Group leader: L. Maria Lois

Research project:

Cellular reprograming by nucleocytoplasmic partitioning of SUMO conjugation to proteins.

Subcellular localization is one of the main determinants of protein function and, consequently, influences cell physiology (Orre et al, 2019). The capacity of some proteins to shuttle between the nucleus and the cytosol adds another regulatory layer to bring precision to protein activity. In plants, nucleocytoplasmic partitioning regulates a wide array of signaling pathways, including phytohormones, environmental challenges, and pathogen responses (Allen & Strader, 2021). Protein activity is also regulated by post-translational modifications, such as SUMO conjugation or SUMOylation, which is essential and mediates plant adaptation to environmental challenges. In the plant model Arabidopsis, several studies point to a nuclear enrichment of the SUMOylation machinery (Benlloch & Lois, 2018; Morrell & Sadanandom, 2019), which is consistent with a prominent accumulation of SUMO targets in the nucleus (Miller et al, 2010). Nonetheless, non–nuclear targets are quantitatively important (Rytz et al, 2018) and the molecular mechanisms that mediate their modification remain elusive.

We have uncovered a molecular mechanism based on SUMO E1 cytosolic shuttling that promotes accumulation of cytosolic SUMO conjugates. We hypothesize that increasing cytosolic SUMOylation constitutes a growth arrest signal based on the following observations: the cytosolic enrichment of SUMO E1 is concomitant to embryo growth arrest and, plants expressing cytosolic variants of SUMO E1 display growth defects and are impaired in salt tolerance during germination. The extend of these alterations are related to the amount of cytosolic SUMO E1.

The general goal of the proposed project is to understand the signaling network driving (input) cytosolic SUMOylation and the cell processes responsive to cytosolic SUMOylation (output). We propose that this regulatory mechanism could be involved in seed appearance in evolution.

Key publication

https://www.frontiersin.org/articles/10.3389/fcell.2021.703795/full

Potential collaborations with other research groups

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