Topographical structure of membrane-bound Escherichia coli F1F0 ATP synthase in aqueous buffer.
Scanning force microscope images of membrane-bound Escherichia coli ATP synthase F0 complexes have been obtained in aqueous solution. The images show a consistent set of internal features: a ring structure which surrounds a central dimple and contains an asymmetric lateral mass. Images of trypsin-treated F0 complexes, which have lost part of their b subunits, show a reduced asymmetric mass, while images of c-subunit oligomers, which lack both the a and b subunits, show a ring and dimple but do not have an asymmetric mass. These results support models in which the F0 complex contains a ring of 9-12 c subunits with the b subunits located outside this ring, and show that scanning force microscopy is able to provide structural information on membrane proteins of molecular mass less than 200 000 Da.
Singh
S
S
Department of Chemistry, University of New Mexico, Albuquerque 87131, USA.
Turina
P
P
Bustamante
C J
CJ
Keller
D J
DJ
Capaldi
R
R
D004926:Escherichia coli / Q000201:enzymology; D007091:Image Processing, Computer-Assisted; D008567:Membranes, Artificial; D008853:Microscopy; D010714:Phosphatidylethanolamines; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000648:ultrastructure; D014357:Trypsin
D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines; D014357:Trypsin; D006180:Proton-Translocating ATPases