Atp10p Assists Assembly of Atp6p into the F0 Unit of the Yeast Mitochondrial ATPase

Abstract

The F 0 F 1 -ATPase complex of yeast mitochondria contains three mitochondrial and at least 17 nuclear gene products. The coordinate assembly of mitochondrial and cytosolic translation products relies on chaperones and specific factors that stabilize the pools of some unassembled subunits. Atp10p was identified as a mitochondrial inner membrane component necessary for the biogenesis of the hydrophobic F 0 sector of the ATPase. Here we show that, following its synthesis on mitochondrial ribosomes, subunit 6 of the ATPase (Atp6p) can be cross-linked to Atp10p. This interaction is required for the integration of Atp6p into a partially assembled subcomplex of the ATPase. Pulse labeling and chase of mitochondrial translation products in vivo indicate that Atp6p is less stable and more rapidly degraded in an atp10 null mutant than in wild type. Based on these observations, we propose Atp10p to be an Atp6p-specific chaperone that facilitates the incorporation of Atp6p into an intermediate subcomplex of ATPase subunits.

Assembly of the Rotor Component of Yeast Mitochondrial ATP Synthase Is Enhanced When Atp9p Is Supplied by Atp9p-Cox6p Complexes

“…Mitochondrial translation was enhanced by a factor of 2-3 after derepression. As reported previously, incubation of cells in chloramphenicol is especially effective in stimulating translation of Atp9p (28). This was also true of cells derepressed in medium containing chloramphenicol (Fig.…”

“…The chloramphenicol treatment was included to increase the pools of nuclear gene products of ATP synthase (28). Mitochondria were labeled with a mixture of [ 35 S]methionine and [ 35 S]cysteine (3000 Ci/mmol, MP Biochemicals) as described previously (4).…”

Defining the impact on yeast ATP synthase of two pathogenic human mitochondrial DNA mutations, T9185C and T9191C

“…In this respect, it is to be noted that the C-terminal region of Atp6p seems to be critical for interaction with Atp10p [46], an accessory protein that helps insertion of Atp6p into ATP synthase either directly or by protecting it against proteolytic degradation until it is assembled [47]. Nearly identical defects were found in a yeast model of the pathogenic mutation T9176G mutation, which changes the highly conserved leucine 217 (247 in yeast) into arginine [14].…”

The product of uncI gene in F 1 F o -ATP synthase operon plays a chaperone-like role to assist c -ring assembly

“…5). In mitochondrial F 1 F o , some proteins, such as yeast ATP10 (31,32), ATP23 (33,34), and OXA1 (35), have been shown to play a chaperonelike role to assist F o assembly, although the detailed mechanism is not well understood. Although there is no sequence homology to eukaryotic proteins, UncI protein also plays a chaperone-like role; it associates with monomers of c-subunit, assists ring assembly, and dissociates from the assembled c-ring.…”