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Shea J, Davis L, Quaye B, Gedeon T. Ribosome Abundance Control in Prokaryotes. Bull Math Biol 2023; 85:119. [PMID: 37861893 DOI: 10.1007/s11538-023-01212-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/06/2023] [Indexed: 10/21/2023]
Abstract
Cell growth is an essential phenotype of any unicellular organism and it crucially depends on precise control of protein synthesis. We construct a model of the feedback mechanisms that regulate abundance of ribosomes in E. coli, a prototypical prokaryotic organism. Since ribosomes are needed to produce more ribosomes, the model includes a positive feedback loop central to the control of cell growth. Our analysis of the model shows that there can be only two coexisting equilibrium states across all 23 parameters. This precludes the existence of hysteresis, suggesting that the ribosome abundance changes continuously with parameters. These states are related by a transcritical bifurcation, and we provide an analytic formula for parameters that admit either state.
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Affiliation(s)
- Jacob Shea
- Department of Mathematical Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - Lisa Davis
- Department of Mathematical Sciences, Montana State University, Bozeman, MT, 59717, USA
| | - Bright Quaye
- Department of Economics, Washington University, St. Louis, MO, USA
| | - Tomas Gedeon
- Department of Mathematical Sciences, Montana State University, Bozeman, MT, 59717, USA.
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2
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Hanafin PO, Abdul Rahim N, Sharma R, Cess CG, Finley SD, Bergen PJ, Velkov T, Li J, Rao GG. Proof-of-concept for incorporating mechanistic insights from multi-omics analyses of polymyxin B in combination with chloramphenicol against Klebsiella pneumoniae. CPT Pharmacometrics Syst Pharmacol 2023; 12:387-400. [PMID: 36661181 PMCID: PMC10014067 DOI: 10.1002/psp4.12923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/21/2022] [Accepted: 12/30/2022] [Indexed: 01/21/2023] Open
Abstract
Carbapenemase-resistant Klebsiella pneumoniae (KP) resistant to multiple antibiotic classes necessitates optimized combination therapy. Our objective is to build a workflow leveraging omics and bacterial count data to identify antibiotic mechanisms that can be used to design and optimize combination regimens. For pharmacodynamic (PD) analysis, previously published static time-kill studies (J Antimicrob Chemother 70, 2015, 2589) were used with polymyxin B (PMB) and chloramphenicol (CHL) mono and combination therapy against three KP clinical isolates over 24 h. A mechanism-based model (MBM) was developed using time-kill data in S-ADAPT describing PMB-CHL PD activity against each isolate. Previously published results of PMB (1 mg/L continuous infusion) and CHL (Cmax : 8 mg/L; bolus q6h) mono and combination regimens were evaluated using an in vitro one-compartment dynamic infection model against a KP clinical isolate (108 CFU/ml inoculum) over 24 h to obtain bacterial samples for multi-omics analyses. The differentially expressed genes and metabolites in these bacterial samples served as input to develop a partial least squares regression (PLSR) in R that links PD responses with the multi-omics responses via a multi-omics pathway analysis. PMB efficacy was increased when combined with CHL, and the MBM described the observed PD well for all strains. The PLSR consisted of 29 omics inputs and predicted MBM PD response (R2 = 0.946). Our analysis found that CHL downregulated metabolites and genes pertinent to lipid A, hence limiting the emergence of PMB resistance. Our workflow linked insights from analysis of multi-omics data with MBM to identify biological mechanisms explaining observed PD activity in combination therapy.
