|MspA is the major porin in the outer membrane of M. smegmatis mediating the exchange of hydrophilic solutes between the environment and the periplasm. (A) The MspA crystal structure reveals a homo-octameric goblet-like conformation with a single channel and constitutes the first structure of a mycobacterial outer membrane protein (1). The channel diameter varies between 4.8 nm and 1.0 nm at the pore eyelet, which is completely defined by two rings of aspartates. The biophysical properties of MspA are drastically different from the trimeric porins of Gram-negative bacteria. Its extraordinary stability permits AFM-imaging on mica or gold using the Magnetic A/C mode without the support of a (bilayer) membrane! Due to the presence of 16 aspartates in the pore eyelet, MspA can serve as stable host-system for cationic guests (ruthenium(II)-polypyridyl complexes and resorcine-arenes), leading to medicinal and nanotechnological applications. |
(1): Faller, M.; Niederweis, M.; Schulz, G. E. Science 2004, 303, 1189-1192.
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster