1
|
Shirokikh NE. Translation complex stabilization on messenger RNA and footprint profiling to study the RNA responses and dynamics of protein biosynthesis in the cells. Crit Rev Biochem Mol Biol 2021; 57:261-304. [PMID: 34852690 DOI: 10.1080/10409238.2021.2006599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
During protein biosynthesis, ribosomes bind to messenger (m)RNA, locate its protein-coding information, and translate the nucleotide triplets sequentially as codons into the corresponding sequence of amino acids, forming proteins. Non-coding mRNA features, such as 5' and 3' untranslated regions (UTRs), start sites or stop codons of different efficiency, stretches of slower or faster code and nascent polypeptide interactions can alter the translation rates transcript-wise. Most of the homeostatic and signal response pathways of the cells converge on individual mRNA control, as well as alter the global translation output. Among the multitude of approaches to study translational control, one of the most powerful is to infer the locations of translational complexes on mRNA based on the mRNA fragments protected by these complexes from endonucleolytic hydrolysis, or footprints. Translation complex profiling by high-throughput sequencing of the footprints allows to quantify the transcript-wise, as well as global, alterations of translation, and uncover the underlying control mechanisms by attributing footprint locations and sizes to different configurations of the translational complexes. The accuracy of all footprint profiling approaches critically depends on the fidelity of footprint generation and many methods have emerged to preserve certain or multiple configurations of the translational complexes, often in challenging biological material. In this review, a systematic summary of approaches to stabilize translational complexes on mRNA for footprinting is presented and major findings are discussed. Future directions of translation footprint profiling are outlined, focusing on the fidelity and accuracy of inference of the native in vivo translation complex distribution on mRNA.
Collapse
Affiliation(s)
- Nikolay E Shirokikh
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| |
Collapse
|
2
|
Abstract
Biomolecular condensates concentrate molecules to facilitate basic biochemical processes, including transcription and DNA replication. While liquid-like condensates have been ascribed various functions, solid-like condensates are generally thought of as amorphous sites of protein storage. Here, we show that solid-like amyloid bodies coordinate local nuclear protein synthesis (LNPS) during stress. On stimulus, translationally active ribosomes accumulate along fiber-like assemblies that characterize amyloid bodies. Mass spectrometry analysis identified regulatory ribosomal proteins and translation factors that relocalize from the cytoplasm to amyloid bodies to sustain LNPS. These amyloidogenic compartments are enriched in newly transcribed messenger RNA by Heat Shock Factor 1 (HSF1). Depletion of stress-induced ribosomal intergenic spacer noncoding RNA (rIGSRNA) that constructs amyloid bodies prevents recruitment of the nuclear protein synthesis machinery, abolishes LNPS, and impairs the nuclear HSF1 response. We propose that amyloid bodies support local nuclear translation during stress and that solid-like condensates can facilitate complex biochemical reactions as their liquid counterparts can.
Collapse
|
3
|
Picocyanobacterial Contribution to the Total Primary Production in the Northwestern Pacific Ocean. WATER 2021. [DOI: 10.3390/w13111610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Picocyanobacteria (Prochlorococcus and Synechococcus) play an important role in primary production and biogeochemical cycles in the subtropical and tropical Pacific Ocean, but little biological information on them is currently available in the North Pacific Ocean (NPO). The present study aimed to determine the picocyanobacterial contributions to the total primary production in the regions in the NPO using a combination of a dual stable isotope method and metabolic inhibitor. In terms of cell abundance, Prochlorococcus were mostly dominant (95.7 ± 1.4%) in the tropical Pacific region (hereafter, TP), whereas Synechococcus accounted for 50.8%–93.5% in the subtropical and temperate Pacific region (hereafter, SP). Regionally, the averages of primary production and picocyanobacterial contributions were 11.66 mg C m−2·h−1 and 45.2% (±4.8%) in the TP and 22.83 mg C m−2·h−1 and 70.2% in the SP, respectively. In comparison to the carbon, the average total nitrogen uptake rates and picocyanobacterial contributions were 10.11 mg N m−2·h−1 and 90.2% (±5.3%) in the TP and 4.12 mg N m−2·h−1 and 63.5%, respectively. These results indicate that picocyanobacteria is responsible for a large portion of the total primary production in the region, with higher contribution to nitrogen uptake rate than carbon. A long-term monitoring on the picocyanobacterial variability and contributions to primary production should be implemented under the global warming scenario with increasing ecological roles of picocyanobacteria.
Collapse
|
4
|
Abushaheen MA, Muzaheed, Fatani AJ, Alosaimi M, Mansy W, George M, Acharya S, Rathod S, Divakar DD, Jhugroo C, Vellappally S, Khan AA, Shaik J, Jhugroo P. Antimicrobial resistance, mechanisms and its clinical significance. Dis Mon 2020; 66:100971. [PMID: 32201008 DOI: 10.1016/j.disamonth.2020.100971] [Citation(s) in RCA: 157] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Antimicrobial agents play a key role in controlling and curing infectious disease. Soon after the discovery of the first antibiotic, the challenge of antibiotic resistance commenced. Antimicrobial agents use different mechanisms against bacteria to prevent their pathogenesis and they can be classified as bactericidal or bacteriostatic. Antibiotics are one of the antimicrobial agents which has several classes, each with different targets. Consequently, bacteria are endlessly using methods to overcome the effectivity of the antibiotics by using distinct types of mechanisms. Comprehending the mechanisms of resistance is vital for better understanding and to continue use of current antibiotics. Which also helps to formulate synthetic antimicrobials to overcome the current mechanism of resistance. Also, encourage in prudent use and misuse of antimicrobial agents. Thus, decline in treatment costs and in the rate of morbidity and mortality. This review will be concentrating on the mechanism of actions of several antibiotics and how bacteria develop resistance to them, as well as the method of acquiring the resistance in several bacteria and how can a strain be resistant to several types of antibiotics. This review also analyzes the prevalence, major clinical implications, clinical causes of antibiotic resistance. Further, it evaluates the global burden of antimicrobial resistance, identifies various challenges and strategies in addressing the issue. Finally, put forward certain recommendations to prevent the spread and reduce the rate of resistance growth.
Collapse
Affiliation(s)
- Manar Ali Abushaheen
- Department of Clinical Laboratory Science, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Muzaheed
- Department of Clinical Laboratory Science, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
| | - Amal Jamil Fatani
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Mohammed Alosaimi
- Consultant, Department of Restorative Dentistry, College of Dentistry, King Saud bin Abdul Aziz University for Health Sciences, P.O Box: 22490, Riyadh 11426, Saudi Arabia
| | - Wael Mansy
- Clinical Pharmacy Department, College of Pharmacy, King Saud University, Saudi Arabia; Pharmacology Department, Faculty of Medicine, Cairo University, Egypt
| | - Merin George
- General Dentist and Public Health Researcher, Australia
| | - Sadananda Acharya
- Department of Public Health, College of Public Health, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Sanjay Rathod
- Department of Post Graduate Studies and Research in Microbiology, Gulbarga University, Gulbarga- 585106, India
| | - Darshan Devang Divakar
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Chitra Jhugroo
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Sajith Vellappally
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Aftab Ahmed Khan
- Dental Biomaterials Research Chair, Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia
| | - Jilani Shaik
- Genome Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Poojdev Jhugroo
- CAP Research Ltd., 2nd Floor Orbis Court, 132 St Jean Road 72218 Quatre Bornes, Mauritius
| |
Collapse
|
5
|
Sicora CI, Chiș I, Chiș C, Sicora O. Regulation of PSII function in Cyanothece sp. ATCC 51142 during a light-dark cycle. PHOTOSYNTHESIS RESEARCH 2019; 139:461-473. [PMID: 30357676 DOI: 10.1007/s11120-018-0598-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
Cyanobacteria, as well as green algae and higher plants, have highly conserved photosynthetic machinery. Cyanothece sp. ATCC 51142 is a unicellular, aerobic, diazotrophic cyanobacterium that fixes N2 in the dark. In Cyanothece, the psbA gene family is composed of five members, encoding different isoforms of the D1 protein. A new D1 protein has been postulated in the literature, which blocks PSII during the night and allows the fixation of nitrogen. We present data showing changes in PSII function in cells grown in cycles alternating between 12 h of light and dark, respectively, at Cyanothece sp. ATCC 51142. Cyanothece sp. ATCC 51142 uses intrinsic mechanisms to protect its nitrogenase activity in a two-stage process. In Stage I, immediately after the onset of darkness, the cells lose photosynthetic activity in a reversible process, probably by dissociation of water oxidation complex from photosystem II via a mechanism that does not require de novo protein synthesis. In Stage II, a more severe disruption of photosystem II function occurs is in part protein synthesis dependent and it could be a functional signature of the presence of sentinel D1 in a limited number of reaction centers still active or not yet inactivated by the mechanism described in Stage I. This process of inhibition uses light as a triggering signal for both the inhibition of photosynthetic activity and recovery when light returns. The intrinsic mechanism of photosynthetic inactivation during darkness with the interplay of the two mechanisms requires further studies.
Collapse
Affiliation(s)
- Cosmin Ionel Sicora
- Biological Research Center Jibou, 16 Wesselenyi Street, 455200, Jibou, Sălaj, Romania.
| | - Iuliana Chiș
- Biological Research Center Jibou, 16 Wesselenyi Street, 455200, Jibou, Sălaj, Romania
| | - Ciprian Chiș
- Biological Research Center Jibou, 16 Wesselenyi Street, 455200, Jibou, Sălaj, Romania
| | - Oana Sicora
- Biological Research Center Jibou, 16 Wesselenyi Street, 455200, Jibou, Sălaj, Romania
| |
Collapse
|
6
|
Kirkpatrick JE, Kirkwood KL, Woster PM. Inhibition of the histone demethylase KDM4B leads to activation of KDM1A, attenuates bacterial-induced pro-inflammatory cytokine release, and reduces osteoclastogenesis. Epigenetics 2018; 13:557-572. [PMID: 29927684 PMCID: PMC6260135 DOI: 10.1080/15592294.2018.1481703] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 05/21/2018] [Indexed: 12/14/2022] Open
Abstract
Periodontal disease (PD) afflicts 46% of Americans with no effective adjunctive therapies available. While most pharmacotherapy for PD targets bacteria, the host immune response is responsible for driving tissue damage and bone loss in severe disease. Herein, we establish that the histone demethylase KDM4B is a potential drug target for the treatment of PD. Immunohistochemical staining of diseased periodontal epithelium revealed an increased abundance of KDM4B that correlates with inflammation. In murine calvarial sections exposed to Aggregatibacter actinomycetemcomitans lipopolysaccharide (Aa-LPS), immunohistochemical staining revealed a significant increase in KDM4B protein expression. The 8-hydroxyquinoline ML324 is known to inhibit the related demethylase KDM4E in vitro, but has not been evaluated against any other targets. Our studies indicate that ML324 also inhibits KDM4B (IC50: 4.9 μM), and decreases the pro-inflammatory cytokine response to an Aa-LPS challenge in vitro. Our results suggest that KDM4B inhibition-induced immunosuppression works indirectly, requiring new protein synthesis. In addition, fluorescence-stained macrophages exhibited a significant decrease in global monomethyl histone 3 lysine 4 (H3K4me) levels following an Aa-LPS challenge that was prevented by KDM4B inhibition, suggesting this effect is produced through KDM1A-mediated demethylation of H3K4. Finally, ML324 inhibition of KDM4B in osteoclast progenitors produced a significant reduction in Aa-LPS-induced osteoclastogenesis. These data link histone methylation with host immune response to bacterial pathogens in PD, and suggest a previously unreported, alternative mechanism for epigenetic control of the host inflammatory environment. As such, KDM4B represents a new therapeutic target for treating hyper-inflammatory diseases that result in bone destruction.
Collapse
Affiliation(s)
- Joy E. Kirkpatrick
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | | | - Patrick M. Woster
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| |
Collapse
|
7
|
Singh R, Williams J, Vince R. Puromycin based inhibitors of aminopeptidases for the potential treatment of hematologic malignancies. Eur J Med Chem 2017; 139:325-336. [PMID: 28803047 DOI: 10.1016/j.ejmech.2017.07.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 07/14/2017] [Accepted: 07/22/2017] [Indexed: 02/01/2023]
Abstract
Substantial progress has been described in the study of puromycin and its analogs for antibiotic properties. However, the peptidase inhibitory activity of related analogs has not been explored as extensively. Specifically, inhibiting aminopeptidases for achieving antitumor effect has been sparsely investigated. Herein, we address this challenge by reporting the synthesis of a series of analogs based on the structural template of puromycin. We also present exhaustive biochemical and in vitro analyses in support of our thesis. Analyzing the structure-activity relationship revealed a steric requirement for maximum potency. Effective inhibitors of Puromycin-Sensitive Aminopeptidase (PSA) are disclosed here. These potential therapeutic agents display superior in vitro antitumor potency against two leukemic cell lines, as compared to known inhibitors of aminopeptidases.
Collapse
Affiliation(s)
- Rohit Singh
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Jessica Williams
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Robert Vince
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA.
| |
Collapse
|
8
|
Lau CHF, Krahn T, Gilmour C, Mullen E, Poole K. AmgRS-mediated envelope stress-inducible expression of the mexXY multidrug efflux operon of Pseudomonas aeruginosa. Microbiologyopen 2014; 4:121-35. [PMID: 25450797 PMCID: PMC4335980 DOI: 10.1002/mbo3.226] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 10/27/2014] [Accepted: 11/03/2014] [Indexed: 01/07/2023] Open
Abstract
AmgRS is an envelope stress-responsive two-component system and aminoglycoside resistance determinant in Pseudomonas aeruginosa that is proposed to protect cells from membrane damage caused by aminoglycoside-generated mistranslated polypeptides. Consistent with this, a ΔamgR strain showed increased aminoglycoside-promoted membrane damage, damage that was largely absent in AmgRS-activated amgS-mutant strains. Intriguingly, one such mutation, V121G, while providing for enhanced resistance to aminoglycosides, rendered P. aeruginosa susceptible to several ribosome-targeting nonaminoglycoside antimicrobials that are inducers and presumed substrates of the MexXY-OprM multidrug efflux system. Surprisingly, the amgSV 121G mutation increased mexXY expression threefold, suggesting that export of these nonaminoglycosides was compromised in the amgSV 121G mutant. Nonetheless, a link was established between AmgRS activation and mexXY expression and this was confirmed in studies showing that aminoglycoside-promoted mexXY expression is dependent on AmgRS. While nonaminoglycosides also induced mexXY expression, this was not AmgRS-dependent, consistent with these agents not generating mistranslated polypeptides and not activating AmgRS. The aminoglycoside inducibility of mexXY was abrogated in a mutant lacking the AmgRS target genes htpX and PA5528, encoding a presumed cytoplasmic membrane-associated protease and a membrane protein of unknown function, respectively. Thus, aminoglycoside induction of mexXY is a response to membrane damage and activation of the AmgRS two-component system.
Collapse
Affiliation(s)
- Calvin Ho-Fung Lau
- Department of Biomedical and Molecular Sciences, Botterell Hall, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
| | | | | | | | | |
Collapse
|
9
|
Hong W, Zeng J, Xie J. Antibiotic drugs targeting bacterial RNAs. Acta Pharm Sin B 2014; 4:258-65. [PMID: 26579393 PMCID: PMC4629089 DOI: 10.1016/j.apsb.2014.06.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/04/2014] [Accepted: 06/20/2014] [Indexed: 10/26/2022] Open
Abstract
RNAs have diverse structures that include bulges and internal loops able to form tertiary contacts or serve as ligand binding sites. The recent increase in structural and functional information related to RNAs has put them in the limelight as a drug target for small molecule therapy. In addition, the recognition of the marked difference between prokaryotic and eukaryotic rRNA has led to the development of antibiotics that specifically target bacterial rRNA, reduce protein translation and thereby inhibit bacterial growth. To facilitate the development of new antibiotics targeting RNA, we here review the literature concerning such antibiotics, mRNA, riboswitch and tRNA and the key methodologies used for their screening.
Collapse
Affiliation(s)
| | | | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing 400715, China
| |
Collapse
|
10
|
Differential effect of the alkaloid lycorine on rho (+), mit (-), rho (-), and rho (o) strains of Saccharomyces cerevisiae. Curr Genet 2013; 8:493-8. [PMID: 24177949 DOI: 10.1007/bf00410435] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/1984] [Indexed: 10/26/2022]
Abstract
The alkaloid lycorine inhibits growth of rho (+), mit (-), and rho (-) strains, whereas rho (0) strains (devoid of mitochondrial DNA) of Saccharomyces cerevisiae are resistant to high concentrations of the drug. The inhibitory effect of lycorine on the growth of rho (+) strains can be counteracted by the addition of ascorbic acid to the plating medium. Lycorine induces cytoplasmic respiratory deficient mutants upon growth in glucose complete medium containing the alkaloid. The minimal inhibitory concentration of lycorine in glucose complete medium is ten times higher than in glycerol complete medium, thus demonstrating its preferential action on mitochondrial functions. Total protein synthesis and mitochondrial protein synthesis are only slightly inhibited by lycorine. It has, however, an inhibitory effect on DNA and RNA synthesis.
