Disequilibrium between chloroplast proton motive force and ATP levels in Arabidopsis.

Chloroplast MgATP 2- levels remain stable despite reduced proton motive force in Arabidopsis mutants, challenging the necessity of cyclic electron transfer for ATP production.

• Why it matters: Understanding how ATP levels are maintained in plants is crucial for revealing the flexibility of photosynthetic energy regulation, especially when known pathways are disrupted.
• What they did: Researchers used the MgATP 2- fluorescent biosensor ATeam1.03-nD/nA to measure ATP and proton motive force in Arabidopsis mutants lacking PGR5 and NDH pathways, finding proton motive force reduced to 50-75% of wild type.
• The result: The findings show that ATP levels stay constant despite decreased proton motive force, suggesting cyclic electron transfer is not essential for ATP augmentation in chloroplasts.