Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The S13 subunit (also called Pad1, Rpn11, and MPR1) is a component of the 19S complex, a regulatory complex essential for the ubiquitin-dependent proteolytic activity of the 26S proteasome. To address the functional role of S13, we combined double-stranded RNA interference (RNAi) against the Drosophila proteasome subunit DmS13 with expression of wild-type and mutant forms of the homologous human gene, HS13. These studies show that DmS13 is essential for 26S function. Loss of the S13 subunit in metazoan cells leads to increased levels of ubiquitin conjugates, cell cycle defects, DNA overreplication, and apoptosis. In vivo assays using short-lived proteasome substrates confirmed that the 26S ubiquitin-dependent degradation pathway is compromised in S13-depleted cells. In complementation experiments using Drosophila cell lines expressing HS13, wild-type HS13 was found to fully rescue the knockdown phenotype after DmS13 RNAi treatment, while an HS13 containing mutations (H113A-H115A) in the proposed isopeptidase active site was unable to rescue. A mutation within the conserved MPN/JAMM domain (C120A) abolished the ability of HS13 to rescue the Drosophila cells from apoptosis or DNA overreplication. However, the C120A mutant was found to partially restore normal levels of ubiquitin conjugates. The S13 subunit may possess multiple functions, including a deubiquitinylating activity and distinct activities essential for cell cycle progression that require the conserved C120 residue.
Mol Cell Biol 2003 Aug
PMID:Use of RNA interference and complementation to study the function of the Drosophila and human 26S proteasome subunit S13. 1286 Oct 18

Mammalian neuronal cells abundantly express a deubiquitylating enzyme, ubiquitin carboxy-terminal hydrolase 1 (UCH L1). Mutations in UCH L1 are linked to Parkinson's disease as well as gracile axonal dystrophy (gad) in mice. In contrast to the UCH L3 isozyme that is universally expressed in all tissues, UCH L1 is expressed exclusively in neurons and testis/ovary. We found that UCH L1 associates and colocalizes with monoubiquitin and elongates ubiquitin half-life. The gad mouse, in which the function of UCH L1 is lost, exhibited a reduced level of monoubiquitin in neurons. In contrast, overexpression of UCH L1 caused an increase in the level of ubiquitin in both cultured cells and mice. These data suggest that UCH L1, with avidity and affinity for ubiquitin, insures ubiquitin stability within neurons. This study is the first to show the function of UCH L1 in vivo.
Hum Mol Genet 2003 Aug 15
PMID:Ubiquitin carboxy-terminal hydrolase L1 binds to and stabilizes monoubiquitin in neuron. 1291 66

The lysozyme of the marine bilave Tapes japonica (13.8 kDa) is a novel protein. The protein has 46% homology with the destabilase from medicinal leech that has isopeptidase activity. Based on these data, we confirmed hydrolysis activity of T. japonica lysozyme against three substrates: L-gamma-Glu-pNA, D-gamma-Glu-pNA, and epsilon-(gamma-Glu)-L-Lys. The optimal pH of chitinase and isopeptidase activity was 5.0 and 7.0, respectively. The isopeptidase activity was inhibited with serine protease inhibitor, but the lytic and chitinase activities were not. Moreover, only isopeptidase activity is decreased by lyophilization, but lytic and chitinase activities were not. We conclude that T. japonica lysozyme expresses isopeptidase and chitinase activity at different active sites.
Cell Mol Life Sci 2003 Sep
PMID:A small chimerically bifunctional monomeric protein: Tapes japonica lysozyme. 1452 54

Modification of proteins by ubiquitin (Ub)-like proteins (UBLs) plays an important role in many cellular processes, including cell cycle progression, nuclear transport, and autophagy. Protein modification occurs via UBL-conjugating and -deconjugating enzymes, which presumably exert a regulatory function by determining the conjugation status of the substrate proteins. To target and identify UBL-modifying enzymes, we produced Nedd8, ISG15, and SUMO-1 in Escherichia coli and equipped them with a C-terminal electrophilic trap (vinyl sulfone [VS]) via an intein-based method. These C-terminally modified UBL probes reacted with purified UBL-activating (E1), -conjugating (E2), and -deconjugating enzymes in a covalent fashion. Modified UBLs were radioiodinated and incubated with cell lysates prepared from mouse cell lines and tissues to allow visualization of polypeptides reactive with individual UBL probes. The cell type- and tissue-specific labeling patterns observed for the UBL probes reflect distinct expression profiles of active enzymes, indicating tissue-specific functions of UBLs. We identify Ub C-terminal hydrolase L1 (UCH-L1) and DEN1/NEDP1/SENP8, in addition to UCH-L3, as proteases with specificity for Nedd8. The Ub-specific protease isopeptidase T/USP5 is shown to react with ISG15-VS. Furthermore, we demonstrate that the desumoylation enzyme SuPr-1 can be modified by SUMO-1-VS, a modification that is dependent on the SuPr-1 active-site cysteine. The UBL probes described here will be valuable tools for the further characterization of the enzymatic pathways that govern modification by UBLs.
Mol Cell Biol 2004 Jan
PMID:Specific and covalent targeting of conjugating and deconjugating enzymes of ubiquitin-like proteins. 1467 45

Homologs of the Yersinia virulence factor YopJ are found in both animal and plant bacterial pathogens, as well as in plant symbionts. The conservation of this effector family indicates that several pathogens may use YopJ-like proteins to regulate bacteria-host interactions during infection. YopJ and YopJ-like proteins share structural homology with cysteine proteases and are hypothesized to functionally mimic small ubiquitin-like modifier (SUMO) proteases in eukaryotic cells. Strains of the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria are known to possess four YopJ-like proteins, AvrXv4, AvrBsT, AvrRxv, and XopJ. In this work, we have characterized AvrXv4 to determine if AvrXv4 functions like a SUMO protease in planta during Xanthomonas-plant interactions. We provide evidence that X. campestris pv. vesicatoria secretes and translocates the AvrXv4 protein into plant cells during infection in a type III-dependent manner. Once inside the plant cell, AvrXv4 is localized to the plant cytoplasm. By performing AvrXv4 deletion and mutational analysis, we have identified amino acids required for type III delivery and for host recognition. We show that AvrXv4 recognition by resistant plants requires a functional protease catalytic core, the domain that is conserved in all of the putative YopJ-like cysteine proteases. We also show that AvrXv4 expression in planta leads to a reduction in SUMO-modified proteins, demonstrating that AvrXv4 possesses SUMO isopeptidase activity. Overall, our studies reveal that the YopJ-like effector AvrXv4 encodes a type III SUMO protease effector that is active in the cytoplasmic compartment of plant cells.
Mol Plant Microbe Interact 2004 Jun
PMID:Characterization of the Xanthomonas AvrXv4 effector, a SUMO protease translocated into plant cells. 1519 46

Parkinson's disease (PD) is a multifactorial disease that appears to arise from the effects of both genetic and environmental influences. Pesticides and heavy metals are the principle environmental factors that appear to impact on PD. The known genetic factors include multiple genes that have been identified in related parkinsonian syndromes, as well as alpha-synuclein. Genes associated with either PD or Parkinson-related disorders include parkin, DJ-1, ubiquitin C-terminal hydrolase isozyme L1 (UCH-L1), nuclear receptor-related factor 1, and alpha-synuclein. Alpha-synuclein is particularly notable because it aggregates readily and is the main component of Lewy bodies (LBs). Aggregated alpha-synuclein binds the proteasome and potently inhibits proteasomal activity. Because ubiquitin accumulates in LBs, and parkin and UCH-L1 also interact with the ubiquitin proteasomal system, proteasomal dysfunction is thought to contribute to the pathophysiology of PD. Increasing numbers of experiments suggest that neurotoxins might interact with alpha-synuclein or other Parkinson-related proteins to contribute to the pathophysiology of PD. Transgenic animal models overexpressing alpha-synuclein develop age-dependent motor dysfunction and inclusions in the brain stem that contain alpha-synuclein. These models are very helpful in elucidating the pathophysiology of PD but do not completely recapitulate the disease process. The relationship between these transgenic models and PD is a subject of intense investigation.
J Mol Neurosci 2004
PMID:Pathological proteins in Parkinson's disease: focus on the proteasome. 1565 64

