Fungal ribotoxins: a family of naturally engineered targeted toxins?

1995 ◽  
Vol 73 (11-12) ◽  
pp. 1151-1159 ◽  
Author(s):  
Richard Kao ◽  
Julian Davies
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Subunits ◽  
Site Specific ◽  
Phosphodiester Bond ◽  
Ribosome Inactivating Proteins ◽  
Diagnostic Agents ◽  
Molecular Studies ◽  
Related Proteins ◽  
Targeted Toxins

α-Sarcin, mitogillin, and restrictocin are small (~17 kDa) basic ribosome-inactivating proteins (RIPs) produced by the Aspergilli that catalytically inactivate the large ribosomal subunits of all organisms tested to date. These three fungal ribotoxins act as specific ribonucleases by hydrolyzing one single phosphodiester bond in the universally conserved α-sarcin domain of 23–28S rRNAs and are among the most potent inhibitors of protein synthesis known. Previous molecular studies of ribotoxins indicated that they belong to the superfamily of ribonucleases and analysis of the mitogillin gene employing PCR-mediated site-specific mutagenesis suggests that certain domains in ribotoxins, which share homologies with motifs in ribosome-related proteins, may be responsible for the targeting of ribotoxins to the ribosome. The applications of the ribotoxins as tools in research and their uses as therapeutic and diagnostic agents are also reviewed in this paper.Key words: ribotoxins, mitogillin, α-sarcin loop, protein synthesis, aspergillosis, immunotoxins.

scholarly journals LOCALIZED MUTAGENESIS FOR THE ISOLATION OF TEMPERATURE-SENSITIVE MUTANTS OF ESCHERICHIA COLI AFFECTED IN PROTEIN SYNTHESIS

Genetics ◽  
1979 ◽  
Vol 91 (2) ◽  
pp. 215-227
Author(s):  
W Scott Champney
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Temperature Sensitive ◽  
Chromosomal Locus ◽  
Ribosomal Subunits ◽  
Prolonged Incubation ◽  
Temperature Sensitive Mutants ◽  
Inhibition Of Growth ◽  
Localized Mutagenesis

ABSTRACT Two variations of the method of localized mutagenesis were used to introduce mutations into the 72 min region of the Escherichia coli chromosome. Twenty temperature-sensitive mutants, with linkage to markers in this region, have been examined. Each strain showed an inhibition of growth in liquid medium at 44°, and 19 of the mutants lost viability upon prolonged incubation at this temperature. A reduction in the rate of in vivo RNA and protein synthesis was observed for each mutant at 44°, relative to a control strain. Eleven of the mutants were altered in growth sensitivity or resistance to one or more of three ribosomal antibiotics. The incomplete assembly of ribosomal subunits was detected in nine strains grown at 44°. The characteristics of these mutants suggest that many of them are altered in genes for translational or transcriptional components, consistent with the clustering of these genes at this chromosomal locus.

scholarly journals The Oxazolidinone Linezolid Inhibits Initiation of Protein Synthesis in Bacteria

1998 ◽  
Vol 42 (12) ◽  
pp. 3251-3255 ◽  
Author(s):  
Steve M. Swaney ◽  
Hiroyuki Aoki ◽  
M. Clelia Ganoza ◽  
Dean L. Shinabarger
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Antimicrobial Agents ◽  
Ribosomal Subunit ◽  
Multidrug Resistant ◽  
Binary Complex ◽  
Initiation Complex ◽  
Ribosomal Subunits ◽  
Bacterial Translation

ABSTRACT The oxazolidinones represent a new class of antimicrobial agents which are active against multidrug-resistant staphylococci, streptococci, and enterococci. Previous studies have demonstrated that oxazolidinones inhibit bacterial translation in vitro at a step preceding elongation but after the charging ofN-formylmethionine to the initiator tRNA molecule. The event that occurs between these two steps is termed initiation. Initiation of protein synthesis requires the simultaneous presence of N-formylmethionine-tRNA, the 30S ribosomal subunit, mRNA, GTP, and the initiation factors IF1, IF2, and IF3. An initiation complex assay measuring the binding of [3H]N-formylmethionyl-tRNA to ribosomes in response to mRNA binding was used in order to investigate the mechanism of oxazolidinone action. Linezolid inhibited initiation complex formation with either the 30S or the 70S ribosomal subunits fromEscherichia coli. In addition, complex formation withStaphylococcus aureus 70S tight-couple ribosomes was inhibited by linezolid. Linezolid did not inhibit the independent binding of either mRNA or N-formylmethionyl-tRNA toE. coli 30S ribosomal subunits, nor did it prevent the formation of the IF2–N-formylmethionyl-tRNA binary complex. The results demonstrate that oxazolidinones inhibit the formation of the initiation complex in bacterial translation systems by preventing formation of theN-formylmethionyl-tRNA–ribosome–mRNA ternary complex.

