Abstract
Atp11p and Atp12p are members of two chaperone families essential for assembly of the mitochondrial ATP synthase in Saccharomyces cerevisiae and Homo sapiens. However, the role of their homologs in higher plants is unclear with regard to the assembly of both chloroplast ATP synthase (cpATPase) and mitochondrial ATP synthase (mtATPase). Here, we show that loss of either Atp11 or Atp12 is lethal in Arabidopsis. While Atp12 is only localized in mitochondria, Atp11 is present both in chloroplasts and mitochondria. Yeast two-hybrid analyses showed that, as their homologs in yeast, Atp11 specifically interacts with the β subunit of the mtATPase and cpATPase, and Atp12 interacts with the α subunit of the mtATPase, implying that Atp11 and Atp12 fulfill a conserved task during assembly of ATP synthase. However, the binding sites for Atp11 in the β subunit of mtATPase and cpATPase are slightly different, suggesting that the mechanisms of action may have evolved in different ways. Although Atp11 interacts with cpATPase β subunit as the two assembly factors BFA3 and BFA1, they bind to different sites of the β subunit. These results indicate that Atp11 is involved in the assembly of both cpATPase and mtATPase but Atp12 is specifically required for the assembly of mtATPase in higher plants.
Highlights
Adenosine triphosphate (ATP) is the major cellular energy storage compound used to drive numerous biochemical reactions in biological systems
The ratio of wild type to heterozygous plants in the progeny of both atp11 and atp12 heterozygous is close to 1:2 (Supplementary Table S2). These results indicate that the atp11 and atp12 mutants and their corresponding T-DNA insertion are inherited in a Mendelian manner
Subsequent analyses revealed that Atp11p and Atp12p are essential for assembly of mtATPase by binding to the β and α subunits, respectively (Wang and Ackerman, 2000; Wang et al, 2000; Ackerman and Tzagoloff, 2005), and their function is conserved during mtATPase assembly from yeast to humans (Wang et al, 2001; Ackerman, 2002)
Summary
Adenosine triphosphate (ATP) is the major cellular energy storage compound used to drive numerous biochemical reactions in biological systems. F-type ATP synthase is a multiprotein complex widely distributed in bacteria, mitochondria (mtATPase) and chloroplasts (cpATPase) (Bertoni, 2018). These enzymes share a similar structure composed of two rotary motors with distinct functionalities. The γ/ε stalk is inserted into the α3β3 hexamer and fixed on the c-ring of Fo. During ATP synthesis, the transmembrane electrochemical proton gradient generated by photosynthetic or mitochondrial electron transport drives the rotation of the c-ring and the γ/ε stalk, thereby inducing conformational changes in the catalytic sites of the α3β3 hexamer that lead to synthesis of ATP from ADP and inorganic phosphate (Junge and Nelson, 2015; Kühlbrandt, 2019)
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