Collapse
|
11
|
Minami R, Hayakawa A, Kagawa H, Yanagi Y, Yokosawa H, Kawahara H. BAG-6 is essential for selective elimination of defective proteasomal substrates. ACTA ACUST UNITED AC 2010; 190:637-50. [PMID: 20713601 PMCID: PMC2928017 DOI: 10.1083/jcb.200908092] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BAG-6/Scythe/BAT3 is a ubiquitin-like protein that was originally reported to be the product of a novel gene located within the human major histocompatibility complex, although the mechanisms of its function remain largely obscure. Here, we demonstrate the involvement of BAG-6 in the degradation of a CL1 model defective protein substrate in mammalian cells. We show that BAG-6 is essential for not only model substrate degradation but also the ubiquitin-mediated metabolism of newly synthesized defective polypeptides. Furthermore, our in vivo and in vitro analysis shows that BAG-6 interacts physically with puromycin-labeled nascent chain polypeptides and regulates their proteasome-mediated degradation. Finally, we show that knockdown of BAG-6 results in the suppressed presentation of MHC class I on the cell surface, a procedure known to be affected by the efficiency of metabolism of defective ribosomal products. Therefore, we propose that BAG-6 is necessary for ubiquitin-mediated degradation of newly synthesized defective polypeptides.
Collapse
Affiliation(s)
- Ryosuke Minami
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
12
|
Näslund J, Nascimento FJA, Gunnarsson JS. Meiofauna reduces bacterial mineralization of naphthalene in marine sediment. ISME JOURNAL 2010; 4:1421-30. [DOI: 10.1038/ismej.2010.63] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
13
|
Nikonov AV, Hauri HP, Lauring B, Kreibich G. Climp-63-mediated binding of microtubules to the ER affects the lateral mobility of translocon complexes. J Cell Sci 2007; 120:2248-58. [PMID: 17567679 DOI: 10.1242/jcs.008979] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microtubules are frequently seen in close proximity to membranes of the endoplasmic reticulum (ER), and the membrane protein CLIMP-63 is thought to mediate specific interaction between these two structures. It was, therefore, of interest to investigate whether these microtubules are in fact responsible for the highly restricted lateral mobility of the translocon complexes in M3/18 cells as described before. As determined by fluorescence recovery after photobleaching, the breakdown of microtubules caused by drug treatment or by overexpression of the microtubule-severing protein spastin, resulted in an increased lateral mobility of the translocons that are assembled into polysomes. Also, the expression of a CLIMP-63 mutant lacking the microtubule-binding domain resulted in a significant increase of the lateral mobility of the translocon complexes. The most striking increase in the diffusion rate of the translocon complexes was observed in M3/18 cells transfected with a siRNA that effectively knocked down the expression of the endogenous CLIMP-63. It appears, therefore, that interaction of microtubules with the ER results in the immobilization of translocon complexes that are part of membrane-bound polysomes, and may play a role in the mechanism that segregates the rough and smooth domains of the ER.
Collapse
Affiliation(s)
- Andrei V Nikonov
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | | | | | | |
Collapse
|
14
|
Muller JF, Stevens AM, Craig J, Love NG. Transcriptome analysis reveals that multidrug efflux genes are upregulated to protect Pseudomonas aeruginosa from pentachlorophenol stress. Appl Environ Microbiol 2007; 73:4550-8. [PMID: 17526777 PMCID: PMC1932803 DOI: 10.1128/aem.00169-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Through chemical contamination of natural environments, microbial communities are exposed to many different types of chemical stressors; however, research on whole-genome responses to this contaminant stress is limited. This study examined the transcriptome response of a common soil bacterium, Pseudomonas aeruginosa, to the common environmental contaminant pentachlorophenol (PCP). Cells were grown in chemostats at a low growth rate to obtain substrate-limited, steady-state, balanced-growth conditions. The PCP stress was administered as a continuous increase in concentration, and samples taken over time were examined for physiological function changes with whole-cell acetate uptake rates (WAURs) and cell viability and for gene expression changes by Affymetrix GeneChip technology and real-time reverse transcriptase PCR. Cell viability, measured by heterotrophic plate counts, showed a moderately steady decrease after exposure to the stressor, but WAURs did not change in response to PCP. In contrast to the physiological data, the microarray data showed significant changes in the expression of several genes. In particular, genes coding for multidrug efflux pumps, including MexAB-OprM, were strongly upregulated. The upregulation of these efflux pumps protected the cells from the potentially toxic effects of PCP, allowing the physiological whole-cell function to remain constant.
Collapse
Affiliation(s)
- Jocelyn Fraga Muller
- Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | | | | | | |
Collapse
|
15
|
Protein synthesis inhibition as a potential strategy for metabolic down-regulation. Resuscitation 2007; 73:296-303. [PMID: 17250947 DOI: 10.1016/j.resuscitation.2006.08.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2005] [Revised: 08/18/2006] [Accepted: 08/18/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE This pilot study tested the potential of puromycin (PUR) to inhibit protein synthesis and reduce oxygen utilization in a non-hibernating, whole animal preparation. METHODS After anesthesia and instrumentation, male rats received a single dose of PUR or 0.9% saline (control), followed 60 min later with [(35)S] methionine/cysteine radiolabeling. Thirty minutes after isotope injection, organ biopsies were taken for quantification of de novo protein synthesis. Arterial and central venous blood gases were obtained at baseline and 60 min after injection of PUR or 0.9% saline. Temperature, mean arterial pressure (MAP), and heart rate were recorded continuously. RESULTS Animals receiving PUR demonstrated significant reductions in protein synthesis in all organ systems sampled (p<0.05). The overall reduction averaged 67.8%. Central venous oxygen saturations (S(cv)O(2)) were higher in the PUR group than the controls at 60 min (90+/-2% versus 80+/-4%, p<0.05). The oxygen extraction ratio (O(2)ER) decreased from 16.1+/-1.7% to 6.8+/-1.2% in the PUR group (p<0.05) and increased from 12.5+/-3.2% to 16.0+/-4.2% in the controls (p=0.44). There was no difference in temperature, MAP, heart rate or blood gas variables, other than S(cv)O(2), at baseline or 60 min between groups. CONCLUSIONS These results demonstrate that PUR is capable of reducing whole body protein synthesis significantly within a relatively short duration of time. This appears to decrease whole body oxygen utilization as evidenced by an increase in S(cv)O(2) and a decrease in O(2)ER. Protein synthesis inhibition may reduce metabolic demands and should be tested for its potential to improve outcomes where oxygen demands exceed oxygen delivery.
Collapse
|
16
|
Desrosiers M, Planas D, Mucci A. Mercury methylation in the epilithon of boreal shield aquatic ecosystems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:1540-6. [PMID: 16568768 DOI: 10.1021/es0508828] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Methylation rates by periphyton growing on the rocky shore of a remote boreal shield lake were measured over diurnal cycles at temperatures representative of summer and fall conditions. The measurements were carried out in vitro with natural communities grown on artificial Teflon substrates submerged along the lake's shore for 1-2 years. At temperatures above 20 degrees C, epilithon Hg methylation rates were fast and reached a steady state within 12 h upon exposure to 2 ng L(-1) of inorganic mercury. A variety of inhibitors were used to identify which microorganisms in the epilithic biofilm are responsible for the methylation. The addition of molybdate, which is believed to suppress the activity of sulfate-reducing bacteria, decreased methylmercury production rates by 60% in both light and dark experiments. The prokaryote inhibitor chloramphenicol reduced the methylation rate by 40% only during dark periods whereas an algal inhibitor (DCMU), which suppresses photosynthesis, decreased the methylation rate by 60% during light periods. Results of this study reveal that epilithon communities may be a significant source of MeHg to higher aquatic organisms in lakes and that the integrity of the epilithic biofilm is important for its ability to methylate Hg.
Collapse
Affiliation(s)
- Mélanie Desrosiers
- GEOTOP/UQAM/McGill Université du Québec a Montréal, C. P. 8888, Succursale Centre Ville, Montréal, Québec, Canada H3C 3P8
| | | | | |
Collapse
|
17
|
Del Giudice L, Massardo DR, Pontieri P, Wolf K. Interaction between yeast mitochondrial and nuclear genomes: null alleles of RTG genes affect resistance to the alkaloid lycorine in rho0 petites of Saccharomyces cerevisiae. Gene 2005; 354:9-14. [PMID: 15893890 DOI: 10.1016/j.gene.2005.03.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 01/23/2005] [Accepted: 03/23/2005] [Indexed: 10/25/2022]
Abstract
Some nuclear genes in Saccharomyces cerevisiae (S. cerevisiae) respond to signals from the mitochondria in a process called by Butow (Cell Death Differ. 9 (2002) 1043-1045) retrograde regulation. Expression of these genes is activated in cells lacking mitochondrial function by involvement of RTG1, RTG2 and RTG3 genes whose protein products bind to "R-boxes" in the promoter region; RTG2p is a cytoplasmic protein. Since S. cerevisiae rho0 strains, lacking the entire mitochondrial genome, are resistant to lycorine, an alkaloid extracted from Amaryllis plants, it could be hypothesized that in rho0 cells the dysfunctional mitochondrial status stimulates overexpression of nuclear genes very likely involved in both nuclear and mitochondrial DNA replication. In this report we show that the resistance of rho0 cells to lycorine is affected by the deletion of RTG genes.
