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Korem Kohanim Y, Levi D, Jona G, Towbin BD, Bren A, Alon U. A Bacterial Growth Law out of Steady State. Cell Rep 2019; 23:2891-2900. [PMID: 29874577 DOI: 10.1016/j.celrep.2018.05.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 02/21/2018] [Accepted: 05/01/2018] [Indexed: 11/28/2022] Open
Abstract
Bacterial growth follows simple laws in constant conditions. However, bacteria in nature often face fluctuating environments. We therefore ask whether there are growth laws that apply to changing environments. We derive a law for upshifts using an optimal resource-allocation model: the post-shift growth rate equals the geometrical mean of the pre-shift growth rate and the growth rate on saturating carbon. We test this using chemostat and batch culture experiments, as well as previous data from several species. The increase in growth rate after an upshift indicates that ribosomes have spare capacity (SC). We demonstrate theoretically that SC has the cost of slow steady-state growth but is beneficial after an upshift because it prevents large overshoots in intracellular metabolites and allows rapid response to change. We also provide predictions for downshifts. The present study quantifies the optimal degree of SC, which rises the slower the growth rate, and suggests that SC can be precisely regulated.
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Affiliation(s)
- Yael Korem Kohanim
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dikla Levi
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ghil Jona
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Benjamin D Towbin
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Anat Bren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Kim YD, Lee J, Kim HS, Lee MO, Son MY, Yoo CH, Choi JK, Lee SC, Cho YS. The unique spliceosome signature of human pluripotent stem cells is mediated by SNRPA1, SNRPD1, and PNN. Stem Cell Res 2017; 22:43-53. [PMID: 28595116 DOI: 10.1016/j.scr.2017.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Spliceosomes are the core host of pre-mRNA splicing, allowing multiple protein isoforms to be produced from a single gene. Herein, we reveal that spliceosomes are more abundant in human pluripotent stem cells (hPSs), including human embryonic stem cells (hESs) and human induced pluripotent stem cells (hiPSs), than non-hPSs, and their presence is associated with high transcriptional activity. Supportively, spliceosomal components involved in the catalytically active pre-mRNA splicing step were mainly co-localized with hPS spliceosomes. By profiling the gene expression of 342 selected splicing factors, we found that 71 genes were significantly altered during the reprogramming of human somatic cells into hiPSs. Among them, SNRPA1, SNRPD1, and PNN were significantly up-regulated during the early stage of reprogramming, identified as hub genes by interaction network and cluster analysis. SNRPA1, SNRPD1, or PNN depletion led to a pronounced loss of pluripotency and significantly blocked hiPS generation. SNRPA1, SNRPD1, and PNN co-localized with the hPS spliceosomes, physically interacted with each other, and positively influenced the appearance of hPS spliceosomes. Our data suggest that SNRPA1, SNRPD1, and PNN are key players in the regulation of pluripotency-specific spliceosome assembly and the acquisition and maintenance of pluripotency.