Regulation of hepatic protein synthesis in chronic inflammation and sepsis

1992 ◽  
Vol 262 (2) ◽  
pp. C445-C452 ◽  
Author(s):  
T. C. Vary ◽  
S. R. Kimball
Keyword(s):  
Protein Synthesis ◽  
Sterile Inflammation ◽  
Chain Elongation ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Translational Efficiency ◽  
Liver Protein ◽  
Ribosomal Subunits ◽  
Hepatic Protein Synthesis

The regulation of protein synthesis was determined in livers from control, sterile inflammatory, and septic animals. Total liver protein was increased in both sterile inflammation and sepsis. The rate of protein synthesis in vivo was measured by the incorporation of [3H]phenylalanine into liver proteins in a chronic (5 day) intra-abdominal abscess model. Both sterile inflammation and sepsis increased total hepatic protein synthesis approximately twofold. Perfused liver studies demonstrated that the increased protein synthesis rate in vivo resulted from a stimulation in the synthesis of both secreted and nonsecreted proteins. The total hepatic RNA content was increased 40% only in sterile inflammation, whereas the translational efficiency was increased twofold only in sepsis. The increase in translational efficiency was accompanied by decreases in the amount of free 40S and 60S ribosomal subunits in sepsis. Rates of peptide-chain elongation in vivo were increased 40% in both sterile inflammation and sepsis. These results demonstrate that sepsis induces changes in the regulation of hepatic protein synthesis that are independent of the general inflammatory response. In sterile inflammation, the increase in protein synthesis occurs by a combination of increased capacity and translational efficiency, while in sepsis, the mechanism responsible for accelerated protein synthesis is an increased translational efficiency.

scholarly journals An ankyrin-related gene (unc-44) is necessary for proper axonal guidance in Caenorhabditis elegans.

1995 ◽  
Vol 129 (4) ◽  
pp. 1081-1092 ◽  
Author(s):  
A J Otsuka ◽  
R Franco ◽  
B Yang ◽  
K H Shim ◽  
L Z Tang ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Nucleotide Sequence ◽  
Axon Guidance ◽  
Axonal Guidance ◽  
Related Gene ◽  
Sequence Analyses ◽  
Molecular Analyses ◽  
Molecular Studies ◽  
Alternatively Spliced ◽  
Related Proteins

Caenorhabditis elegans unc-44 mutations result in aberrant axon guidance and fasciculation with inappropriate partners. The unc-44 gene was cloned by transposon tagging, and verified by genetic and molecular analyses of six transposon-induced alleles and their revertants. Nucleotide sequence analyses demonstrated that unc-44 encodes a series of putative ankyrin-related proteins, including AO49 ankyrin (1815 aa, 198.8 kD), AO66 ankyrin (1867 aa, 204 kD), and AO13 ankyrin (< or = 4700 aa, < or = 517 kD). In addition to the major set of approximately 6 kb alternatively spliced transcripts, minor transcripts were observed at approximately 3, 5, 7, and 14 kb. Evidence is provided that mutations in the approximately 14-kb AO13 ankyrin transcript are responsible for the neuronal defects. These molecular studies provide the first evidence that ankyrin-related molecules are required for axonal guidance.

Energy dependence of RNA degradation in rabbit reticulocytes

1984 ◽  
Vol 247 (5) ◽  
pp. C390-C395 ◽  
Author(s):  
E. A. Park ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Rna Degradation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Energy Dependent ◽  
Rabbit Reticulocytes

RNA degradation in rabbit reticulocytes was partially energy dependent. Reticulocytes were incubated for 10 h in Krebs-Henseleit bicarbonate buffer that was gassed with 95% O2-5% CO2 and contained glucose (30 mM) or 2-deoxyglucose (20 mM) and 2,4-dinitrophenol (0.2 mM). The rate of RNA degradation was reduced 41% in the presence of the metabolic inhibitors. When the buffer was gassed with 95% N2-5% CO2 and no substrate was added, the disappearance of RNA was decreased 55%. The cellular ATP content was depleted either by addition of the metabolic inhibitors or by incubation under anoxic conditions. ATP depletion did not modify the ratio of ribosomal subunits + monomers to polysomes. Puromycin and cycloheximide, which increased or decreased, respectively, the proportion of ribosomal RNA in subunits + monomers, blocked protein synthesis but did not alter the rate of RNA degradation. These experiments indicated that energy depletion inhibited RNA degradation by a mechanism that did not depend on the inhibition of protein synthesis. No evidence was obtained to indicate that the ratio of subunits + monomers to polysomes affected RNA degradation.

