall of the Gram‐positive mycolic‐acid‐containing actinomycete Dietzia maris DSM 43672 was found to contain a pore‐forming protein, as observed from reconstitution experiments with artificial lipid bilayer experiments in the presence of cell wall extracts. The cell wall porin was purified to homogeneity using different biochemical methods and had an apparent molecular mass of about 120 kD a on tricine‐containing SDS/PAGE. The 120 kD a protein dissociated into subunits with a molecular mass of about 35 kD a when it was heated to 100 °C in 8 m urea. The 120 kD a protein, here named PorA Dm , formed ion‐permeable channels in lipid bilayer membranes with a high single‐channel conductance of about 5.8 nS in 1 m KCl. Asymmetric addition of PorA Dm to lipid bilayer membranes resulted in an asymmetric voltage dependence. Zero‐current membrane potential measurements with different salt solutions suggested that the porin of D. maris is cation‐selective because of negative charges localized at the channel mouth. Analysis of the single‐channel conductance using non‐electrolytes with known hydrodynamic radii indicated that the diameter of the cell wall channel is about 2 nm. The channel characteristics of the cell wall porin of D. maris are compared with those of other members of the mycolata. They share some common features because they are composed of small molecular mass subunits and form large and water‐filled channels. The porin was subjected to protein analysis by mass spectrometry but its sequence had no significant homology to any known porin sequences.
Type of Medium:
Online Resource
ISSN:
1742-464X
,
1742-4658
DOI:
10.1111/febs.2014.281.issue-8
Language:
English
Publisher:
Wiley
Publication Date:
2014
detail.hit.zdb_id:
2172518-4
SSG:
12
