Reference "14-3-3 protein is a regulator of the mitochondrial and chloroplast ATP synthase"

Reference ID

396

Title

14-3-3 protein is a regulator of the mitochondrial and chloroplast ATP synthase

Source

Proceedings of the National Academy of Sciences of the United States of America, 2001, vol. 98, pp. 4249-4254

Authors (3)

Bunney-T-D	van_Walraven-H-S
de_Boer-A-H

Abstract

Mitochondrial and chloroplast ATP synthases are key enzymes in plant metabolism,
providing cells with ATP, the universal energy currency. ATP synthases use a
transmembrane electrochemical proton gradient to drive synthesis of ATP. The
enzyme complexes function as miniature rotary engines, ensuring energy coupling
with very high efficiency. Although our understanding of the structure and
functioning of the synthase has made enormous progress in recent years, our
understanding of regulatory mechanisms is still rather preliminary. Here we
report a role for 14-3-3 proteins in the regulation of ATP synthases. These 14-3-
3 proteins are highly conserved phosphoserine/phosphothreonine-binding proteins
that regulate a wide range of enzymes in plants, animals, and yeast. Recently,
the presence of 14-3-3 proteins in chloroplasts was illustrated, and we show
here that plant mitochondria harbor 14-3-3s within the inner mitochondrial-
membrane compartment. There, the 14-3-3 proteins were found to be associated
with the ATP synthases, in a phosphorylation-dependent manner, through direct
interaction with the F(1) beta-subunit. The activity of the ATP synthases in
both organelles is drastically reduced by recombinant 14-3-3. The rapid
reduction in chloroplast ATPase activity during dark adaptation was prevented by
a phosphopeptide containing the 14-3-3 interaction motif, demonstrating a role
for endogenous 14-3-3 in the down-regulation of the CF(o)F(1) activity. We
conclude that regulation of the ATP synthases by 14-3-3 represents a mechanism
for plant adaptation to environmental changes such as light/dark transitions,
anoxia in roots, and fluctuations in nutrient supply.