Structural analysis of nuclear receptor subfamily V orphan nuclear receptors suggests that ligand-independent mechanisms must regulate this subclass of receptors. Here, we report that steroidogenic factor 1 (SF-1) and liver receptor homolog 1 are repressed via posttranslational SUMO modification at conserved lysines within the hinge domain. Indeed, mutating these lysines or adding the SUMO isopeptidase SENP1 dramatically increased both native and Gal4-chimera receptor activities. The mechanism by which SUMO conjugation attenuates SF-1 activity was found to be largely histone deacetylase independent and was unaffected by the AF2 corepressor Dax1. Instead, our data suggest that SUMO-mediated repression involves direct interaction of the DEAD-box protein DP103 with sumoylated SF-1. Of potential E3-SUMO ligase candidates, PIASy and PIASxalpha strongly promoted SF-1 sumoylation, and addition of DP103 enhanced both PIAS-dependent receptor sumoylation and SF-1 relocalization to discrete nuclear bodies. Taken together, we propose that DEAD-box RNA helicases are directly coupled to transcriptional repression by protein sumoylation.
Mol Cell Biol 2005 Mar
PMID:The DEAD-box protein DP103 (Ddx20 or Gemin-3) represses orphan nuclear receptor activity via SUMO modification. 1571 42

Maintaining adequate proteasomal proteolytic activity is essential for eukaryotic cells. For metazoan cells, little is known about the composition of genes that are regulated in the proteasome network or the mechanisms that modulate the levels of proteasome genes. Previously, two distinct treatments have been observed to induce 26S proteasome levels in Drosophila melanogaster cell lines, RNA interference (RNAi)-mediated inhibition of the 26S proteasome subunit Rpn10/S5a and suppression of proteasome activity through treatment with active-site inhibitors. We have carried out genome array profiles from cells with decreased Rpn10/S5a levels using RNAi or from cells treated with proteasome inhibitor MG132 and have thereby identified candidate genes that are regulated as part of a metazoan proteasome network. The profiles reveal that the majority of genes that were identified to be under the control of the regulatory network consisted of 26S proteasome subunits. The 26S proteasome genes, including three new subunits, Ubp6p, Uch-L3, and Sem1p, were found to be up-regulated. A number of genes known to have proteasome-related functions, including Rad23, isopeptidase T, sequestosome, and the genes for the segregase complex TER94/VCP-Ufd1-Npl4 were also found to be up-regulated. RNAi-mediated inhibition against the segregase complex genes demonstrated pronounced stabilization of proteasome substrates throughout the Drosophila cell. Finally, transcriptional reporter assays and deletion mapping studies in Drosophila demonstrate that proteasome mRNA induction is dependent upon the 5' untranslated regions (UTRs). Transfer of the 5' UTR from the proteasome subunit Rpn1/S2 to a noninducible promoter was sufficient to confer transcriptional upregulation of the reporter mRNA after proteasome inhibition.
Mol Cell Biol 2005 Jun
PMID:Identification and characterization of a Drosophila proteasome regulatory network. 1589 68

Despite the identification of numerous deubiquitinating enzymes (DUBs) in recent years, the large majority of this class of enzymes has not been well characterized. This chapter describes biochemical methods that can be used to characterize the function and substrate specificity of DUBs. Methods described will include: fluorescence assay using ubiquitin-amidomethylcoumarin (AMC); a high-performance liquid chromatography assay using ubiquitin ethyl ester or ubiquitin fusion peptides as model substrates to monitor DUB activity; and the purification of a recombinant human DUB, isopeptidase T, in E. coli using low-temperature expression as well as ion-exchange and affinity chromatography.
Methods Mol Biol 2005
PMID:Deubiquitinating enzyme purification, assay inhibitors, and characterization. 1591 34

Although neurochemical changes have been reported in the brain in animal models of binge eating, biochemical changes of specific proteins in the brain are unknown. Our aim was to elucidate brain proteins altered in rats during enhanced rebound hyperphargia. Rats were deprived of food for 22 h/day for 6 days, then allowed free access to food for 24 h in normal cages (rebound hyperphargia) or in space-restricted cages (enhanced rebound hyperphargia). Proteins extracted from the rat brain were separated by two-dimensional gel electrophoresis, and compared with those from control rats freely fed for 7 days in normal cages. Proteins expressed differently from controls were identified by N-terminal amino acid sequencing and mass fingerprinting using a MALDI-TOF mass spectrometer. Among proteins in the corpus striatum, frontal lobe, hippocampus and thalamus/hypothalamus, ubiquitin C-terminal hydrolase L1 and peroxiredoxin 2 decreased in the hippocampus and phosphatidylethanolamine-binding protein increased in the thalamus/hypothalamus of rats with the enhanced rebound hyperphargia induced by space-restriction. In this study, we first demonstrated that three brain proteins changed in rats during enhanced rebound hyperphagia. These proteins might have pathophysiologic relevance to binge eating.
Mol Cell Biochem 2005 Aug
PMID:A comparative proteomic analysis of the rat brain during rebound hyperphagia induced by space-restriction. 1613 81


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