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Affiliation(s)
- Young-Dae Kim
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Jungwoon Lee
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Han-Seop Kim
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Mi-Ok Lee
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Mi-Young Son
- Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Chae Hwa Yoo
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Jung-Kyun Choi
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea; Department of Bioscience, KRIBB School, University of Science & Technology, 113 Gwahak-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Sang Chul Lee
- Research Center for Metabolic Regulation, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Yee Sook Cho
- Stem Cell Research Laboratory, Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, Republic of Korea; Department of Bioscience, KRIBB School, University of Science & Technology, 113 Gwahak-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
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Ehrenberg M, Bremer H, Dennis PP. Medium-dependent control of the bacterial growth rate. Biochimie 2012; 95:643-58. [PMID: 23228516 DOI: 10.1016/j.biochi.2012.11.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/22/2012] [Indexed: 11/26/2022]
Abstract
By combining results from previous studies of nutritional up-shifts we here re-investigate how bacteria adapt to different nutritional environments by adjusting their macromolecular composition for optimal growth. We demonstrate that, in contrast to a commonly held view the macromolecular composition of bacteria does not depend on the growth rate as an independent variable, but on three factors: (i) the genetic background (i.e. the strain used), (ii) the physiological history of the bacteria used for inoculation of a given growth medium, and (iii) the kind of nutrients in the growth medium. These factors determine the ribosome concentration and the average rate of protein synthesis per ribosome, and thus the growth rate. Immediately after a nutritional up-shift, the average number of ribosomes in the bacterial population increases exponentially with time at a rate which eventually is attained as the final post-shift growth rate of all cell components. After a nutritional up-shift from one minimal medium to another minimal medium of higher nutritional quality, ribosome and RNA polymerase syntheses are co-regulated and immediately increase by the same factor equal to the increase in the final growth rate. However, after an up-shift from a minimal medium to a medium containing all 20 amino acids, RNA polymerase and ribosome syntheses are no longer coregulated; a smaller rate of synthesis of RNA polymerase is compensated by a gradual increase in the fraction of free RNA polymerase, possibly due to a gradual saturation of mRNA promoters. We have also analyzed data from a recent publication, in which it was concluded that the macromolecular composition in terms of RNA/protein and RNA/DNA ratios is solely determined by the effector molecule ppGpp. Our analysis indicates that this is true only in special cases and that, in general, medium adaptation also depends on factors other than ppGpp.
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Affiliation(s)
- Måns Ehrenberg
- Department of Cell and Molecular Biology, BMC, Uppsala University, Box 596, S-751 24 Uppsala, Sweden.
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Boddicker JD, Jones BD. Lon protease activity causes down-regulation of Salmonella pathogenicity island 1 invasion gene expression after infection of epithelial cells. Infect Immun 2004; 72:2002-13. [PMID: 15039320 PMCID: PMC375200 DOI: 10.1128/iai.72.4.2002-2013.2004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Salmonella enterica serovar Typhimurium causes self-limiting gastroenteritis in humans and a typhoid-like disease in mice that serves as a model for typhoid infections in humans. A critical step in Salmonella pathogenesis is the invasion of enterocytes and M cells of the small intestine via expression of a type III secretion system, encoded on Salmonella pathogenicity island 1 (SPI-1), that secretes effector proteins into host cells, leading to engulfment of the bacteria within large membrane ruffles. The in vitro regulation of invasion genes has been the subject of much scientific investigation. Transcription of the hilA gene, which encodes an OmpR/ToxR-type transcriptional activator of downstream invasion genes, is increased during growth under high-osmolarity and low-oxygen conditions, which presumably mimic the environment found within the small intestine. Several negative regulators of invasion gene expression have been identified, including HilE, Hha, and Lon protease. Mutations within the respective genes increase the expression of hilA when the bacteria are grown under environmental conditions that are not favorable for hilA expression and invasion. In this study, the intracellular expression of invasion genes was examined, after bacterial invasion of HEp-2 epithelial cells, using Salmonella strains containing plasmid-encoded short-half-life green fluorescent protein reporters of hilA, hilD, hilC, or sicA expression. Interestingly, the expression of SPI-1 genes was down-regulated after invasion, and this was important for the intracellular survival of the bacteria. In addition, the effects of mutations in genes encoding negative regulators of invasion on intracellular hilA expression were examined. Our results indicate that Lon protease is important for down-regulation of hilA expression and intracellular survival after the invasion of epithelial cells.
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Affiliation(s)
- Jennifer D Boddicker
- Department of Microbiology, Roy J. and Lucille A. Carver School of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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5
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Lindahl L, Zengel JM. Autogenous control is not sufficient to ensure steady-state growth rate-dependent regulation of the S10 ribosomal protein operon of Escherichia coli. J Bacteriol 1990; 172:305-9. [PMID: 2152906 PMCID: PMC208433 DOI: 10.1128/jb.172.1.305-309.1990] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The regulation of the S10 ribosomal protein operon of Escherichia coli was studied by using a lambda prophage containing the beginning of the S10 operon (including the promoter, leader, and first one and one-half structural genes) fused to lacZ. The synthesis of the lacZ fusion protein encoded by the phage showed the expected inhibition during oversynthesis of ribosomal protein L4, the autogenous regulatory protein of the S10 operon. Moreover, the fusion gene responded to a nutritional shift-up in the same way that genuine ribosomal protein genes did. However, the gene did not exhibit the expected growth rate-dependent regulation during steady-state growth. Thus, the genetic information carried on the prophage is sufficient for L4-mediated autogenous control and a normal nutritional shift-up response but is not sufficient for steady-state growth rate-dependent control. These results suggest that, at least for the 11-gene S10 ribosomal protein operon, additional regulatory processes are required to coordinate the synthesis of ribosomal proteins with cell growth rate and, furthermore, that sequences downstream of the proximal one and one-half genes of the operon are involved in this control.