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Affiliation(s)
- Patrick O Hanafin
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | - Rajnikant Sharma
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Colin G Cess
- Department of Biomedical Engineering Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Stacey D Finley
- Department of Biomedical Engineering Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Phillip J Bergen
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jian Li
- Department of Microbiology, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences and Biomedicine Discovery Institute, Monash University, Parkville, Victoria, Australia
| | - Gauri G Rao
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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3
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tRNAs Are Stable After All: Pitfalls in Quantification of tRNA from Starved Escherichia coli Cultures Exposed by Validation of RNA Purification Methods. mBio 2023; 14:e0280522. [PMID: 36598190 PMCID: PMC9973347 DOI: 10.1128/mbio.02805-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
tRNAs and ribosomal RNAs are often considered stable RNAs. In contrast to this view, we recently proposed that tRNAs are degraded during amino acid starvation and drug-induced transcription inhibition. However, reevaluation of our experimental approach revealed that common RNA extraction methods suffer from alarming extraction and size biases that can lead to gross underestimation of RNA levels in starved Escherichia coli populations. Quantification of tRNAs suffers additional biases due to differing fractions of tRNAs with base modifications in growing versus starved bacteria. Applying an improved methodology, we measured tRNA levels after starvation for amino acids, glucose, phosphate, or ammonium and transcription inhibition by rifampicin. We report that tRNA levels remain largely unaffected in all tested conditions, including several days of starvation. This confirms that tRNAs are remarkably stable RNAs and serves as a cautionary tale about quantification of RNA from cells cultured outside the steady-state growth regime. rRNA, conversely, is extensively degraded during starvation. Thus, E. coli downregulates the translation machinery in response to starvation by reducing the ribosome pool through rRNA degradation, while a high concentration of tRNAs available to supply amino acids to the remaining ribosomes is maintained. IMPORTANCE We show that E. coli tRNAs are remarkably stable during several days of nutrient starvation, although rRNA is degraded extensively under these conditions. The levels of these two major RNA classes are considered to be strongly coregulated at the level of transcription. We demonstrate that E. coli can control the ratio of tRNAs per ribosome under starvation by means of differential degradation rates. The question of tRNA stability in stressed E. coli cells has become subject to debate. Our in-depth analysis of RNA quantification methods reveals hidden technical pitfalls at every step of the analysis, from RNA extraction to target detection and normalization. Most importantly, starved E. coli populations were more resilient to RNA extraction than unstarved populations. The current results underscore that the seemingly trivial task of quantifying an abundant RNA species is not straightforward for cells cultured outside the exponential growth regime.
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Yang J, Barra JT, Fung DK, Wang JD. Bacillus subtilis produces (p)ppGpp in response to the bacteriostatic antibiotic chloramphenicol to prevent its potential bactericidal effect. MLIFE 2022; 1:101-113. [PMID: 38817674 PMCID: PMC10989873 DOI: 10.1002/mlf2.12031] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 05/24/2022] [Indexed: 06/01/2024]
Abstract
Antibiotics combat bacteria through their bacteriostatic (by growth inhibition) or bactericidal (by killing bacteria) action. Mechanistically, it has been proposed that bactericidal antibiotics trigger cellular damage, while bacteriostatic antibiotics suppress cellular metabolism. Here, we demonstrate how the difference between bacteriostatic and bactericidal activities of the antibiotic chloramphenicol can be attributed to an antibiotic-induced bacterial protective response: the stringent response. Chloramphenicol targets the ribosome to inhibit the growth of the Gram-positive bacterium Bacillus subtilis. Intriguingly, we found that chloramphenicol becomes bactericidal in B. subtilis mutants unable to produce (p)ppGpp. We observed a similar (p)ppGpp-dependent bactericidal effect of chloramphenicol in the Gram-positive pathogen Enterococcus faecalis. In B. subtilis, chloramphenicol treatment induces (p)ppGpp accumulation through the action of the (p)ppGpp synthetase RelA. (p)ppGpp subsequently depletes the intracellular concentration of GTP and antagonizes GTP action. This GTP regulation is critical for preventing chloramphenicol from killing B. subtilis, as bypassing (p)ppGpp-dependent GTP regulation potentiates chloramphenicol killing, while reducing GTP synthesis increases survival. Finally, chloramphenicol treatment protects cells from the classical bactericidal antibiotic vancomycin, reminiscent of the clinical phenomenon of antibiotic antagonism. Taken together, our findings suggest a role of (p)ppGpp in the control of the bacteriostatic and bactericidal activity of antibiotics in Gram-positive bacteria, which can be exploited to potentiate the efficacy of existing antibiotics.
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Affiliation(s)
- Jin Yang
- Department of BacteriologyUniversity of WisconsinMadisonUSA
| | | | - Danny K. Fung
- Department of BacteriologyUniversity of WisconsinMadisonUSA
| | - Jue D. Wang
- Department of BacteriologyUniversity of WisconsinMadisonUSA
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5
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Identification and Characterization of Pleiotropic High-Persistence Mutations in the Beta Subunit of the Bacterial RNA Polymerase. Antimicrob Agents Chemother 2021; 65:e0052221. [PMID: 34424038 DOI: 10.1128/aac.00522-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations conferring resistance to bactericidal antibiotics reduce the average susceptibility of mutant populations. It is unknown, however, how those mutations affect the survival of individual bacteria. Since surviving bacteria can be a reservoir for recurring infections, it is important to know how survival rates may be affected by resistance mutations and by the choice of antibiotics. Here, we present evidence that (i) Escherichia coli mutants with 100 to 1,000 times increased frequency of survival in ciprofloxacin, an archetypal fluoroquinolone antibiotic, can be readily obtained in a stepwise selection; (ii) the high survival frequency is conferred by mutations in the switch region of the beta subunit of the RNA polymerase; (iii) the switch-region mutations are (p)ppGpp mimics, partially analogous to rpoB stringent mutations; (iv) the stringent and switch region rpoB mutations frequently occur in clinical isolates of E. coli, Acinetobacter baumannii, Mycobacterium tuberculosis, and Staphylococcus aureus, and at least one of them, RpoB S488L, which is a common rifampicin resistance mutations, dramatically increases the survival of a clinical methicillin-resistant S. aureus (MRSA) strain in ampicillin; and (v) the RpoB-associated high-survival phenotype can be reversed by subinhibitory concentrations of chloramphenicol.