Collapse
Affiliation(s)
- Luigi Del Giudice
- Istituto di Genetica e Biofisica Adriano Buzzati-Traverso, Consiglio Nazionale delle Ricerche, Napoli, Italy.
| | | | | | | |
Collapse
|
18
|
Abstract
The study of the cell biology of antigen processing and presentation has greatly contributed to our understanding of the immune response. The work of many immunologically inclined cell biologists has also permitted new insights into cellular mechanisms shared by many cell types. Here are described recent and particularly exciting findings on the regulation of major histocompatibility complex class I-restricted presentation in dendritic cells and their contribution to the deciphering of the cellular response to pathogen detection.
Collapse
Affiliation(s)
- Philippe Pierre
- Center d'Immunologie de Marseille-Luminy, CNRS-INSERM-Université de la Meditérannée, Campus de Luminy, Marseille, France.
| |
Collapse
|
19
|
Foloppe N, Chen IJ, Davis B, Hold A, Morley D, Howes R. A structure-based strategy to identify new molecular scaffolds targeting the bacterial ribosomal A-site. Bioorg Med Chem 2004; 12:935-47. [PMID: 14980606 DOI: 10.1016/j.bmc.2003.12.023] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Accepted: 12/16/2003] [Indexed: 01/05/2023]
Abstract
The need for novel antibiotics is widely recognized. A well validated target of antibiotics is the bacterial ribosome. Recent X-ray structures of the ribosome bound to antibiotics have shed new light on the binding sites of these antibiotics, providing fresh impetus for structure-based strategies aiming at identifying new ribosomal ligands. In that respect, the ribosomal decoding region of the aminoacyl-tRNA acceptor site (A-site) is of particular interest because oligonucleotide model systems of this site are available for crystallography, NMR and compound binding assays. This work presents how these different resources can be combined in a hierarchical screening strategy which has led to the identification of new A-site ligands. The approach exploits an X-ray structure of the A-site against which large and diverse libraries of compounds were computationally docked. The complementarity of the compounds to the A-site was assessed using a scoring function specifically calibrated for RNA targets. Starting from approximately 1 million compounds, the computational selection of candidate ligands allowed us to focus the experimental work on 129 compounds, 34 of which showed affinity for the A-site in a FRET-based binding assay. NMR experiments confirmed binding to the A-site for some compounds. For the most potent compound in the FRET assay, a tentative binding mode is suggested, which is compatible with the NMR data and the limited SAR in this series. Overall, the results validate the screening strategy.
Collapse
Affiliation(s)
- Nicolas Foloppe
- Vernalis (R&D) Ltd, Granta Park, Abington, Cambridge CB1 6GB, UK.
| | | | | | | | | | | |
Collapse
|
20
|
Lelouard H, Ferrand V, Marguet D, Bania J, Camosseto V, David A, Gatti E, Pierre P. Dendritic cell aggresome-like induced structures are dedicated areas for ubiquitination and storage of newly synthesized defective proteins. ACTA ACUST UNITED AC 2004; 164:667-75. [PMID: 14981091 PMCID: PMC2172164 DOI: 10.1083/jcb.200312073] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control antigen processing and presentation. One of these mechanisms is the sorting of polyubiquitinated proteins in large cytosolic aggregates called dendritic cell aggresome-like induced structures (DALIS). DALIS formation and maintenance are tightly linked to protein synthesis. Here, we took advantage of an antibody recognizing the antibiotic puromycin to follow the fate of improperly translated proteins, also called defective ribosomal products (DRiPs). We demonstrate that DRiPs are rapidly stored and protected from degradation in DALIS. In addition, we show that DALIS contain the ubiquitin-activating enzyme E1, the ubiquitin-conjugating enzyme E225K, and the COOH terminus of Hsp70-interacting protein ubiquitin ligase. The accumulation of these enzymes in the central area of DALIS defines specific functional sites where initial DRiP incorporation and ubiquitination occur. Therefore, DCs are able to regulate DRiP degradation in response to pathogen-associated motifs, a capacity likely to be important for their immune functions.
Collapse
Affiliation(s)
- Hugues Lelouard
- Centre d'Immunologie de Marseille-Luminy, CNRS-INSERM-Université de la Méditerranée, Parc Scientifique de Luminy case 906, 13288 Marseille Cedex 09, France
| | | | | | | | | | | | | | | |
Collapse
|
21
|
|
22
|
Reis SA, Costa LV, Cavalcanti EDC, Giambiagi-deMarval M, Semêdo LTAS, Coelho RRR, Moussatché N, Damaso CRA. Protein synthesis inhibitory activity in culture filtrates from new strains of Streptomyces isolated from Brazilian tropical soils. Lett Appl Microbiol 2003; 37:138-43. [PMID: 12859656 DOI: 10.1046/j.1472-765x.2003.01363.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To investigate the effect of the culture supernatants from three newly isolated Streptomyces strains, 221, 235 and 606 on eukaryotic cells. METHODS AND RESULTS Cell lines were treated with the culture filtrates and assayed for protein synthesis by metabolic labelling, followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis. RNA synthesis was investigated by [5-3H]uridine incorporation. The three culture filtrates presented a strong inhibitory activity, reducing total protein synthesis of different eukaryotic cell lines by more than 85%. No effect on cellular RNA synthesis was detected. The culture filtrates did not affect the growth of the prokaryotic cells tested. CONCLUSIONS These new Streptomyces strains, recently isolated from Brazilian tropical soils, produce molecule(s) with inhibitory activity specific to eukaryote protein synthesis. SIGNIFICANCE AND IMPACT OF THE STUDY Streptomyces strains 221, 235 and 606, probably representing new species, might produce new bioactive compound(s), and can be used as valuable tools to study the protein synthesis pathway in eukaryotes.
Collapse
Affiliation(s)
- S A Reis
- Laboratório de Biologia Molecular de Vírus, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Choi J, Xu Z, Ou JH. Triple decoding of hepatitis C virus RNA by programmed translational frameshifting. Mol Cell Biol 2003; 23:1489-97. [PMID: 12588970 PMCID: PMC151691 DOI: 10.1128/mcb.23.5.1489-1497.2003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2002] [Revised: 08/21/2002] [Accepted: 11/27/2002] [Indexed: 11/20/2022] Open
Abstract
Ribosomes can be programmed to shift from one reading frame to another during translation. Hepatitis C virus (HCV) uses such a mechanism to produce F protein from the -2/+1 reading frame. We now report that the HCV frameshift signal can mediate the synthesis of the core protein of the zero frame, the F protein of the -2/+1 frame, and a 1.5-kDa protein of the -1/+2 frame. This triple decoding function does not require sequences flanking the frameshift signal and is apparently independent of membranes and the synthesis of the HCV polyprotein. Two consensus -1 frameshift sequences in the HCV type 1 frameshift signal facilitate ribosomal frameshifts into both overlapping reading frames. A sequence which is located immediately downstream of the frameshift signal and has the potential to form a double stem-loop structure can significantly enhance translational frameshifting in the presence of the peptidyl-transferase inhibitor puromycin. Based on these results, a model is proposed to explain the triple decoding activities of the HCV ribosomal frameshift signal.
Collapse
Affiliation(s)
- Jinah Choi
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
| | | | | |
Collapse
|
24
|
Walter F, Pütz J, Giegé R, Westhof E. Binding of tobramycin leads to conformational changes in yeast tRNA(Asp) and inhibition of aminoacylation. EMBO J 2002; 21:760-8. [PMID: 11847123 PMCID: PMC125865 DOI: 10.1093/emboj/21.4.760] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aminoglycosides inhibit translation in bacteria by binding to the A site in the ribosome. Here, it is shown that, in yeast, aminoglycosides can also interfere with other processes of translation in vitro. Steady-state aminoacylation kinetics of unmodified yeast tRNA(Asp) transcript indicate that the complex between tRNA(Asp) and tobramycin is a competitive inhibitor of the aspartylation reaction with an inhibition constant (K(I)) of 36 nM. Addition of an excess of heterologous tRNAs did not reverse the charging of tRNA(Asp), indicating a specific inhibition of the aspartylation reaction. Although magnesium ions compete with the inhibitory effect, the formation of the aspartate adenylate in the ATP-PP(i) exchange reaction by aspartyl-tRNA synthetase in the absence of the tRNA is not inhibited. Ultraviolet absorbance melting experiments indicate that tobramycin interacts with and destabilizes the native L-shaped tertiary structure of tRNA(Asp). Fluorescence anisotropy using fluorescein-labelled tobramycin reveals a stoichiometry of one molecule bound to tRNA(Asp) with a K(D) of 267 nM. The results indicate that aminoglycosides are biologically effective when their binding induces a shift in a conformational equilibrium of the RNA.