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Affiliation(s)
- L Lindahl
- Department of Biology, University of Rochester, New York 14627
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6
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Wikström PM, Byström AS, Björk GR. Non-autogenous control of ribosomal protein synthesis from the trmD operon in Escherichia coli. J Mol Biol 1988; 203:141-52. [PMID: 2460631 DOI: 10.1016/0022-2836(88)90098-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The trmD operon of Escherichia coli encodes the ribosomal proteins S16 and L19, the tRNA(m1G37)methyltransferase and a 21,000 Mr protein of unknown function. Here we demonstrate that, in contrast to the expression of other ribosomal protein operons, the amount of trmD operon mRNA and the rate of synthesis of the proteins encoded by the operon respond to increased gene dosage. The steady-state level of the mRNA was about 18 times higher, and the relative rate of synthesis of the ribosomal proteins S16 and L19, the tRNA(m1G37)methyltransferase and the 21,000 Mr protein was 15, 9, 25 and 23 times higher, respectively, in plasmid-containing cells than in plasmid-free cells. Overproduced tRNA(m1G37)methyltransferase and 21,000 Mr protein were as stable as E. coli total protein, whereas the two ribosomal proteins were degraded to a large extent. The steady-state amount of S16 and L19 in the plasmid-containing cells exceeded that in plasmid-free cells by threefold and twofold, respectively. No significant effect on the synthesis of the trmD operon proteins from the chromosomally located genes was observed when parts of the operon were expressed on different plasmids. Taken together, these results suggest that the expression of the trmD operon is not subject to transcriptional or translational feedback regulation, and demonstrate that not all ribosomal protein operons are regulated in the same manner. We propose that ribosomal protein operons that do not encode proteins that bind directly to rRNA are not under autogenous control. Metabolic regulation at the transcriptional level and protein degradation are plausible mechanisms for the control of expression of such operons.
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Affiliation(s)
- P M Wikström
- Department of Microbiology, University of Umeå, Sweden
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7
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Zengel JM, Lindahl L. Transcription of ribosomal genes during a nutritional shift-up of Escherichia coli. J Bacteriol 1986; 167:1095-7. [PMID: 2427499 PMCID: PMC215991 DOI: 10.1128/jb.167.3.1095-1097.1986] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We measured the differential transcription rates of individual ribosomal operons after a nutritional shift-up. All operons showed a transient increase in transcription. However, the response of the S10 ribosomal protein operon was much stronger than that of any other operon. We propose that only the S10 operon is autogenously regulated by a transcription attenuation mechanism.
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9
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Dowsett SJ, Sells BH. Synthesis of ribosomal proteins in merodiploid strains of Escherichia coli. MOLECULAR & GENERAL GENETICS : MGG 1980; 180:331-41. [PMID: 6450871 DOI: 10.1007/bf00425845] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The regulation of the synthesis of r-proteins in Escherichia coli was investigated by increasing the dosage of the genes for a limited number of ribosomal proteins (r-proteins) using either transducing phage lambda fus 3 (Lindahl et al. 1977) or lambda rifd 18 (Kirschbaum and Konrad 1973). During exponential growth the presence in the cell of either lysogenised transducing phage did not increase the rate of synthesis or degradation of any of the 31 r-proteins whose genes are duplicated. Experiments were also performed to determine whether r-protein synthesis during the period of unbalanced r-protein synthesis that follows nutritional enrichment was sensitive to an increase in gene dosage. Duplication of the 27 r-protein genes on lambda fus 3 did not alter the rate of synthesis of any of the r-proteins after enrichment. However, gene dosage effects were detected for at least 3 of the r-proteins whose genes were duplicated on lambda rifd 18.