scholarly journals Multidimensional Proteomics Identifies Declines in Protein Homeostasis and Mitochondria as Early Signals for Normal Aging and Age-associated Disease in Drosophila

2019 ◽  
Vol 18 (10) ◽  
pp. 2078-2088 ◽  
Author(s):  
Lu Yang ◽  
Ye Cao ◽  
Jing Zhao ◽  
Yanshan Fang ◽  
Nan Liu ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Dynamics ◽  
Isotope Labeling ◽  
Specific Protein ◽  
Normal Aging ◽  
Protein Homeostasis ◽  
Age Related ◽  
Muscle Tissues ◽  
Proteomic Study ◽  
Related Proteins

Aging is characterized by a gradual deterioration in proteome. However, how protein dynamics that changes with normal aging and in disease is less well understood. Here, we profiled the snapshots of aging proteome in Drosophila, from head and muscle tissues of post-mitotic somatic cells, and the testis of mitotically-active cells. Our data demonstrated that dysregulation of proteome homeostasis, or proteostasis, might be a common feature associated with age. We further used pulsed metabolic stable isotope labeling analysis to characterize protein synthesis. Interestingly, this study determined an age-modulated decline in protein synthesis with age, particularly in the pathways related to mitochondria, neurotransmission, and proteostasis. Importantly, this decline became dramatically accelerated in Pink1 mutants, a Drosophila model of human age-related Parkinson's disease. Taken together, our multidimensional proteomic study revealed tissue-specific protein dynamics with age, highlighting mitochondrial and proteostasis-related proteins. We suggest that declines in proteostasis and mitochondria early in life are critical signals prior to the onset of aging and aging-associated diseases.

Function of Three Protein Factors and Ribosomal Subunits in the Initiation of Protein Synthesis in E. coli

Nature ◽  
1968 ◽  
Vol 219 (5158) ◽  
pp. 1016-1021 ◽  
Author(s):  
M. REVEL ◽  
J. C. LELONG ◽  
G. BRAWERMAN ◽  
F. GROS
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Subunits ◽  
E Coli

scholarly journals THE INTRACELLULAR SITE OF SYNTHESIS OF MITOCHONDRIAL RIBOSOMAL PROTEINS IN NEUROSPORA CRASSA

1972 ◽  
Vol 54 (1) ◽  
pp. 56-74 ◽  
Author(s):  
Paul M. Lizardi ◽  
David J. L. Luck
Keyword(s):  
Protein Synthesis ◽  
Isoelectric Focusing ◽  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Mitochondrial Protein ◽  
Selective Inhibitor ◽  
Mitochondrial Protein Synthesis ◽  
Ribosomal Subunits

The intracellular site of synthesis of mitochondrial ribosomal proteins (MRP) in Neurospora crassa has been investigated using three complementary approaches. (a) Mitochondrial protein synthesis in vitro: Tritium-labeled proteins made by isolated mitochondria were compared to 14C-labeled marker MRP by cofractionation in a two-step procedure involving isoelectric focusing and polyacrylamide gel electrophoresis. Examination of the electrophoretic profiles showed that essentially none of the peaks of in vitro product corresponded exactly to any of the MRP marker peaks. (b) Sensitivity of in vivo MRP synthesis to chloramphenicol: Cells were labeled with leucine-3H in the presence of chloramphenicol, mitochondrial ribosomal subunits were subsequently isolated, and their proteins fractionated by isoelectric focusing followed by gel electrophoresis. The labeling of every single MRP was found to be insensitive to chloramphenicol, a selective inhibitor of mitochondrial protein synthesis. (c) Sensitivity of in vivo MRP synthesis to anisomycin: We have found this antibiotic to be a good selective inhibitor of cytoplasmic protein synthesis in Neurospora. In the presence of anisomycin the labeling of virtually all MRP is inhibited to the same extent as the labeling of cytoplasmic ribosomal proteins. On the basis of these three types of studies we conclude that most if not all 53 structural proteins of mitochondrial ribosomal subunits in Neurospora are synthesized by cytoplasmic ribosomes.

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