Collapse
Affiliation(s)
| | | | | | - Eric Westhof
- UPR 9002 du CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, F-67084 Strasbourg Cedex, France
Corresponding author e-mail:
| |
Collapse
|
25
|
Job C, Eberwine J. Identification of sites for exponential translation in living dendrites. Proc Natl Acad Sci U S A 2001; 98:13037-42. [PMID: 11606784 PMCID: PMC60820 DOI: 10.1073/pnas.231485698] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuronal processes contain mRNAs and membrane structures, and some forms of synaptic plasticity seem to require protein synthesis in dendrites of hippocampal neurons. To quantitate dendritic protein synthesis, we used multiphoton microscopy of green fluorescent protein synthesized in living isolated dendrites. Transfection of dendrites with mRNA encoding green fluorescent protein resulted in fluorescence that exponentially increased on stimulation with a glutamate receptor agonist; a reaction attenuated by the translation inhibitors anisomycin and emetine. Comparable experiments on whole neurons revealed that (RS)-3,5-dihydroxy-phenylglycine 0.5 H(2)O (DHPG)-stimulated fluorescence was linear in cell bodies relative to the exponential increase seen in dendrites. Detailed spatial analysis of the subdendritic distribution of fluorescence revealed "hotspots," sites of dendritic translation that were spatially stable. However, detailed temporal analysis of these hotspots revealed heterogeneous rates of translation. A double-label protocol counterstaining for ribosomes indicated that sites of "fastest" translation correlated with increased ribosome density, consistent with ribosome subunit assembly for initiation, the first step of translation. We propose that dendrites have specific sites specialized for fast translation.
Collapse
Affiliation(s)
- C Job
- Department of Pharmacology, University of Pennsylvania Medical Center, Philadelphia, PA 19104-6058, USA
| | | |
Collapse
|
26
|
Iouk TL, Aitchison JD, Maguire S, Wozniak RW. Rrb1p, a yeast nuclear WD-repeat protein involved in the regulation of ribosome biosynthesis. Mol Cell Biol 2001; 21:1260-71. [PMID: 11158312 PMCID: PMC99579 DOI: 10.1128/mcb.21.4.1260-1271.2001] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ribosome biogenesis is regulated by environmental cues that coordinately modulate the synthesis of ribosomal components and their assembly into functional subunits. We have identified an essential yeast WD-repeat-containing protein, termed Rrb1p, that has a role in both the assembly of the 60S ribosomal subunits and the transcriptional regulation of ribosomal protein (RP) genes. Rrb1p is located in the nucleus and is concentrated in the nucleolus. Its presence is required to maintain normal cellular levels of 60S subunits, 80S ribosomes, and polyribosomes. The function of Rrb1p in ribosome biogenesis appears to be linked to its association with the ribosomal protein rpL3. Immunoprecipitation of Rrb1p from nuclear extracts revealed that it physically interacts with rpL3. Moreover, the overproduction of Rrb1p led to increases in cellular levels of free rpL3 that accumulated in the nucleus together with Rrb1p. The concentration of these proteins within the nucleus was dependent on ongoing protein translation. We also showed that overexpression of RRB1 led to an increase in the expression of RPL3 while all other examined RP genes were unaffected. In contrast, depletion of RRB1 caused an increase in the expression of all RP genes examined except RPL3. These results suggest that Rrb1p regulates RPL3 expression and uncouples it from the coordinated expression of other RP genes.
Collapse
Affiliation(s)
- T L Iouk
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | | | | | | |
Collapse
|
27
|
Brodersen DE, Clemons WM, Carter AP, Morgan-Warren RJ, Wimberly BT, Ramakrishnan V. The structural basis for the action of the antibiotics tetracycline, pactamycin, and hygromycin B on the 30S ribosomal subunit. Cell 2000; 103:1143-54. [PMID: 11163189 DOI: 10.1016/s0092-8674(00)00216-6] [Citation(s) in RCA: 604] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have used the recently determined atomic structure of the 30S ribosomal subunit to determine the structures of its complexes with the antibiotics tetracycline, pactamycin, and hygromycin B. The antibiotics bind to discrete sites on the 30S subunit in a manner consistent with much but not all biochemical data. For each of these antibiotics, interactions with the 30S subunit suggest a mechanism for its effects on ribosome function.
Collapse
Affiliation(s)
- D E Brodersen
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
| | | | | | | | | | | |
Collapse
|
28
|
Thor P. Relationship between specific dynamic action and protein deposition in calanoid copepods. JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 2000; 245:171-182. [PMID: 10699208 DOI: 10.1016/s0022-0981(99)00159-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The link between specific dynamic action (SDA) and protein deposition was investigated in copepodites stage V of two calanoid copepod species, the neritic Acartia tonsa and the oceanic Calanus finmarchicus. This was done by measuring respiration before, during, and after a specific feeding period and measuring the incorporation of carbon into proteins. These were also measured on individuals incubated with cycloheximide, an antibiotic that inhibits protein synthesis. The cycloheximide treatment significantly diminished the magnitude of SDA in both A. tonsa and C. finmarchicus, and inhibited carbon incorporation into protein in both species. This provides evidence that the rate at which protein deposition takes place greatly affects the magnitude of SDA. The specific respiration rates of both starving and feeding copepods were generally higher in A. tonsa than in C. finmarchicus. This influenced SDA, the magnitude of SDA normalised to an 8 h feeding period being threefold higher in A. tonsa (78.7+/-25.7 nlO(2) µgC(-1)) than in C. finmarchicus (27.5+/-11.6 nlO(2) µgC(-1)). This difference may arise due to differences in energy allocation in the organisms of the copepodite V stage of the two species. In this stage C. finmarchicus deposits large quantities of storage lipids, predominately wax esters, whereas A. tonsa deposits proteins during somatic growth.
Collapse
Affiliation(s)
- P Thor
- Department of Life Sciences and Chemistry, Roskilde University, PO Box 260, DK-4000, Roskilde, Denmark
| |
Collapse
|
29
|
Beidler DR, Ahuja D, Wicha MS, Toogood PL. Inhibition of protein synthesis by didemnin B is not sufficient to induce apoptosis in human mammary carcinoma (MCF7) cells. Biochem Pharmacol 1999; 58:1067-74. [PMID: 10509759 DOI: 10.1016/s0006-2952(99)00193-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Didemnin B (DB) is one member of a class of natural cyclic depsipeptides that display potent cytotoxicity in vitro. The detailed mechanism of action of DB is unknown, although it appears to involve the inhibition of protein biosynthesis. Additional activities of DB have established DB as a rapid and potent inducer of apoptosis in HL-60 cells. Our aim was to determine if the induction of apoptosis by DB is mediated through inhibition of protein synthesis in MCF-7 human breast carcinoma cells. Apoptosis was observed only at > or = 100 nM DB, even though inhibition of protein synthesis occurred at much lower DB concentrations (IC50 = 12 nM). DB-induced apoptosis was mediated by caspase activation, since cleavage of the caspase substrate poly(ADPribose) polymerase was observed as early as 6 hr after DB exposure. Two additional protein synthesis inhibitors, cycloheximide (CHX) and emetine (ET), failed to induce apoptosis at concentrations that completely inhibited protein synthesis. Moreover, DB-induced apoptosis was enhanced only slightly by pre- and co-treatment with CHX and ET. Thus, inhibition of protein synthesis alone was not sufficient to induce apoptosis in these cells. As a measure of antiproliferative potential, DB (1-5 nM) inhibited the colony forming ability of MCF7 cells regardless of pretreatment with CHX. In conclusion, additional effects of DB, independent of protein synthesis inhibition, are proposed to account for its ability to induce apoptosis and prevent cell proliferation.