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Shepherd N, Churchward G, Bremer H. Synthesis and function of ribonucleic acid polymerase and ribosomes in Escherichia coli B/r after a nutritional shift-up. J Bacteriol 1980; 143:1332-44. [PMID: 6157673 PMCID: PMC294508 DOI: 10.1128/jb.143.3.1332-1344.1980] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The syntheses of stable ribosomal ribonucleic acid (RNA) and transfer RNA in bacteria depend on the concentration and activity of RNA polymerase and on the fraction of active RNA polymerase synthesizing stable RNA. These parameters were measured in Escherichia coli B/r after a nutritional shift-up from succinate-minimal to glucose-amino acids medium and were found to change in complex patterns during a 1- to 2-h period after the shift-up before reaching a final steady-state level characteristic for the postshift growth medium. The combined effect of these changes was an immediate, one-step increase in the exponential rate of stable RNA synthesis and thus of ribosome synthesis. This suggests that the distribution of transcribing RNA polymerase over ribosomal and nonribosomal genes and the polymerase activity are continuously adjusted during postshift growth to some growth-limiting reaction whose rate increases exponentially. It is proposed that this reaction is the production of amino-acylated transfer RNA and that is exponentially increasing rate results in part from a gradually increasing concentration of aminoacyl transfer RNA synthetases after a shift-up. This idea was tested and is supported by a computer simulation of a nutritional shift-up.
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Isono K, Isono S. Ribosomal protein modification in Escherichia coli. II. Studies of a mutant lacking the N-terminal acetylation of protein S18. MOLECULAR & GENERAL GENETICS : MGG 1980; 177:645-51. [PMID: 6991870 DOI: 10.1007/bf00272675] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A mutant of Escherichia coli K12 has been isolated which shows an alteration in the ribosomal protein S18. Genetic analyses have revealed that the mutation causing this alteration maps at 99.3 min of the E. coli genetic map, between dnaC and deo. This indicated that the mutation has occurred in a gene different from the structural gene for this protein which has been located at 94 min. From the N-terminal amino acid sequence analysis it is concluded that the mutation has resulted in loss of the N-terminal acetyl group of this protein. The gene which is affected in this mutant is termed rimI that most likely specifies an enzyme acetylating the N-terminal alanine of protein S18. The mutation does not affect the acetylation of two other ribosomal proteins, S5 and L12, both of which are known to be acetylated in wild-type E. coli K12.
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12
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Adachi K, Boyle S, Sells B. Synthesis of ribosomal protein S1 following nutritional shift-up in Escherichia coli K-12. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)86178-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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13
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Gorenstein C, Warner JR. The monocistronic nature of ribosomal protein genes in yeast. Curr Genet 1979; 1:9-12. [DOI: 10.1007/bf00413302] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/1979] [Indexed: 11/29/2022]
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Fallon AM, Jinks CS, Yamamoto M, Nomura M. Expression of ribosomal protein genes cloned in a hybrid plasmid in Escherichia coli: gene dosage effects on synthesis of ribosomal proteins and ribosomal protein messenger ribonucleic acid. J Bacteriol 1979; 138:383-96. [PMID: 374386 PMCID: PMC218189 DOI: 10.1128/jb.138.2.383-396.1979] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Using ColE1-TnA hybrid plasmid RSF2124 as the cloning vector, we constructed a hybrid plasmid, pNO1001, which carried seven ribosomal protein (r-protein) genes in the spc operon together with their promoter. The plasmid also carried three r-protein genes which precede the spc operon, but did not carry the bacterial promoter for these genes. Expression of r-protein genes carried by pNO1001 was studied by measuring messenger ribonucleic acid and r-protein synthesis in cells carrying the plasmid. It was found that the messenger ribonucleic acid for all the promoter-distal r-protein genes was synthesized in large excess relative to messenger ribonucleic acid from other chromosomal r-protein genes which are not carried by the plasmid. However, only the two promoter-proximal r-proteins, L14 and L24, were markedly overproduced. The absence of large gene dosage effects on the synthesis of other distal proteins appeared to be due, at least in part, to preferential inactivation and/or degradation of the distal message which codes for these proteins; in addition, some preferential inhibition of translation of the distal message might also have been involved. Overproduced L14 and L24 were found to be degraded in recA+ strains at both 30 and 42 degrees C; in recA strains, the degradation took place at 42 degrees C but was very slow or absent at 30 degrees C. The recA strains carrying pNO1001 failed to form colonies at 30 degrees C, presumably because of overaccumulation of r-proteins. The results suggest that degradation of excess r-proteins is an important physiological process.
