Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

SUG1 is an integral component of the 26 S proteasome. Belonging to a novel putative ATPase family, it shares four conserved motifs characteristic of ATP-dependent DNA/RNA helicases. Recombinant rat SUG1 (rSUG1) produced in Escherichia coli was highly purified and characterized in terms of its biochemical properties. The rSUG1 exhibited a Mg2+-dependent ATPase activity. The Km for ATP and Vmax of rSUG1 were 35 microM and 7 pmol of ATP/min/microg of protein, respectively. Both ATPase activity to release [32P]monophosphate and [32P]ATP-labeling activity were coordinately affected by cold ATP severely, GTP and UTP moderately, and CTP little. Interestingly, the rSUG1 ATPase activity was stimulated by poly(U) and poly(C), but not by poly(A), poly(G), or by any forms of DNAs tested. A UV cross-linking assay also indicated poly(U)- and poly(C)-stimulated labeling of rSUG1 with [alpha-32P]ATP. Moreover, the ATPase activity was facilitated by cellular poly(A)+ RNA, but not by poly(A)- RNA. RNA transcribed in vitro from cDNA encoding a b-Zip protein could stimulate the ATPase activity. This is the first report to demonstrate a specific RNA requirement for ATPase with respect to the proteasomal ATPases. Our present work suggests that SUG1 can specifically interact with protein-coding RNA (mRNA) and play some roles in mRNA metabolism.
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PMID:SUG1, a component of the 26 S proteasome, is an ATPase stimulated by specific RNAs. 928 26

Summary Virus-induced gene silencing (VIGS) is an extremely powerful tool for plant functional genomics. We used Tobacco rattle virus (TRV)-derived VIGS vectors expressed from binary vectors within Agrobacterium to induce RNA silencing in plants. Leaf infiltration is the most common method of agroinoculation used for VIGS but this method has limitations as it is laborious for large-scale screening and some plants are difficult to infiltrate. Here we have developed a novel and simple method of agroinoculation, called 'agrodrench', where soil adjacent to the plant root is drenched with an Agrobacterium suspension carrying the TRV-derived VIGS vectors. By agrodrench we successfully silenced the expression of phytoene desaturase (PDS), a 20S proteasome subunit (PB7) or Mg-protoporphyrin chelatase (Chl H) encoding genes in Nicotiana benthamiana and in economically important crops such as tomato, pepper, tobacco, potato, and Petunia, all belonging to the Solanaceae family. An important aspect of agrodrench is that it can be used for VIGS in very young seedlings, something not possible by the leaf infiltration method, which usually requires multiple fully expanded leaves for infiltration. We also demonstrated that VIGS functioned to silence target genes in plant roots. The agrodrench method of agroinoculation was more efficient than the leaf infiltration method for VIGS in roots. Agrodrench will facilitate rapid large-scale functional analysis of cDNA libraries and can also be applied to plants that are not currently amenable to VIGS technology by conventional inoculation methods.
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PMID:Agrodrench: a novel and effective agroinoculation method for virus-induced gene silencing in roots and diverse Solanaceous species. 1544 57

Leaf senescence is characterized by nitrogen remobilization to developing seeds of annual plants, or surviving organs of perennial species. It has been demonstrated that high carbohydrate levels (carbon "feast") are associated with the onset of the senescence process. Therefore, the development of model systems allowing the manipulation of leaf carbohydrates constitutes a logical first step in the investigation of processes important during early phases of senescence, such as plastidial protein degradation. In this study, sugar accumulation was induced either by the incubation of excised, mature barley (Hordeum vulgare L.) leaves under relatively strong light, or by the interruption of sieve tubes at the base of the leaf lamina by "steam-girdling". Accelerated chlorophyll degradation and net proteolysis confirmed successful senescence induction in both model systems, but suggested that girdled leaves are more useful than excised leaves to study proteolysis. Activities or transcript levels of several proteolytic enzymes, including plastidial (aminopeptidases, Clp protease), cytosolic (proteasome) and vacuolar (thiol proteases, an aspartic protease and a serine carboxypeptidase) proteases were clearly induced under these conditions; some of these genes also reacted to other stimuli such as leaf excision. The most interesting finding was the specific induction of a carboxypeptidase gene (cp-mIII) in girdled leaves accumulating high carbohydrate levels. As a previous study from our laboratory, using a genetic approach, has indicated that one or several carboxypeptidases are involved in leaf N remobilization, the detailed characterization of cp-mIII (and, possibly, closely related genes) may considerably improve our understanding of whole-plant N recycling.
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PMID:Senescence is accelerated, and several proteases are induced by carbon "feast" conditions in barley (Hordeum vulgare L.) leaves. 1603 94