Collapse
Affiliation(s)
- D R Beidler
- Department of Internal Medicine and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor 48109-0946, USA.
| | | | | | | |
Collapse
|
30
|
Gerbaux C, Van Bambeke F, Montenez JP, Piret J, Morlighem G, Tulkens PM. Hyperactivity of cathepsin B and other lysosomal enzymes in fibroblasts exposed to azithromycin, a dicationic macrolide antibiotic with exceptional tissue accumulation. FEBS Lett 1996; 394:307-10. [PMID: 8830663 DOI: 10.1016/0014-5793(96)00975-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Azithromycin accumulates in lysosomes where it causes phospholipidosis. In homogenates prepared by sonication of fibroblasts incubated for 3 days with azithromycin (66 microM), the activities of sulfatase A, phospholipase A1, N-acetyl-beta-hexosaminidase and cathepsin B increased from 180 to 330%, but not those of 3 non-lysosomal enzymes. The level of cathepsin B mRNA was unaffected. The hyperactivity induced by azithromycin is non-reversible upon drug withdrawal, prevented by coincubation with cycloheximide, affects the Vmax but not the Km, and is not reproduced with gentamicin, another drug also causing lysosomal phospholipidosis. The data therefore suggest that azithromycin increases the level of lysosomal enzymes by a mechanism distinct from the stimulation of gene expression but requiring protein synthesis, and is not in direct relation to the lysosomal phospholipidosis.
Collapse
Affiliation(s)
- C Gerbaux
- Unité de Pharmacologie Cellulaire et Moléculaire, Université Catholique de Louvain, Bruxelles, Belgium.
| | | | | | | | | | | |
Collapse
|
31
|
Abstract
The translational activity of more than 40 different mRNAs in rodent testes has been analyzed by determining the proportions of inactive free-mRNPs and active polysomal mRNAs in sucrose gradients. These mRNAs can be sorted into several groups comprising mRNAs with similar patterns of translational activity in particular cell types. mRNAs in testicular somatic cells sediment primarily with polysomes, indicating that they are translated efficiently, whereas the vast majority of mRNAs in late meiotic and haploid spermatogenic cells display high levels of free-mRNAPs, indicative of a block to the initiation of translation. Protamine mRNAs exemplify a group of mRNAs that is transcribed in round spermatids, stored as free-mRNPs for several days, and translated in elongated spermatids after the cessation of transcription. The extent to which the free-mRNPs in primary spermatocytes and round spermatids are due to developmental changes in translational activity is unclear. mRNAs at these stages can often be detected earlier than the corresponding protein, implicating either a delay in translational activation or difficulties in detecting the protein. In contrast, sucrose gradients consistently indicate little difference in the proportions of various mRNAs in free-mRNPs in primary spermatocytes and round spermatids, implying that the proportions of translationally active mRNAs remain essentially constant. Since the levels of some mRNAs appear to greatly exceed the amount that is translated, the biological significance of some free-mRNPs in meiotic and early haploid cells in unclear. There are numerous examples of controls over the translation of individual mRNAs in meiotic and haploid cells; the proportions of various mRNAs in free-mRNPs range from virtually none to virtually all, and individual mRNAs are activated at specific stages in elongated spermatids. Existing evidence is contradictory whether the mRNAs in the protamine/transition protein gene family are repressed by mRNP proteins of sequestration.
Collapse
Affiliation(s)
- K C Kleene
- Department of Biology, University of Massachusetts at Boston 02125-3393, USA
| |
Collapse
|
32
|
Montenez JP, Delaissé JM, Tulkens PM, Kishore BK. Increased activities of cathepsin B and other lysosomal hydrolases in fibroblasts and bone tissue cultured in the presence of cysteine proteinases inhibitors. Life Sci 1994; 55:1199-208. [PMID: 7934617 DOI: 10.1016/0024-3205(94)00659-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Leupeptin is an established, reversible inhibitor of cathepsin B, a lysosomal cysteine proteinase. Yet, in rat fibroblasts as well as in foetal mouse calvaria, we observed an increase of the activity of cathepsin B in homogenates of cells and tissue harvested after culture in the presence of leupeptin. This effect was also seen for other lysosomal hydrolases, namely sphingomyelinase, N-acetyl-beta-glucosaminidase, arylsulphatase A and phospholipase A1 in fibroblasts, and beta-glucuronidase in mouse calvaria. In calvaria, antipain, another reversible cysteine proteinase inhibitor, caused a similar effect, whereas E-64, an irreversible inhibitor, was consistently inhibitory of the cathepsin B activity; yet it also caused an increase of beta-glucuronidase activity. The effect of leupeptin in fibroblasts was dose and time-dependent, required the continuous presence of the inhibitor, and was not dependent from protein synthesis. Actually, addition of cycloheximide caused a severe loss of activity of cathepsin B and of sphingomyelinase. In the presence of both cycloheximide and leupeptin, however, these two activities were retained to a value corresponding to that found in excess in cells cultivated with leupeptin alone. The data therefore suggests that leupeptin exerts the effects described in this paper by preventing the degradation of cathepsin B, sphingomyelinase and probably several other lysosomal hydrolases by cysteine proteinases. We therefore propose that cysteine proteinases play a key role in the control of the steady-state levels of these enzymes in normal conditions.
Collapse
Affiliation(s)
- J P Montenez
- Laboratoire de Chimie Physiologique (Groupe de Pharmacologie Cellulaire et Moléculaire, Université Catholique de Louvain, Brussels, Belgium
| | | | | | | |
Collapse
|
33
|
Kleiman R, Banker G, Steward O. Inhibition of protein synthesis alters the subcellular distribution of mRNA in neurons but does not prevent dendritic transport of RNA. Proc Natl Acad Sci U S A 1993; 90:11192-6. [PMID: 8248226 PMCID: PMC47948 DOI: 10.1073/pnas.90.23.11192] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
This study evaluates whether protein synthesis plays a role in targeting RNA molecules to different subcellular domains within neurons. Transport of newly synthesized RNA (labeled with [3H]uridine) was examined in the presence of the protein synthesis inhibitors puromycin and cycloheximide. In situ hybridization was used to determine whether inhibition of protein synthesis altered the subcellular distribution of mRNAs. Transport of recently synthesized RNA was not disrupted after prolonged exposure to either inhibitor. However, inhibition of protein synthesis caused several mRNAs that are normally confined to the cell body to appear in dendrites. The distribution of mRNAs that are normally present in dendrites was unaffected. These findings suggest that protein synthesis is not required to translocate RNA into the dendrites but may play a role in restricting particular mRNAs to the neuronal cell body.
Collapse
Affiliation(s)
- R Kleiman
- Department of Neuroscience, University of Virginia Health Sciences Center, Charlottesville 22908
| | | | | |
Collapse
|
34
|
Clayson ET, Kelly SA, Meier HL. Effects of specific inhibitors of cellular functions on sulfur mustard-induced cell death. Cell Biol Toxicol 1993; 9:165-75. [PMID: 8242432 DOI: 10.1007/bf00757578] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This study was conducted to determine whether inhibitors of normal cellular functions can reduce cytotoxicity induced by sulfur mustard (HD). The compounds examined include inhibitors of poly(ADP-ribose) polymerase (PADPRP), inhibitors of mono(ADP-ribose) transferase (MADPRT), inhibitors of lipid peroxidation, and an inhibitor of protein synthesis. To determine the effects of these compounds on HD-induced cell death, human lymphocyte preparations were treated with known concentrations (0.1 microM to 1000 microM) of an inhibitor and exposed to an estimated 87% effect concentration (EC87) of HD (170 microM) for loss in cell viability. Cell viability was determined at 24-26 hr post-exposure to HD using a dye (propidium iodide) exclusion assay and a flow cytometer. All of the selected PADPRP inhibitors were found to be effective at reducing the cytotoxic effects of HD. These inhibitors were rank-ordered based on the concentration that gives 50% (EC50) reduction of HD-induced cell death. A significant correlation (r = 0.94) was observed between the compounds' ability to inhibit PADPRP and the compounds' ability to reduce HD- induced cell death, suggesting that PADPRP plays a role in HD-induced cell death. Inhibitors of MADPRT, lipid peroxidation, and protein synthesis were not effective at reducing HD-induced cell death.
Collapse
Affiliation(s)
- E T Clayson
- Basic Assessment Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010-5425
| | | | | |
Collapse
|
35
|
Motlik J, Nagai T, Kikuchi K. Resumption of meiosis in pig oocytes cultured with cumulus and parietal granulosa cells: the effect of protein synthesis inhibition. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1991; 259:386-91. [PMID: 1919466 DOI: 10.1002/jez.1402590314] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In denuded and cumulus-enclosed pig oocytes, puromycin at concentrations 5, 10, and 25 micrograms/ml did not lower the rate of germinal vesicle breakdown (GVBD) after 24 h of culture. GVBD was prevented in 50, 75, and 100 micrograms/ml of puromycin. After 40 h of culture, 5 and 10 micrograms puromycin/ml impaired significantly incidence of metaphase II (42 and 30%), respectively. Concentrations of 25 and 50 micrograms puromycin/ml absolutely prevented the first polar body (I PB) expulsion. The results indicated that GVBD in pig oocytes is far less sensitive to puromycin than I PB expulsion. Culture of cumulus-enclosed pig oocytes isolated with a piece of membrana granulosa (C + P oocytes) did not allow GVBD after 24 and 32 h in control medium. After 24 h of culture, GVBD occurred in 43 and 56% of C + P oocytes in the medium supplemented with 17 and 25 micrograms puromycin/ml. GV was broken down in 80 and 68% of C + P oocytes cultured in 17 and 25 micrograms puromycin/ml for 32 h. It is concluded that inhibition of protein synthesis by puromycin released pig oocytes from the block exerted by granulosa cells.
