Characterization of the purified membrane attachment (δ) subunit of the proton translocating adenosine triphosphatase from Escherichia coli

Biochemistry ◽  
1977 ◽  
Vol 16 (18) ◽  
pp. 4020-4025 ◽  
Author(s):  
Paul C. Sternweis ◽  
Jeffrey B. Smith



1978 ◽  
Vol 172 (3) ◽  
pp. 523-531 ◽  
Author(s):  
D R H Fayle ◽  
J A Downie ◽  
G B Cox ◽  
F Gibson ◽  
J Radik

Membranes from a mutant strain of Escherichia coli K12 carrying the uncD409 allele were washed in low-ionic-strength buffers in the presence or absence of the proteinase inhibitor p-aminobenzamidine. Unlike membranes from a normal strain, those from strain AN463 (uncD409) did not become proton-permeable, as judged by NADH-induced atebrinfluorescence quenching, when the membranes were washed in the absence of p-aminobenzamide. Furthermore, ATP-dependent atebrin-fluorscence quenching in such washed membranes could not be reconstituted by the addition of solubilized Mg2+-stimulated adenosine triphosphatase preparations. The examination by two-dimensional polyacrylamide-gel electrophoresis of the polypeptide composition of the washed membranes from strain AN463 (uncD409) indicated the presence of a polypeptide of similar molecular weight to the normal beta-subunit of the Mg2+-stimulated adenosine triphosphatase, but with an altered isoelectric point. Both the normal and abnormal beta-subunits were identified in membranes prepared from a partial diploid strain carrying both the unc+ and uncD409 alleles. It is concluded that the uncD gene codes for the beta-subunit of the Mg2+-stimulated adenosine triphosphatase.







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