Atomic-force-studies of the Porin MspA from M. smegmatis on mica and gold surfaces

PHYS 483

Stefan H. Bossmann, sbossman@ksu.edu1, Matthew Basel1, and Michael Niederweis, mnieder@uab.edu2. (1) Department of Chemistry, Kansas State University, 111 Willard Hall, Manhattan, KS 66506-3701, (2) Department of Microbiology, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2710
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.

 

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

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Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006