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Enzyme production during transient growth. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1979. [DOI: 10.1007/3540092625_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Lindahl L, Post L, Zengel J, Gilbert SF, Strycharz WA, Nomura M. Mapping of ribosomal protein genes by in vitro protein synthesis using DNA fragments of lambdafus3 transducing phage DNA as templates. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(19)66975-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Molin S, Von Meyenburg K, Maaloe O, Hansen MT, Pato ML. Control of ribosome synthesis in Escherichia coli: analysis of an energy source shift-down. J Bacteriol 1977; 131:7-17. [PMID: 326772 PMCID: PMC235384 DOI: 10.1128/jb.131.1.7-17.1977] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The rate of ribosome synthesis and accumulation in Escherichia coli during the transition after an energy source shift-down was analyzed. The shift was imposed on cultures of stringent and relaxed strains growing in glucose minimal medium by the addition of the glucose analogue alpha-methylglucoside. In the stringent strain, ribosome synthesis was almost instantaneously reduced after the shift, whereas the relaxed strain exhibited a more gradual response. The rate of messenger ribonucleic acid (mRNA) synthesis was affected similarly, though to a smaller extent. A comparison of the rates of synthesis and accumulation of ribosomal RNA (rRNA) and ribosomal proteins showed that far more ribosomal components were synthesized after the shift than were accumulated, indicating that a substantial part of the rRNA made after the shift was unstable. A new method was used to measure relative rates of rRNA synthesis and to estimate the transcription time for the rRNA operon under different conditions. In steady states of growth with growth rates ranging from 0.75 to 2.3 doublings/h, as well as during the transition after a shift-down, the transcription time of the rRNA operon was constant. The rate of synthesis of rRNA correlated during this transition - in contrast to the rate of accumulation (M. T. Hansen et al., J. Bacteriol. 122: 585-591, 1975) - with the ppGpp pool in the same way as has been observed during partial amino acid starvation.
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Champney WS. Kinetics of ribosome synthesis during a nutritional shift-up in Escherischia coli K-12. MOLECULAR & GENERAL GENETICS : MGG 1977; 152:259-66. [PMID: 327281 DOI: 10.1007/bf00693079] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The rates of total protein synthesis, polyribosome formation and 70S ribosome accumulation were measured following a nutritional shift-up of Escherichia coli K-12. Changes in ribosome content and distribution during the shift-up were measured by examining the total cellular content of free and polysome-associated ribosomes using a sensitive double isotope labeling method. The kinetics of ribosomal subunit formation and the biosynthesis of subunit protein and RNA species were also defined. The results indicated that a pre-shift population of ribosomal subunits was utilized for the immediate post shift increase in both total and ribosomal-specific protein synthesis. An assembly time for new subunits of about 3 min was observed. The formation of certain ribosomal proteins during the shift suggested that new subunit assembly was limited by the rate of synthesis of particular ribosomal proteins during this growth transition.
