Inactivation of the 20S proteasome in <i>Mycobacterium smegmatis</i>

Knipfer, Nancianne; Shrader, Thomas E.

doi:10.1046/j.1365-2958.1997.4721837.x

Cited by 87 publications

(79 citation statements)

References 34 publications

(76 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Simple versions of the proteasome are present in archaea and certain bacteria, while ubiquitin and the ubiquitin conjugating system are not, indicating that the proteasome has the ability to proteolyse at least some nonubiquitinated proteins (298,503). In these organisms, the proteasome is involved in the heat shock response by degrading damaged or misfolded proteins (240,298,379). In vitro, purified core particles from both prokaryotes and eukaryotes can hydrolyze a number of nonubiquitinated unfolded proteins in vitro (87,230,231).…”

Section: Degradation Of Nonubiquitinated Proteinsmentioning

confidence: 99%

The Ubiquitin-Proteasome Proteolytic Pathway: Destruction for the Sake of Construction

Glickman

Ciechanover

2002

Physiological Reviews

3,717

3,031

View full text Add to dashboard Cite

Between the 1960s and 1980s, most life scientists focused their attention on studies of nucleic acids and the translation of the coded information. Protein degradation was a neglected area, considered to be a nonspecific, dead-end process. Although it was known that proteins do turn over, the large extent and high specificity of the process, whereby distinct proteins have half-lives that range from a few minutes to several days, was not appreciated. The discovery of the lysosome by Christian de Duve did not significantly change this view, because it became clear that this organelle is involved mostly in the degradation of extracellular proteins, and their proteases cannot be substrate specific. The discovery of the complex cascade of the ubiquitin pathway revolutionized the field. It is clear now that degradation of cellular proteins is a highly complex, temporally controlled, and tightly regulated process that plays major roles in a variety of basic pathways during cell life and death as well as in health and disease. With the multitude of substrates targeted and the myriad processes involved, it is not surprising that aberrations in the pathway are implicated in the pathogenesis of many diseases, certain malignancies, and neurodegeneration among them. Degradation of a protein via the ubiquitin/proteasome pathway involves two successive steps: 1) conjugation of multiple ubiquitin moieties to the substrate and 2) degradation of the tagged protein by the downstream 26S proteasome complex. Despite intensive research, the unknown still exceeds what we currently know on intracellular protein degradation, and major key questions have remained unsolved. Among these are the modes of specific and timed recognition for the degradation of the many substrates and the mechanisms that underlie aberrations in the system that lead to pathogenesis of diseases.

show abstract

Section: Degradation Of Nonubiquitinated Proteinsmentioning

confidence: 99%

The Ubiquitin-Proteasome Proteolytic Pathway: Destruction for the Sake of Construction

Glickman

Ciechanover

2002

Physiological Reviews

3,717

3,031

View full text Add to dashboard Cite

show abstract

“…Therefore, we wished to identify an LMW Suc-LLVY-AMC-cleaving peptidase from another actinomycetale, M. smegmatis, which also encodes 20 S proteasomes (17). Interestingly, a Suc-LLVY-AMC hydrolyzing activity was observed in M. smegmatis lacking 20 S proteasomes (17), although the identity of this enzyme(s) was not established. Cellular extracts from M. smegmatis after SDG fractionation displayed low and high molecular weight peaks of activity (Fig.…”

Section: An Lmw Suc-llvy-amc-cleaving Enzyme Is a Pepn Homologue In Mmentioning

confidence: 99%

“…Prokaryotes, on the other hand, possess redundant proteolytic systems. E. coli strains lacking lon and clp (2) and Mycobacterium smegmatis lacking 20 S proteasomes (17) are viable, whereas Thermoplasma 20 S proteasomes are important only under conditions of heat shock (18). Both prokaryotes and eukaryotes possess oligopeptidases and exopeptidases that act during the later (steps iii and iv) stages of protein degradation.…”

mentioning

confidence: 99%

PepN, the Major Suc-LLVY-AMC-hydrolyzing Enzyme inEscherichia coli, Displays Functional Similarity with Downstream Processing Enzymes in Archaea and Eukarya

