The many facets of protein ubiquitination and degradation in plant root iron deficiency responses.

Organisms need to deal with the absolute requirement for metals, and their possible toxicity. This is achieved through an intricate network of signaling pathways integrated to ultimately fine tune iron uptake and metabolism. The mechanisms by which plants cope with iron limitation and the associated genomic responses are well characterized. On top of this transcriptional cascade is layered another level of regulation involving the post-translational modification and degradation. The ubiquitination and/or degradation of several transcription factors in the iron deficiency signaling pathways and metal transporters recently came to light. In this review we discuss about the mechanisms and on the possible roles of protein modification and turn over in the regulation of root iron deficiency responses. We also highlight the tight coupling between metal sensing by E3 ubiquitin ligases or bifunctional transporters and protein degradation.