Collapse
Affiliation(s)
- J Motlik
- Department of Genetics, Czechoslovak Academy of Sciences, Libechov
| | | | | |
Collapse
|
36
|
Meijer AE. The pentose phosphate pathway in skeletal muscle under patho-physiological conditions. A combined histochemical and biochemical study. PROGRESS IN HISTOCHEMISTRY AND CYTOCHEMISTRY 1991; 22:1-118. [PMID: 2011653 DOI: 10.1016/s0079-6336(11)80052-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Over the last 30 years, research into the neuromuscular apparatus, has expanded greatly. Multidisciplinary investigations have rapidly advanced our understanding both of diseases and of the basic neuromuscular mechanisms. The mode of pathological reaction of the neuromuscular apparatus is now quite well understood. The most notable aspect of the reaction of the injured neuromuscular apparatus is the remarkably stereotyped character of the resulting pathological changes as demonstrated by a wide variety of harmful causes, producing surprisingly similar effects. The findings of our combined histochemical and biochemical investigations presented in this monograph, are in complete harmony with the stereotyped character of the pathological changes. For example, it is particularly striking that many affected muscle fibres of patients with muscular dystrophies, congenital myopathies, inflammatory myopathies, metabolic myopathies, endocrine myopathies, or with diseases of the lower motor neuron, display an enhanced activity of both oxidative enzymes of the pentose phosphate pathway. Likewise, we found that experimental animals with disordered skeletal muscles, provoked by different types of agents or treatments, reveal the same marked rise in activity of GPDH and PGDH in the muscle fibres, with a positive correlation between the activity of both enzymes. Other findings of our investigations point to a positive correlation between the activity of GPDH and PGDH on the one hand and that of the non-oxidative enzymes of the pentose phosphate pathway, the enzymes TA, TK, RPI and RPE on the other hand. The rise in activity of PGDH and, in particular, of GPDH is regulated by two different mechanisms. The first represents a rapid control mechanism based on the stimulation of both oxidative enzymes of the pentose phosphate pathway by NADP+ and on their inhibition by NADPH. The other mechanism represents a long-term effect directed at the synthesis of the enzymes. It is this type of mechanism which is responsible for the rise in activity of GPDH and PGDH we observed. The findings obtained with the applied enzyme histochemical techniques clearly demonstrated that the rise in activity of both enzymes is not homogeneously distributed in the disordered skeletal muscles of man and experimental animals. For that reason, in order to obtain reliable quantitative information about enzyme activities in the muscle fibres themselves, the application of biochemical assays on a micro-scale was indispensable. The biochemical assay of enzyme activities was performed on histologically and histochemically selected dissected muscle specimens.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- A E Meijer
- Department of Neurology, University of Amsterdam, The Netherlands
| |
Collapse
|
37
|
Motlík J, Rimkevicová Z. Combined effects of protein synthesis and phosphorylation inhibitors on maturation of mouse oocytes in vitro. Mol Reprod Dev 1990; 27:230-4. [PMID: 1964058 DOI: 10.1002/mrd.1080270308] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In denuded mouse oocytes, neither 3 nor 5 hours of preincubation in dbcAMP (1 mM) and cycloheximide (10 micrograms/ml), followed by further 3 hours in cycloheximide only, lowered the rate of GVBD (93% and 92%, respectively). It means that 3 and 5 hours preincubation in cycloheximide did not impair the ability of mouse oocytes to resume meiosis in medium with the protein synthesis inhibitor. To test the combined effects of inhibition of protein phosphorylation and protein synthesis, oocytes were cultured for 3, 4, or 5 hours in 2 mM of 6-DMAP and subsequently for 3 hours in 10 micrograms/ml cycloheximide. The incubation in 6-DAMP for 4 or 5 hours diminished (63% or 35% of GVBD, respectively) the ability of mouse oocytes to resume meiosis when subsequent protein synthesis was blocked by cycloheximide. However, the highly condensed bivalents were always visible in GVs. Thus the above treatment did not prevent chromatin condensation although GVBD was blocked.
Collapse
Affiliation(s)
- J Motlík
- Department of Genetics, Czechoslovak Academy of Sciences, Libĕchov
| | | |
Collapse
|
38
|
Eckert R, Hescheler J, Krautwurst D, Schultz G, Trautwein W. Calcium currents of neuroblastoma x glioma hybrid cells after cultivation with dibutyryl cyclic AMP and nickel. Pflugers Arch 1990; 417:329-35. [PMID: 2177186 DOI: 10.1007/bf00371000] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The long-term modulation of calcium (Ca2+) currents (ICa) was studied in 108CC15 neuroblastoma x glioma hybrid (NxG) cells grown under various culture conditions. The following results were obtained: 1. Addition of 1 mM dibutyryl cyclic adenosine monophosphate (db-cAMP) or 0.1 microM forskolin to the culture medium increased a transient component of ICa two-fold within 3 days, from 21.0 +/- 1.6 pA/pF (n = 22) to a maximum of 40.0 +/- 2.6 pA/pF (n = 28). Under these conditions, cells also expressed a slowly inactivating ICa component (maximum after 3 days, 20.5 +/- 1.6 pA/pF, n = 28). 2. The fast inactivating ICa as well as the db-cAMP-induced slowly inactivating ICa were completely down-regulated during incubation of NxG cells with the inorganic Ca2+ channel blocker, nickel (Ni2+, 100 microM). The suppressing effect was reversed within 3 days of incubation in db-cAMP-containing medium lacking Ni2+. 3. Binding studies on membrane preparations of control and Ni2(+)-pretreated NxG cells revealed a marked difference in the maximal (+)3H-PN200-110 binding. The difference was seen in undifferentiated as well as in db-cAMP-incubated cells. 4. The protein synthesis blocker, cycloheximide, suppressed both the db-cAMP-induced increase and the reappearance of ICa following Ni2+ pretreatment. It is suggested that chronic application of db-cAMP or Ni2+ to NxG cells increases and decreases the number of Ca2+ channel proteins, respectively.
Collapse
Affiliation(s)
- R Eckert
- II. Physiologisches Institut, Universität des Saarlandes, Homburg/Saar, Federal Republic of Germany
| | | | | | | | | |
Collapse
|
39
|
Hurwitz RL, Hirsch KM, Clark DJ, Holcombe VN, Hurwitz MY. Induction of a calcium/calmodulin-dependent phosphodiesterase during phytohemagglutinin-stimulated lymphocyte mitogenesis. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38973-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
40
|
Ferreras JM, Iglesias R, Girbés T. Effect of the chronic ethanol action on the activity of the general amino-acid permease from Saccharomyces cerevisiae var. ellipsoideus. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 979:375-7. [PMID: 2647148 DOI: 10.1016/0005-2736(89)90260-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The presence of ethanol and cycloheximide during growth were found to inhibit the function of the general amino-acid permease of Saccharomyces cerevisiae var. ellipsoideus. Contrary to cycloheximide, the effect of ethanol upon growth in alcohol-free medium was reversible. The effect of both inhibitors could be explained in terms of reduction of the number of active carrier molecules located in the plasma membrane.