Chandu

Kumar

Nandi

2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

Succinyl-Leu-Leu-Val-Tyr-7-amido-4-methylcoumarin (Suc-LLVY-AMC), a fluorogenic endopeptidase substrate, is used to detect 20 S proteasomal activity from Archaea to mammals. An o-phenanthroline-sensitive Suc-LLVY-AMC hydrolyzing activity was detected in Escherichia coli although it lacks 20 S proteasomes. We identified PepN, previously characterized as the sole alanine aminopeptidase in E. coli, to be responsible for the hydrolysis of Suc-LLVY-AMC. PepN is an aminoendopeptidase. First, extracts from an ethyl methanesulfonate-derived PepN mutant, 9218, did not cleave Suc-LLVY-AMC and L-Ala-para-nitroanilide (pNA). Second, biochemically purified PepN cleaves a wide variety of both aminopeptidase and endopeptidase substrates, and L-Ala-pNA is cleaved more efficiently than other substrates. Studies with bestatin, an aminopeptidasespecific inhibitor, suggest differences in the mechanisms of cleavage of aminopeptidase and endopeptidase substrates. Third, PepN hydrolyzes whole proteins, casein and albumin. Finally, an E. coli strain with a targeted deletion in PepN also lacks the ability to cleave Suc-LLVY-AMC and L-Ala-pNA, and expression of wild type PepN in this mutant rescues both activities. In addition, we identified a low molecular weight Suc-LLVY-AMC-cleaving peptidase in Mycobacterium smegmatis, a eubacteria harboring 20 S proteasomes, to be an aminopeptidase homologous to E. coli PepN, by mass spectrometry analysis. "Sequence-based homologues" of PepN include well characterized aminopeptidases, e.g. Tricorn interacting factors F2 and F3 in Archaea and puromycin-sensitive aminopeptidase in mammals. However, our results suggest that eubacterial PepN and its homologues displaying aminoendopeptidase activities may be "functionally similar" to enzymes important in downstream processing of proteins in the cytosol: Tricorn-F1-F2-F3 complex in Archaea and TPPII/Multicorn in eukaryotes.Dynamic changes in the proteome of a cell depend on rates of protein synthesis and their degradation. The past few decades have witnessed enormous strides in identifying the molecules and understanding the mechanisms involved in intracellular protein degradation. There is increasing evidence of the involvement of protein degradation in diverse biological activities, e.g. cell cycle progression, transcriptional activation, antigen processing, disease progression, etc. (1-5).Broadly, cytosolic protein degradation is categorized into four steps. (i) Proteins targeted for degradation are initially unfolded into polypeptides by ATP-dependent proteases belonging to the Lon/Clp family in bacteria or 26 S proteasomes in higher organisms (1-5). (ii) These enzymes also make the initial endoproteolytic "cuts" in the polypeptide. Interestingly, in both Escherichia coli (6) and higher organisms (7) the average length of peptides released by these enzymes range from 3 to 25 amino acids. (iii) These longer peptides are trimmed into smaller peptides (less than 10 amino acids) by the action of endopeptidases (8 -11), tripeptidyl-and dipeptidylpeptidases...

show abstract

“…Bacterial proteasomes, which are unique to actinomycetes 14,15 , are not essential for in vitro growth of Streptomyces coelicolor, S. lividans, or M. smegmatis [16][17][18] . In contrast, prcA and prcB were predicted to be essential for optimal in vitro growth of Mtb 6 .…”

mentioning

confidence: 99%

In vivo gene silencing identifies the Mycobacterium tuberculosis proteasome as essential for the bacteria to persist in mice

Gandotra

Schnappinger

Monteleone

et al. 2007

Nat Med

231

270

View full text Add to dashboard Cite

show abstract

Inactivation of the 20S proteasome in Mycobacterium smegmatis

Cited by 87 publications

References 34 publications

The Ubiquitin-Proteasome Proteolytic Pathway: Destruction for the Sake of Construction

The Ubiquitin-Proteasome Proteolytic Pathway: Destruction for the Sake of Construction

PepN, the Major Suc-LLVY-AMC-hydrolyzing Enzyme inEscherichia coli, Displays Functional Similarity with Downstream Processing Enzymes in Archaea and Eukarya

In vivo gene silencing identifies the Mycobacterium tuberculosis proteasome as essential for the bacteria to persist in mice

Contact Info

Product

Resources

About