Determining the Protective Activity of IDPs Under Partial Dehydration and Freeze-Thaw Conditions.

Unlike for structured proteins, the study of intrinsically disordered proteins (IDPs) requires selection of ad hoc assays and strategies to characterize their dynamic structure and function. Late embryogenesis abundant (LEA) proteins are important plant IDPs closely related to water-deficit stress response. Diverse hypothetical functions have been proposed for LEA proteins, such as membrane stabilizers during cold stress, oxidative regulators acting as ion metal binding molecules, and protein protectants during dehydration and cold/freezing conditions. Here we present two detailed protocols to characterize IDPs with potential protein/enzyme protection activity under partial dehydration and freeze-thaw treatments.

The functional diversity of structural disorder in plant proteins.

Structural disorder in proteins is a widespread feature distributed in all domains of life, particularly abundant in eukaryotes, including plants. In these organisms, intrinsically disordered proteins (IDPs) perform a diversity of functions, participating as integrators of signaling networks, in transcriptional and post-transcriptional regulation, in metabolic control, in stress responses and in the formation of biomolecular condensates by liquid-liquid phase separation. Their roles impact the perception, propagation and control of various developmental and environmental cues, as well as the plant defense against abiotic and biotic adverse conditions. In this review, we focus on primary processes to exhibit a broad perspective of the relevance of IDPs in plant cell functions. The information here might help to incorporate this knowledge into a more dynamic view of plant cells, as well as open more questions and promote new ideas for a better understanding of plant life.

Structural disorder in plant proteins: where plasticity meets sessility.

Plants are sessile organisms. This intriguing nature provokes the question of how they survive despite the continual perturbations caused by their constantly changing environment. The large amount of knowledge accumulated to date demonstrates the fascinating dynamic and plastic mechanisms, which underpin the diverse strategies selected in plants in response to the fluctuating environment. This phenotypic plasticity requires an efficient integration of external cues to their growth and developmental programs that can only be achieved through the dynamic and interactive coordination of various signaling networks. Given the versatility of intrinsic structural disorder within proteins, this feature appears as one of the leading characters of such complex functional circuits, critical for plant adaptation and survival in their wild habitats. In this review, we present information of those intrinsically disordered proteins (IDPs) from plants for which their high level of predicted structural disorder has been correlated with a particular function, or where there is experimental evidence linking this structural feature with its protein function. Using examples of plant IDPs involved in the control of cell cycle, metabolism, hormonal signaling and regulation of gene expression, development and responses to stress, we demonstrate the critical importance of IDPs throughout the life of the plant.

Insights into the function of the phasiRNA-triggering miR1514 in response to stress in legumes.

We recently described the activity of miR1514a in response to water deficit in Phaseolus vulgaris. Pvu-miR1514a targets a NAC transcription factor mRNA for cleavage and subsequently triggers NAC-derived phasiRNA formation. Here we show that accumulation and activity of miR1514a are also conserved in the model legume Medicago truncatula. Consistently, we identified Mtr-miR1514a and detected its increased accumulation in response to stress conditions, targeting a NAC TF mRNA for cleavage and triggering phasiRNA production. In P. vulgaris, miR1514a inhibition in transgenic hairy roots was reported to increase NAC 700 mRNA levels and to affect expression patterns of several genes, including that of a Sec 14 homolog. We report here that in adult plant roots exposed to dehydration conditions, where miR1514a levels increased and NAC 700 mRNA decreased, there was a reduction of Sec 14 homolog mRNA levels, suggesting a direct transcriptional effect. The functions of miR1514a, NAC 700 and derived phasiRNAs have just begun to be elucidated in common bean; future understanding of their activities in this and other legumes species will advance our knowledge of microRNA functions in plants.