title: Coupling factor F1 ATPase with defective beta subunit from a mutant of Escherichia coli.
abstract: The defective coupling factor F1 ATPase from a mutant strain (KF11) of Escherichia coli was purified to a practically homogeneous form. The final specific activity of Mg2+-ATPase was 6-9 units/mg protein, which is about 10-15 times lower than that of F1 ATPase from the wild-type strain. The mutant F1 had a ratio of Ca2+-ATPase to Mg2+-ATPase of about 3.5, whereas the wild-type F1 had ratio of about 0.8. The mutant F1 was more unstable than wild-type F1: on storage at -80 degrees C for 2 weeks, about 80% of its activity (dependent on Ca2+ or Mg2+) was lost, whereas none of the activity of the wild-type F1 was lost. The following results indicate that the mutation is in the beta subunit. (i) High Mg2+-ATPase activity (about 20 units/mg protein) was reconstituted when the beta subunit from wild type F1 was added to dissociated mutant F1 and the mixture was dialyzed against buffer containing ATP and Mg2+. (ii) Low ATPase activity having the same ratio of Ca2+-ATPase to Mg2+-ATPase as the mutant F1 was reconstituted when a mixture of the beta subunit from the mutant F1 and the alpha and gamma subunits from wild-type F1 was dialyzed against the same buffer. (iii) Tryptic peptide analysis of the beta subunit of the mutant showed a difference in a single peptide compared with the wild-type strain.
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D008274:Magnesium / Q000494:pharmacology; D009154:Mutation; D010455:Peptides / Q000032:analysis; D006180:Proton-Translocating ATPases; D014357:Trypsin
chemical_list: D010455:Peptides; D014357:Trypsin; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; D000252:Calcium-Transporting ATPases; D008274:Magnesium