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Query: UNIPROT:P62988 (Ubiquitin)
 4,326 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ubiquitin-mediated proteolysis is an integral part of diverse cellular functions, and of the three enzymes involved in linking ubiquitin to protein targets, the E3 ubiquitin ligases are of particular interest as they confer substrate specificity during this process. The E3 ubiquitin ligases can be categorized based on mechanism of action and on the presence of specific domains such as RING, HECT, F-box, and U-box. In plants, the U-box family has undergone a large gene expansion that may be attributable to biological processes unique to the plant life cycle. For example, there are 64 predicted plant U-box (PUB) proteins in Arabidopsis, and the biological roles of many of these have yet to be determined. Research on PUB genes from several different plants has started to elucidate a range of functions for this family, from self-incompatibility and hormone responses to defence and abiotic stress responses. Expression profiling has also been used as a starting point to elucidate PUB function, and has uncovered a strong connection of PUB genes to various stress responses. Finally, some PUB proteins have been linked to receptor kinases as upstream activators, and downstream target substrates are also starting to emerge. The mechanisms of action range from the observation of mono-ubiquitination during non-proteolytic signalling to directed regulation of proteasomal components during stress responses, and cell death appears to be a theme underlying many PUB functions.
J Exp Bot 2009
PMID:The diversity of plant U-box E3 ubiquitin ligases: from upstream activators to downstream target substrates. 1919 49

Meristematic activity in the bud meristem of Abies nordmanniana was visualized by ubiquitin immunohistochemical localization from before bud break and throughout shoot expansion. Ubiquitin was detected in meristematic cells either in the cytosol or nucleus, or both, depending on tissue type and developmental stage. During winter dormancy, ubiquitin was only observed in the protodermal/hypodermal layers, but at bud break in mid May, the signal expanded to the entire shoot tip. At the end of May, a clear zonation in ubiquitin localization appeared that lasted about one month. Throughout this period, ubiquitin was barely detectable in a central group of cells that might indicate an organizing center with stem cells. At the end of June, coinciding with the transition from scale leaf to needle primordia production, ubiquitin again was more prevalent in the peripheral cell layers. During shoot expansion, a strong ubiquitin signal developed in the axil of all needles. Most of these signals later disappeared, except for those few axils where buds actually developed. A strong ubiquitin signal was also observed in cells lining the young resin ducts. Our data showed that ubiquitin may be used as a marker for metabolic activity associated with seasonal development in the apical meristem.
Am J Bot 2008 Jun
PMID:Ontogeny in terminal buds of Abies nordmanniana (Pinaceae) characterized by ubiquitin. 2163 2

Heterotrimeric nuclear factors Y (NF-Ys) are involved in regulation of various vital functions in all eukaryotic organisms. Although a number of NF-Y subunits have been characterized in model plants, only a few have been functionally evaluated in crops. In this work, a number of genes encoding NF-YB and NF-YC subunits were isolated from drought-tolerant wheat (Triticum aestivum L. cv. RAC875), and the impact of the overexpression of TaNF-YB4 in the Australian wheat cultivar Gladius was investigated. TaNF-YB4 was isolated as a result of two consecutive yeast two-hybrid (Y2H) screens, where ZmNF-YB2a was used as a starting bait. A new NF-YC subunit, designated TaNF-YC15, was isolated in the first Y2H screen and used as bait in a second screen, which identified two wheat NF-YB subunits, TaNF-YB2 and TaNF-YB4. Three-dimensional modelling of a TaNF-YB2/TaNF-YC15 dimer revealed structural determinants that may underlie interaction selectivity. The TaNF-YB4 gene was placed under the control of the strong constitutive polyubiquitin promoter from maize and introduced into wheat by biolistic bombardment. The growth and yield components of several independent transgenic lines with up-regulated levels of TaNF-YB4 were evaluated under well-watered conditions (T1-T3 generations) and under mild drought (T2 generation). Analysis of T2 plants was performed in large deep containers in conditions close to field trials. Under optimal watering conditions, transgenic wheat plants produced significantly more spikes but other yield components did not change. This resulted in a 20-30% increased grain yield compared with untransformed control plants. Under water-limited conditions transgenic lines maintained parity in yield performance.
J Exp Bot 2015 Nov
PMID:Constitutive overexpression of the TaNF-YB4 gene in transgenic wheat significantly improves grain yield. 2622 82

Plants can be simultaneously exposed to multiple stresses. The interplay of abiotic and biotic stresses may result in synergistic or antagonistic effects on plant development and health. Temporary drought stress can stimulate plant immunity; however, the molecular mechanism of drought-induced immunity is largely unknown. In this study, we demonstrate that cysteine protease RD21A is required for drought-induced immunity. Temporarily drought-treated wild-type Arabidopsis plants became more sensitive to the bacterial pathogen-associated molecular pattern flg22, triggering stomatal closure, which resulted in increased resistance to Pseudomonas syringae pv. tomato DC3000 (Pst-DC3000). Knocking out rd21a inhibited flg22-triggered stomatal closure and compromised the drought-induced immunity. Ubiquitin E3 ligase SINAT4 interacted with RD21A and promoted its degradation in vivo. The overexpression of SINAT4 also consistently compromised the drought-induced immunity to Pst-DC3000. A bacterial type III effector, AvrRxo1, interacted with both SINAT4 and RD21A, enhancing SINAT4 activity and promoting the degradation of RD21A in vivo. Therefore, RD21A could be a positive regulator of drought-induced immunity, which could be targeted by pathogen virulence effectors during pathogenesis.
J Exp Bot 2020 Sep 19
PMID:Cysteine protease RD21A regulated by E3 ligase SINAT4 is required for drought-induced resistance to Pseudomonas syringae in Arabidopsis. 3245 12

Rice is a major dietary source of the toxic metal cadmium (Cd), and reducing its accumulation in the grain is therefore important for food safety. We selected two cultivars with contrasting Cd accumulation and generated transgenic lines overexpressing OsNRAMP5, which encodes a major influx transporter for manganese (Mn) and Cd. We used two different promoters to control the expression, namely OsActin1 and maize Ubiquitin. Overexpression of OsNRAMP5 increased Cd and Mn uptake into the roots, but markedly decreased Cd accumulation in the shoots, whilst having a relatively small effect on Mn accumulation in the shoots. The overexpressed OsNRAMP5 protein was localized to the plasma membrane of all cell types in the root tips and lateral root primordia without polarity. Synchrotron X-ray fluorescence mapping showed that the overexpression lines accumulated more Cd in the root tips and lateral root primordia compared with the wild-type. When grown in three Cd-contaminated paddy soils, overexpression of OsNRAMP5 decreased concentration of Cd in the grain by 49-94% compared with the wild type. OsNRAMP5-overexpression plants had decreased Cd translocation from roots to shoots as a result of disruption of its radial transport into the stele for xylem loading, demonstrating the effect of transporter localization and polarity on ion homeostasis.
J Exp Bot 2020 Sep 19
PMID:Overexpression of the manganese/cadmium transporter OsNRAMP5 reduces cadmium accumulation in rice grain. 3254 48