Leaf morphogenesis requires the establishment of adaxial-abaxial polarity after primordium initiation from the shoot apical meristem (SAM). Several families of transcription factors are known to play critical roles in promoting adaxial or abaxial leaf fate. Recently, post-transcriptional gene silencing pathways have been shown to regulate the establishment of leaf polarity, providing novel and exciting insights into leaf development. For example, microRNAs (miR165/166) and a trans-acting siRNA (TAS3-derived tasiR-ARF) have been shown to repress the expression of several key transcription factor genes. In addition, yet another level of regulation, post-translational regulation, has been revealed recently by studies on the role of the 26S proteasome in leaf polarity. Although our understanding regarding the molecular mechanisms underlying establishment of adaxial-abaxial polarity has greatly improved, there is still much that remains elusive. This review aims to discuss recent progress, as well as the remaining questions, regarding the molecular mechanisms underlying leaf polarity formation.
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PMID:Transcriptional, post-transcriptional and post-translational regulations of gene expression during leaf polarity formation. 1754 70

Spinal cord injury and regeneration involves transcriptional activity of many genes, of which many remain unknown. Using the rat spinal cord full- transection model, bioinformatics, cloning, expression assays, fusion proteins, and transfection techniques, we identified and characterized one such differentially expressed gene, termed scirr1 (spinal cord injury and/or regeneration related gene 1). Fourteen orthologs were found in 13 species from echinoderm to insect and human by Blast search of NCBI protein reference sequence database. However, no further information is available for these homologues. Using whole-mount in situ hybridization, mouse scirr1 mRNA was expressed temporally and spatially in accordance with the early development sequence of the central nervous system. In adult rat spinal cord, expression of scirr1 mRNA was localized to neurons of gray matter by in situ hybridization. Using immunohistochemistry, SCIRR1 protein was found to be up-regulated and expressed more highly in spinal cord neurons farther from the epicenter of injury. Although the precise function of SCIRR1 is unknown, its unique pattern of expression during CNS early development and up-regulation after spinal cord injury suggest that SCIRR1 should be involved in the succeeding injury and/or repair processes of the injured spinal cord. Also, the typical F-box and leucine-rich repeat (LRR) architecture of rat SCIRR1 indicated that it may play an important substrate recruiting role in the pleiotropic ubiquitin/proteasome pathway. All these make scirr1 a new interesting start to study the spinal cord injury and regeneration mechanism.
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PMID:Identification and characterization of scirr1, a novel gene up-regulated after spinal cord injury. 1760 80

The accumulation and aggregation of fragments of amyloid precursor protein (APP) are central to the development of Alzheimer's disease. The production of the small fragment C99 is thought to form the rate-limiting step in the APP processing pathway, which can lead to the production of the toxic Abeta peptide. It has also been suggested that the proteasome contributes to APP catabolism. While the identities and aggregation propensities of many APP fragments have been studied in vitro, the sequences, structures, and cellular sources of fragments generated in vivo remains poorly elucidated. To better identify the specific APP fragments generated in vivo and to elucidate the role of the proteasome in APP processing, we developed a C99 yeast expression system. Using Zip Tip immunocapture, a specific anti-Abeta antiserum (6E10), and matrix-assisted laser desorption ionization- time of flight mass spectrometry, we identified over one dozen APP-generated peptide fragments in wild-type yeast (PRE1PRE2) and over three dozen unique fragments in proteasome mutant cells (pre1- 1pre2-1) expressing C99. Based on the identities of the immunocaptured species, we propose that defects in proteasome function are compensated by other proteases and that the combination of techniques described here will be invaluable to further delineate the APP processing pathway in vivo.
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PMID:Proteomic analysis of the amyloid precursor protein fragment C99: expression in yeast. 1786 11