Collapse
Affiliation(s)
- J M Ferreras
- Departamento de Bioquímica, Biología Molecular y Fisiología, Facultad de Ciencias, Universidad de Valladolid, Spain
| | | | | |
Collapse
|
41
|
Donohue TM, Zetterman RK, Tuma DJ. Effect of chronic ethanol administration on protein catabolism in rat liver. Alcohol Clin Exp Res 1989; 13:49-57. [PMID: 2646978 DOI: 10.1111/j.1530-0277.1989.tb00283.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hepatic protein catabolism was measured in rats which were pair-fed a liquid diet containing either ethanol or isocaloric maltose-dextrin (control diet). Within 12 days after initiation of pair feeding, the level of total hepatic protein in ethanol-fed rats was 26% higher than that in pair-fed control rats. During this time interval, the catabolic rates of both short-lived [3H]puromycin-labeled proteins and long-lived native [14C]bicarbonate-labeled proteins were measured in the two groups of animals. The degradation rate of short-lived [3H]puromycinyl proteins and peptides was the same in ethanol-fed and pair-fed control rats. However, the overall catabolic rate of long-lived proteins in rats fed the ethanol liquid diet for 2-10 days was 37-40% lower than that in pair-fed controls. This difference in protein turnover was not a general phenomenon, since the time-dependent decay of [14C]proteins in the hepatic microsome fraction of ethanol-fed rats was 33% slower than that in pair-fed controls, but the apparent rate of cytosolic protein catabolism was the same in both groups of animals. The differences in protein turnover did not reflect quantitative changes in lysosomal proteases since the activities of four hepatic lysosomal cathepsins were unaffected by alcohol administration. When rats were subjected to longer periods of pair feeding (16-25 days), the difference in overall hepatic protein catabolism between ethanol-fed rats and their pair-fed controls was considerably attenuated.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- T M Donohue
- Liver Study Unit, Veterans Administration Medical Center, Omaha, NE 68105
| | | | | |
Collapse
|
42
|
Lázaro E, van den Broek LA, Ottenheijm HC, Lelieveld P, Ballesta JP. Structure-activity relationships of sparsomycin: modification at the hydroxyl group. Biochimie 1987; 69:849-56. [PMID: 3122847 DOI: 10.1016/0300-9084(87)90211-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Ten analogues of the antibiotic sparsomycin were prepared and evaluated in several in vitro tests. Nine of them carry a modification at the hydroxymethylene group of the molecule, two have a disulfide bond instead of the S(O)-CH2-S moiety at the sulfur-containing side chain of the molecule. While the presence of the S-S group decreases the activity of the analogues in all the tests performed, the modification at the OH group has no deleterious effects on the activity when a polyphenylalanine synthesis assay is used in an Escherichia coli extract. The same modifications, however, diminish drastically the activity of the analogues when tested in a similar Saccharomyces cerevisiae extract. A polymerization system in the archaebacterium Halobacterium halobium extract behaves like the eukaryotic preparations. A discrepancy is also found between the results of the polymerization tests and those of the 'puromycin reaction' which is also less sensitive to the modified sparsomycin analogues. The results of cell growth inhibition tests in bacteria as well as in eukaryotic organisms agree only partially with the in vitro data.
Collapse
Affiliation(s)
- E Lázaro
- Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Madrid, Spain
| | | | | | | | | |
Collapse
|
43
|
Denis H, le Maire M. Biochemical research on oogenesis: protein synthesis in whole cells and in cell-free extracts of Xenopus laevis immature ovaries. Biochimie 1987; 69:475-83. [PMID: 3118963 DOI: 10.1016/0300-9084(87)90085-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nearly all tRNA molecules in previtellogenic oocytes of Xenopus laevis are included in nucleoprotein particles sedimenting at 42S. The tRNA-binding sites of these particles have several properties in common with those of the ribosomes. This suggests that the 42S particles might behave like unprogrammed ribosomes and be the site of a template-independent polymerization of amino acids. We expected this reaction to be insensitive to protein synthesis inhibitors, such as cycloheximide and puromycin. We found that these antibiotics almost completely inhibit the incorporation of labeled amino acids into protein, when added to the incubation medium of whole ovaries or free oocytes. In cell-free extracts of ovaries, the incorporation of amino acids is partially insensitive to cycloheximide and puromycin. When such extracts are fractionated by sucrose density centrifugation and incubated with ATP, a major peak of amino acid incorporation can be detected, which nearly coincides with the 42S particle peak.
Collapse
Affiliation(s)
- H Denis
- Laboratoire de Biochimie du Développement, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | | |
Collapse
|
44
|
le Maire M, Denis H. Biochemical research on oogenesis: protein synthesis by purified 42S particles from Xenopus laevis and Tinca tinca previtellogenic oocytes. Biochimie 1987; 69:485-93. [PMID: 3118964 DOI: 10.1016/0300-9084(87)90086-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
When incubated with ATP and a labeled amino acid, the 42S particles from early oocytes of Xenopus laevis and Tinca tinca incorporate radioactivity into tRNA and into a high molecular mass material which can be identified as protein. This incorporation is totally independent of ribosomes of cytosolic, mitochondrial or bacterial origin. The incorporated amino acids are linked to a broad spectrum of proteins by covalent bonds. Simple treatments such as incubation in buffer or addition of synthetic polyribonucleotides can inhibit the protein-labeling activity of the particles without affecting their tRNA aminoacylation activity. The former activity corresponds either to an amino acid polymerization reaction or to a protein-modifying reaction of a novel type. No involvement of mRNA in this process has been demonstrated. The alleged amino acid polymerization activity of the 42S particles could be a consequence of the conditions provided to aminoacyl tRNA by the tRNA-binding sites of the particles. These conditions are likely to allow the peptidyl transfer reaction to take place, although at a much lower rate than in the ribosome.
Collapse
Affiliation(s)
- M le Maire
- Laboratoire de Biochimie du Développement, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | | |
Collapse
|
45
|
Cheney B, Miller AB. Structural comparisons of antibiotic inhibitors of peptidyl transferase. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0166-1280(86)80010-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
46
|
Chládek S, Sprinzl M. Das 3′-Ende der tRNA und seine Rolle bei der Proteinbiosynthese. Angew Chem Int Ed Engl 1985. [DOI: 10.1002/ange.19850970506] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
47
|
Ganoza MC, Zahid N, Baxter RM. Stimulation of peptidyltransferase reactions by a soluble protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 146:287-94. [PMID: 3881259 DOI: 10.1111/j.1432-1033.1985.tb08651.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The requirements for peptide-bond synthesis and transesterification reactions of Escherichia coli 70S ribosomes, 50S native or reconstructed 50S subunits were examined using fMet-tRNA as donor substrate and puromycin or alpha-hydroxypuromycin as acceptors. We report that the soluble protein EF-P, purified to apparent homogeneity, stimulates the synthesis of N-formylmethionylpuromycin or N-formylmethionylhydroxypuromycin by 70S ribosomes or reassociated 30S and 50S subunits. In the presence of EF-P, 70S ribosomes are significantly more efficient than 50S particles in catalysing either peptide-bond synthesis or transesterification. The involvement of 50S subunit proteins in EF-P-stimulated peptide-bond formation and transesterification was studied. 50S subunits were dissociated by 2.0 M LiCl into core particles and 'split' proteins, several of which were purified to homogeneity. When added to 30S X A-U-G X f[35S]Met-tRNA, 50S cores or 50S cores reconstituted with L6 or L11 promoted peptide-bond synthesis or transesterification poorly. EF-P stimulated peptide-bond synthesis by both these types of core particles to approximately the same extent. On the other hand, EF-P stimulated a low level of transesterification by cores reconstituted with L6 and L11. In contrast, core particles reconstituted with L16 exhibited both peptide-bond-forming and transesterification activities and EF-P stimulated both reactions twentyfold and fortyfold respectively. Thus different proteins differentially stimulate the intrinsic or EF-P-stimulated peptide-bond and transesterification reactions of the peptidyl transferase. Ethoxyformylation of either 50S subunits or purified L16 used to reconstitute core particles, resulted in loss of peptide-bond formation and transesterification. Similarly ethoxyformylation of EF-P resulted in a 25-50% loss of its ability to stimulate both reactions. 30S subunits were resistant to treatment by this reagent. These results suggest the involvement of histidine residues in peptidyltransferase activities. The role of EF-P in the catalytic mechanism of peptidyltransferase is discussed.
Collapse
|
48
|
Yayon A, Friedman S, Ginsburg H. Plasmodium falciparum: elimination of fungal and bacterial contamination from in vitro culture. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1984; 78:167-8. [PMID: 6378111 DOI: 10.1080/00034983.1984.11811791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
49
|
Moureau P, Engelborghs Y, Di Giambattista M, Cocito C. Fluorescence stopped flow analysis of the interaction of virginiamycin components and erythromycin with bacterial ribosomes. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43849-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
50
|
Kukhanova M, Victorova L, Krayevsky A. Peptidyltransferase center of ribosomes. On the mechanism of action of alkaloid lycorine. FEBS Lett 1983; 160:129-33. [PMID: 6350039 DOI: 10.1016/0014-5793(83)80951-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The molecular mechanism of action of the alkaloid lycorine has been revised. According to our results, lycorine inhibits the binding of CACCA-Leu comes from Ac to the donor site of the peptidyltransferase center of wheat-germ ribosomes, whereas the transpeptidation reaction in the system with the minimal model donor is not inhibited. The equilibrium constant of CACCA-Leu comes from Ac to the donor site of 80 S ribosomes is measured.
Collapse
|