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Marvaldi J, Pichon J, Coeroli C, Marchis-Mouren G. On the control of ribosomal protein biosynthesis in Escherichia coli. II. Studies during recovery from amino acid starvation. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 475:228-40. [PMID: 321027 DOI: 10.1016/0005-2787(77)90014-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The rate of synthesis of ribosomal proteins relative to that of total protein was measured at various times during recovery from arginine starvation in isogenic re+ and rel- strains of Escherichia coli K 12. Total ribosomal proteins are preferentially synthesized early during recovery. Higher rates of synthesis are obtained in the rel+ strain than in the rel- strain. Differential rates of synthesis of individual ribosomal proteins are observed at the various times studied. The rate of synthesis of individual proteins increases with time up to maximum values then the rates come down to values similar to those found in exponentially growing cells. The time of restart of synthesis of each protein has been estimated (1) by the time at which the maximum value is reached, and (2) by measuring the rate of synthesis at early time (3 min). Most ribosomal proteins behave similarlly in rel- and rel+ strains. Proteins have been listed from highly labelled (early proteins) to poorly labelled (late proteins). The significance of the order of restart is considered.
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21
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Pichon JL, Coeroli C, Marchis-Mouren G. Studies on ribosomal protein biosynthesis in an RNA polymerase temperature sensitive E. coli mutant. MOLECULAR & GENERAL GENETICS : MGG 1977; 150:257-64. [PMID: 321934 DOI: 10.1007/bf00268124] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In E. coli strain XH56 the synthesis of all RNA species is blocked upon shifting the culture to the non-permissive temperature. The decay of specific messenger RNA species coding for individual ribosomal (r) proteins was followed by measuring the rate of r-protein synthesis by pulse labelling at various times after the shift. The half-lives of the average 30S r-protein and 50S r-protein mRNA species are identical (1.75 min) and shorter than those of the average messenger coding for total cell proteins (2.75 min). Most individual r-protein messengers have a half-life in the same range (1.50-2.00). Only a few r-protein messengers have significantly longer half-lives: S1 (2.80 min), S17 (3.29 min), L29 (2.30 min), L31 (2.30 min), L32 (2.33 min) and L16 (2.60 min). The results indicate that the degradation of most individual r-protein mRNA species is not specifically controlled. After a few min at the non-permissive temperature, all protein synthesis is blocked. The restart of r-protein synthesis was followed after shifting the culture back to the permissive temperature. The recovery of cell growth is very slow. During this period preferential r-protein synthesis was observed. Moreover differential rates of bisynthesis of r-proteins was obtained, it may be indicative of specific regulatory process(es).
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22
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Seals AA, Champney WS, Kushner SR. Transcription of ribosomal protein genes carried on F' plasmids of Escherichia coli. MOLECULAR & GENERAL GENETICS : MGG 1977; 150:183-91. [PMID: 320454 DOI: 10.1007/bf00695398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The transcriptional activity of the DNA sequences coding for certain ribosomal proteins has been measured in Escherichia coli. Two partial diploid strains were isolated from mating of a recA, argD, aroE recipient and an Hfr with an origin at 69.5 min. One contained an F' element carrying the genes from 69.5 to 72.7 min including the rpsL locus (72.4) and the second was diploid for the genes from 69.5 to 71.5 min but did not include any mapped ribosomal protein loci. The molecular weights of the plasmids were estimated to be 140 and 110 x 10(6) daltons, respectively. The extent of in vivo transcription of the chromosomal genes on the plasmid and the ribosomal protein mRNA fraction of the total cellular RNA weer calculated from DNA-RNA liquid hybridization experiments using both DNA and RNA excess procedures. The results indicated a high degree of transcriptional activity concentrated in the ribosomal protein sequences with 83% of the F' chromosomal sequences transcribed into mRNA products representing about 0.12% of the total cellular RNA.
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Andrésson OS, Magnúsdóttir RA, Eggertsson G. Deletions of ribosomal protein genes in Escherichia coli merodiploids heterozygous for resistance to streptomycin and spectinomycin. MOLECULAR & GENERAL GENETICS : MGG 1976; 144:127-30. [PMID: 131908 DOI: 10.1007/bf02428100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In a merodiploid strain of Escherichia coli heterozygous for the ribosomal protein genes spc and str, deletions were observed preventing the expression of either gene but permitting the expression of the other. This suggests that the spc and str genes are in separate transcriptional units.
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