The proteasome has an essential function in the intracellular degradation of protein in eukaryotic cells. We found that the dimeric quinone reductase Lot6 uses the flavin mononucleotide (FMN)-binding site to bind to the 20S proteasome with a 1:2 stoichiometry-that is, one 20S proteasome molecule can associate with two quinone reductases. Furthermore, reduction of the FMN cofactor by either NADH or light irradiation results in the binding of the b-Zip transcription factor Yap4 to the Lot6-proteasome complex, indicating that recruitment of the transcription factor depends on the redox state of the quinone reductase. Here, we show that binding of Yap4 to the complex not only protects it from ubiquitin-independent proteasomal degradation, but also regulates its cellular localization. In non-stressed wild-type cells, we did not detect any Yap4 in the nucleus, whereas Yap4 was present in the nuclei from quinone-stressed yeast cultures. Thus, the Lot6-proteasome complex can be regarded as a redox switch in which the quinone reductase acts as a sensor for oxidative stress.
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PMID:Quinone reductase acts as a redox switch of the 20S yeast proteasome. 1902 46

Leaf morphogenesis requires the establishment of adaxial-abaxial polarity in emerging leaf primordia, and a number of genes participating in this process have been identified in recent years. We previously reported that the 26S proteasome is important in specifying the leaf adaxial fate. More recently, two papers from separate researches showed that several genes encoding ribosomal large subunit proteins also play an important role in leaf adaxial-abaxial patterning. Here we show that plants with a single mutation in the genes encoding either 26S proteasome subunits or ribosomal proteins shared similar abnormalities in some leaves, with an outgrowth formed on the distal part of the leaf abaxial side. Plants harboring these 26S proteasome or ribosome mutations in combination with an additional mutation asymmetric leaves1 or 2 (as1 or as2) demonstrated severely defective leaves, and the phenotypes of these double mutants were very similar. Because activities of the 26S proteasome and ribosome both affect the level of functional proteins, the recent findings suggest that a previously unrecognized regulation, the protein level regulation, is critical in normal leaf patterning. A regulatory model for the 26S proteasome and ribosome actions in leaf patterning is discussed.
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PMID:A model for the 26S proteasome and ribosome actions in leaf polarity formation. 1970 63

Leaf organogenesis occurs within the peripheral zone of the shoot apical meristem (SAM). It has been known that several members of the class-1 KNOTTED1-like homeobox (KNOX) genes are expressed in the SAM, and their expression must be prevented during leaf primordium initiation and subsequent leaf development. A number of regulators that repress class-1 KNOX genes have been identified, and characterizations of these regulators greatly improved our knowledge of the genetic basis of leaf organogenesis. We have recently reported that the proteolytic function of the Arabidopsis 26S proteasome is involved in specifying leaf adaxial identity during leaf development, by characterizations of mutants defective in genes encoding several 26S proteasome subunits. Here we demonstrate that in addition to the role in leaf polarity establishment, the 26S proteasome also participates in repression of class-1 KNOX genes during leaf development. We show that loss of functions in RPN8a and RPT2a, two 26S proteasome subunit genes, resulted in leaves that produce ectopic outgrowths on the abaxial side of blades. These outgrowths were accompanied by the ectopic expression of several class-1 KNOX genes. These results indicate that the 26S proteasome is important in repressing class-1 KNOX genes and its function may be required until later leaf developmental stages.
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PMID:A Novel Function of the 26S Proteasome in Repressing Class-1 KNOX Genes During Leaf Development. 1970 3

In this study, the cDNA library of Chang-liver cells was immunoscreened using common ADAMs antibody to obtain ADAM related genes. We found one positive clone that was confirmed as a new gene by Blast, which is an uncharacterized helical and coil protein and processes protease activity, and named protease-related protein 1 (ARP1). The submitted GenBank accession number is AY078070. Molecular characterizations of ARP1 were analyzed with appropriate bioinformatics software. To analyse its expression and function, ARP1 was subcloned into glutathione S-transferase fusion plasmid pGEX-2T and expressed by E. coli system. The in vitro expression product of ARP1 was recognized by common ADAMs antibody with western blot. Interestingly, ARP1 cleaves gelatine at pH9.5, which suggests it is an alkaline protease. Semi-quantitative RT-PCR result indicates that ARP1 mRNA is strongly transcribed in the liver and the treated Chang-liver cells.
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PMID:Molecular characterization and functional analysis of a protease-related protein in Chang-liver cells. 2051 23


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