TY  - JOUR
A1  - Hoppe, J.
A1  - Friedl, P.
A1  - Schairer, H. U.
A1  - Sebald, Walter
A1  - Meyenburg, K. von
A1  - Jorgensen, B. B.
T1  - The topology of the proton translocating F\(_0\) component of the ATP synthase from E. coli K12: studies with proteases
N2  - The accessibility of the three F\(_0\) subunits a, b and c from the Escherichia coli Kll A TP synthase to various proteases was studied in F\(_1\)-depleted inverted membrane vesicles. Subunit b was very sensitive to all applied proteases. Chymotrypsin produced a defined fragment of mol. wt. 1S 000 which remained tightly bound to the membrane. The cleavage site was located at the C-terminal region of subunit b. Larger amounts of proteases were necessary to attack subunit a (mol. wt. 30 000). There was no detectable deavage of subunit c. It is suggested that the major hydrophilic part of subunit b extends from the membrane into the cytoplasm and is in contact with the F\(_1\) sector. The F\(_1\) sector was found to afford some protection against proteolysis oftheb subunit in vitro andin vivo. Protease digestion bad no influence on the electro-impelled H\(^+\) conduction via F\(_0\) bot ATP-dependent H\(^+\) translocation could not be reconstituted upon binding of F\(_1\)• A possible role for subunit b as a linker between catalytic events on the F\(_1\) component and the proton pathway across the membrane is discussed.
KW  - Biochemie
KW  - protein pathway
KW  - ATPase mutants
Y1  - 1983
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-62718
ER  - 
TY  - JOUR
A1  - Schairer, H. U.
A1  - Hoppe, J.
A1  - Sebald, Walter
A1  - Friedl, P.
T1  - Topological and functional aspects of the proton conductor, F\(_0\), of the Escherichia coli ATP-synthase
N2  - The isolated H\(^+\) conductor, F\(_0\) , of the Escherichia co1i ATP-synthase consists of three subunits, a, b, and c. H\(^+\) -permeable liposomes can be reconstit~ted with F\(_0\) and lipids; addition of F\(_1\)-ATPase reconstitutes a functional ATP-synthase. Mutants with altered or misslng F\(_0\) subunits are defective in H\(^+\) conduction. Thus, all three subunits are necessary for the expression of H\(^+\) conduction. The subunits a and b contain binding sites for F\(_1\)• Computer calculations, cross-links, membrane-permeating photo-reactive labels, and proteases were used to develop tentative structural models for the individual F\(_0\) subunits.
KW  - Biochemie
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-62721
ER  - 
TY  - JOUR
A1  - Sebald, Walter
A1  - Friedl, P.
A1  - Schairer, H. U.
A1  - Hoppe, J.
T1  - Structure and genetics of the H\(^+\)-conducting F\(_0\) portion of the ATP synthase
N2  - The ATP synthase occurs in remarkably conserved form in procaryotic and eucaryotic cells. Thus, our present knowledge of ATP synthase is derived from sturlies of the enzyme from different organisms, each affering specific experimental possibilities. In recent tim es, research on the H\(^+\) -conducting F0 part of the ATP synthase has been greatly stimulated by two developments in the Escherichio coli system. Firstly, the purification and reconstitution of the whole ATP synthase as weil as the proton conductor Fa from E. coli have been achieved. These functionally active preparations are well defined in terms of subunit composition, similar to the thermophilic enzyme from PS-3 studied by Kagawa's group.u Secondly, the genetics and the molecular cloning of the genes of all the F\(_0\) subunits from E. coli yielded information on the function of subunit polypeptides and essential amino acid residues. Furthermore, the amino acid sequence of hydrophobic F\(_0\) subunits, which are difficult to analyze by protein-chemical techniques, could be derived from the nucleotide sequence of the genes. These achievements, which shall be briefly summarized in the next part of this communication, provide the framework to study specific aspects of the structure and function of the F\(_0\) subunits.
KW  - Biochemie
Y1  - 1982
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-62733
ER  -