ABSTRACT
A mutation, L166P, in the cytosolic protein, PARK7/DJ-1, causes protein misfolding and is linked to Parkinson disease. Here, we identify the fission yeast protein Sdj1 as the orthologue of DJ-1 and calculate by in silico saturation mutagenesis the effects of point mutants on its structural stability. We also map the degradation pathways for Sdj1-L169P, the fission yeast orthologue of the disease-causing DJ-1 L166P protein. Sdj1-L169P forms inclusions, which are enriched for the Hsp104 disaggregase. Hsp104 and Hsp70-type chaperones are required for efficient degradation of Sdj1-L169P. This also depends on the ribosome-associated E3 ligase Ltn1 and its co-factor Rqc1. Although Hsp104 is absolutely required for proteasomal degradation of Sdj1-L169P aggregates, the degradation of already aggregated Sdj1-L169P occurs independently of Ltn1 and Rqc1. Thus, our data point to soluble Sdj1-L169P being targeted early by Ltn1 and Rqc1. The fraction of Sdj1-L169P that escapes this first inspection then forms aggregates that are subsequently cleared via an Hsp104- and proteasome-dependent pathway.
Subject(s)
Adenosine Triphosphatases/metabolism , Coenzymes/metabolism , HSP70 Heat-Shock Proteins/metabolism , Heat-Shock Proteins/metabolism , Intracellular Signaling Peptides and Proteins/chemistry , Oncogene Proteins/chemistry , Schizosaccharomyces pombe Proteins/chemistry , Schizosaccharomyces/metabolism , Ubiquitin-Protein Ligases/metabolism , Adenosine Triphosphatases/genetics , Amino Acid Sequence , Coenzymes/chemistry , HSP70 Heat-Shock Proteins/genetics , Heat-Shock Proteins/genetics , Humans , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Models, Molecular , Molecular Sequence Data , Mutation , Oncogene Proteins/genetics , Oncogene Proteins/metabolism , Proteasome Endopeptidase Complex/metabolism , Protein Aggregates , Protein Deglycase DJ-1 , Protein Folding , Protein Structure, Secondary , Protein Structure, Tertiary , Proteolysis , Schizosaccharomyces/genetics , Schizosaccharomyces pombe Proteins/genetics , Schizosaccharomyces pombe Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Ubiquitin-Protein Ligases/geneticsABSTRACT
Here we report the result of a genetic screen for mutants resistant to the microtubule poison methyl benzimidazol-2-yl carbamate (MBC) that were also temperature sensitive for growth. In total the isolated mutants were distributed in ten complementation groups. Cloning experiments revealed that most of the mutants were in essential genes encoding various 26S proteasome subunits. We found that the proteasome mutants are multi-drug resistant due to stabilization of the stress-activated transcription factor Pap1. We show that the ubiquitylation and ultimately the degradation of Pap1 depend on the Rhp6/Ubc2 E2 ubiquitin conjugating enzyme and the Ubr1 E3 ubiquitin-protein ligase. Accordingly, mutants lacking Rhp6 or Ubr1 display drug-resistant phenotypes.
Subject(s)
Proteasome Endopeptidase Complex/genetics , Schizosaccharomyces pombe Proteins/genetics , Schizosaccharomyces/drug effects , Schizosaccharomyces/genetics , Brefeldin A/pharmacology , Caffeine/pharmacology , Drug Resistance, Multiple , Pancreatitis-Associated Proteins , Staurosporine/pharmacology , UbiquitinationABSTRACT
OBJECTIVES: To study the frequency of a factor of immunodepression in patients with tuberculosis, the differences in presentation, and the diagnosis and therapeutic management according to the immune status. METHODS: Retrospective study of the files of patients hospitalised in the University Hospital Centre of Rennes in 1998 for a Mycobacterium tuberculosis infection. Comparison of two populations, immunodepressed versus non immunodepressed. RESULTS: 75 patients aged 20 to 91 were included, 41 patients were considered immunodepressed and 34 non immunodepressed. The causes of immunodepression were: HIV infection (n = 2), diabetes (n = 4), chronic alcoholism (n = 12), chronic respiratory diseases treated with corticosteroids (n = 6), neoplasia (n = 9), and inflammatory diseases (n = 7). Comparison between the 2 populations revealed more a frequent history of tuberculosis in the immunodepressed (p = 0.04), shorter delay before diagnosis (p = 0.04), greater frequency of disseminated forms (p = 0.02) and enhanced mortality (p = 0.01). There was no difference in the 2 groups with regard to the clinical signs having evoked tuberculosis, the diagnostic method, the bacteriological results or the modalities of treatment. CONCLUSION: The frequent reactivation of tuberculosis in immunodepressed patients and the severity of the infection in these patients should evoke tuberculosis and the rapid initiation of an efficient treatment in such patients. In the case of alteration in immune defences, prophylactic treatment should help to reduce the number of such reactivations.
