OsUEV1B, a Ubc Enzyme Variant Protein, Is Required for Phosphate Homeostasis in Rice

The document presents a study on the role of OsUEV1B, a ubiquitin-conjugating enzyme variant protein, in regulating phosphate (Pi) homeostasis in rice. The study found that knockdown of OsUEV1B led to Pi overaccumulation and toxicity symptoms, with increased Pi acquisition and activation of Pi starvation responses even when Pi was sufficient. This was due to the interaction between OsUEV1B and OsVDAC1, a voltage-dependent anion channel in mitochondria, which also interacted with OsUbc13. Mutations in OsVDAC1 resulted in similar Pi overaccumulation. Knockout of OsUEV1B or OsVDAC1 reduced mitochondrial membrane potential and ATP levels, with ATP levels decreasing by 11.7% in osuev1b and 33.5% in vdac1-2 mutants. Conversely, overexpression of OsVDAC1 increased ATP levels by 17.3% and partially restored Pi concentration levels in osuev1b mutants. The study concluded that OsUEV1B is essential for Pi homeostasis in rice and functions by interacting with OsVDAC1, affecting mitochondrial function and multiple Pi starvation responses. The sample size for certain measurements was three biological repeats (n = 3).