A 13-subunit c-ring in the Chlamydomonas chloroplast ATP synthase lowers the H⁺/ATP cost of carbon fixation
Lorencik, K.; Pintscher, S.; Richardson, K.; Takahashi, H.; Proctor, M.; Rawski, M.; Hunter, C. N.; Hitchcock, A.; Blaza, J. N.; Johnson, M. P. · biochemistry · 2026-09-06 · 原文
DOI：10.64898/2026.09.03.749062作者：10 位
The chloroplast F1Fo ATP synthase is a rotary motor that converts the light-driven proton-motive force into the chemical energy of ATP. The number of c-subunits in its rotor fixes the number of protons translocated per ATP formed, a fundamental parameter of bioenergetic systems. The reference spinach enzyme possesses fourteen c-subunits and a H+/ATP ratio of 4.67. Green algae additionally operate a carbon-concentrating mechanism that sustains CO2 fixation in water at a substantial cost in ATP, yet the structure of the algal motor, and whether its bioenergetic parameters differ from those of vascular plants, remains unresolved. Here, a 2.2 [A] structure of the ATP synthase of Chlamydomonas reinhardtii reveals that the enzyme carries a thirteen-membered c-ring, the first departure from c14 in a chloroplast, and with a lower predicted H+/ATP ratio of 4.33. Ordered waters trace a Grotthuss proton relay through the membrane, where an insulating triad separates the proton loading and unloading sites and couples flux to rotation. A single substitution in the redox switching {gamma}-subunit abolishes the contact with the catalytic {beta}-subunit that idles the enzyme in darkness in vascula
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1. 人话版
The chloroplast F1Fo ATP synthase is a rotary motor that converts the light-driven proton-motive force into the chemical energy of ATP.
The number of c-subunits in its rotor fixes the number of protons translocated per ATP formed, a fundamental parameter of bioenergetic systems.
2. 领域脉络
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3. 机制拆解
摘要未展开方法细节——精读时重点看方法/模型部分。
4. 证据与数字
The reference spinach enzyme possesses fourteen c-subunits and a H+/ATP ratio of 4.67.
Green algae additionally operate a carbon-concentrating mechanism that sustains CO2 fixation in water at a substantial cost in ATP, yet the structure of the algal motor, and whether its bioenergetic parameters differ from those of vascular plants, remains unresolved.
Here, a 2.2 [A] structure of the ATP synthase of Chlamydomonas reinhardtii reveals that the enzyme carries a thirteen-membered c-ring, the first departure from c14 in a chloroplast, and with a lower predicted H+/ATP ratio of 4.33.
5. 反例与边界
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