Subunit equivalence in Escherichia coli and bovine heart mitochondrial F₁F₀ ATPases

Abstract

F1‐ATPases from bovine mitochondria and Escherichia coli both contain 5 subunits named α, β, γ, δ and ε. Sequence analysis shows that the δ subunits are not related, nor are the ε subunits. The counterpart of mitochondrial δ is bacterial ε. The subunit equivalent to bacterial δ is mitochondrial oligomycin sensitivity conferral protein.

Lack of ability of trypsin‐treated mitochondrial F1‐ATPase to bind the oligomycin‐sensitivity conferring protein (OSCP)

“…Such a functional similarity would be in accordance with recent data on the primary structure of beef-heart OSCP [26] which have revealed a striking homology with the S-subunit of E. coli Fr [15]. Whether the two polypeptides bind directly to the cu-subunit of Ft, or whether the failure of trypsin-modified Ft to bind them is a secondary consequence of a modification of the quaternary structure of the enzyme as a whole, remains to be elucidated.…”

Amino acid sequence of the oligomycin sensitivity‐conferring protein (OSCP) of beef‐heart mitochondria and its homology with the δ‐subunit of the F1‐ATPase of Escherichia coli

“…For a number of years it was generally believed that OSCP has no counterpart in chloroplasts and bacteria. Recently, however, determination of the N-and C-terminal sequences of beef-heart OSCP [3] has revealed a homology [4] between this protein and the d-subunit of E. colt' Fr [S]. These findings were paralleled by observations [6,7] suggesting a functional similarity between the two proteins.…”

“…Comparative analysis of the complete amino acid sequences of OSCP and &subunit of Fl of E. coli ATPase (fig.2) reveals a considerable struc- tural homology not only in C-and N-terminal regions of their molecules [3,4] but also in the central part. These data and available information on a functional similarity between OSCP and 6-subunit [6,7] suggest that OSCP is a real counterpart of the E. coli J-subunit.…”

Cross‐reconstitution studies with polypeptides of Escherichia coli and bovine heart mitochondrial FoF1 ATP synthase

“…Additional support for this conclusion is derived from comparison of binding capacities of USMP and UP,, for F, (Fig. 1) [50, 511. In the mitochondrial F,F, ATP synthase, the F, subunits F,,I-PVP (proposed to be analogous to subunit b of E. coli 152, 53]), OSCP (suggested to bear partial similarity to subunits S and b of E. coli 129, [54][55][56][57]) and the F, protein (which has no obvious counterpart in the E. coli enzyme) are required for interaction with F, 1221. The present studies show that isolated mitochondrial FJPVP protein, OSCP and the F, protein had no effect on the USMP+ECF, and USMP+BHF, systems (obviously due to the presence of all three proteins in USMP 1191; data not shown) but produced significant effects on the ATP-hydrolase activity when added to UP,,+EcF, or UP,,+BHF,.…”