Cell surface exposure of the outer membrane cytochromes of Shewanella oneidensis MR-1.
OBJECTIVE
To determine if the outer membrane (OM) cytochromes of the metal-reducing bacterium Shewanella oneidensis MR-1 are exposed on the cell surface.


RESULTS
MR-1 cells were incubated with proteinase K or buffer and the resulting degradation of the OM cytochromes was examined by Western blotting. The periplasmic fumarate reductase (control) was not degraded. The OM cytochromes OmcA and OmcB were significantly degraded by proteinase K (71 and 31%, respectively). Immunofluorescence confirmed a prominent cell surface exposure of OmcA and a partial exposure of OmcB and the noncytochrome OM protein MtrB.


CONCLUSIONS
The cytochromes OmcA and OmcB are exposed on the outer face of the OM.


CONCLUSIONS
The cell surface exposure of these cytochromes could allow them to directly contact extracellular insoluble electron acceptors (e.g. manganese oxides) and is consistent with their in vivo role.
Myers
C R
CR
Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA. cmyers@mcw.edu
Myers
J M
JM
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins; D002462:Cell Membrane / Q000201:enzymology*; D003574:Cytochrome c Group / Q000378:metabolism*; D019286:Endopeptidase K / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D020592:Shewanella / Q000201:enzymology* / Q000254:growth & development
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003574:Cytochrome c Group; C436968:OmcB protein, bacteria; C114590:omc A protein, Shewanella putrefaciens; D019286:Endopeptidase K