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Cardoza E, Singh H. C Group-Mediated Antibiotic Stress Mimics the Cold Shock Response. Curr Microbiol 2021; 78:3372-3380. [PMID: 34283283 DOI: 10.1007/s00284-021-02613-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 07/12/2021] [Indexed: 11/26/2022]
Abstract
A temperature downshift results in stabilized secondary structure formation in mRNA that halts translation to which Escherichia coli responds by synthesizing a set of proteins termed as cold shock proteins (Csps). To cope with the sudden temperature drop, gene expression patterns are reprogrammed to induce Csps at the cost of other proteins. Out of the nine homologous proteins in the CspA family, CspA, CspB, CspG, and CspI have major roles in protecting the cell under a cold shock. Additionally, a subset of Csps has conferred the organism an ability to adapt to various stresses along the lines of nutrient deprivation, oxidative, heat, acid, and antibiotic stresses. Stressors like C group translational inhibitors stall the translational apparatus and produce a response similar to that observed under a temperature downshift. Conditions set by the antibiotic therefore elicit a cold shock response and induce the major Csps, thereby pointing out to a common mechanism existing between the two. In the current review, we briefly describe the induction of E. coli Csps under an antibiotic stress acquired from data published previously and help establish the role of Csps in protecting the cell against the inducing agents and as a participant in the organisms' complex stress response network.
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Affiliation(s)
- Evieann Cardoza
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Vile Parle (West), Mumbai, India
| | - Harinder Singh
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Vile Parle (West), Mumbai, India.
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7
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HPLC-based quantification of bacterial housekeeping nucleotides and alarmone messengers ppGpp and pppGpp. Sci Rep 2017; 7:11022. [PMID: 28887466 PMCID: PMC5591245 DOI: 10.1038/s41598-017-10988-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/17/2017] [Indexed: 02/02/2023] Open
Abstract
Here we describe an HPLC-based method to quantify bacterial housekeeping nucleotides and the signaling messengers ppGpp and pppGpp. We have replicated and tested several previously reported HPLC-based approaches and assembled a method that can process 50 samples in three days, thus making kinetically resolved experiments feasible. The method combines cell harvesting by rapid filtration, followed by acid extraction, freeze-drying with chromatographic separation. We use a combination of C18 IPRP-HPLC (GMP unresolved and co-migrating with IMP; GDP and GTP; AMP, ADP and ATP; CTP; UTP) and SAX-HPLC in isocratic mode (ppGpp and pppGpp) with UV detection. The approach is applicable to bacteria without the requirement of metabolic labelling with 32P-labelled radioactive precursors. We applied our method to quantify nucleotide pools in Escherichia coli BW25113 K12-strain both throughout the growth curve and during acute stringent response induced by mupirocin. While ppGpp and pppGpp levels vary drastically (40- and ≥8-fold, respectively) these changes are decoupled from the quotients of the housekeeping pool and guanosine and adenosine housekeeping nucleotides: NTP/NDP/NMP ratio remains stable at 6/1/0.3 during both normal batch culture growth and upon acute amino acid starvation.
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8
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Differential responses of Bacillus subtilis rRNA promoters to nutritional stress. J Bacteriol 2010; 193:723-33. [PMID: 21097612 DOI: 10.1128/jb.00708-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vivo expression levels of four rRNA promoter pairs (rrnp(1)p(2)) of Bacillus subtilis were determined by employing single-copy lacZ fusions integrated at the amyE locus. The rrnO, rrnJ, rrnD, and rrnB promoters displayed unique growth rate regulation and stringent responses. Both lacZ activity and mRNA levels were highest for rrnO under all growth conditions tested, while rrnJ, rrnB, and rrnD showed decreasing levels of activity. During amino acid starvation induced by serine hydroxamate (SHX), only the strong rrnO and rrnJ promoters demonstrated stringent responses. Under the growth conditions used, the rrn promoters showed responses similar to the responses to carbon source limitation induced by α-methyl glucoside (α-MG). The ratio of P2 to P1 transcripts, determined by primer extension analysis, was high for the strong rrnO and rrnJ promoters, while only P2 transcripts were detected for the weak rrnD and rrnB promoters. Cloned P1 or P2 promoter fragments of rrnO or rrnJ were differentially regulated. In wild-type (relA(+)) and suppressor [relA(S)] strains under the conditions tested, only P2 responded to carbon source limitation by a decrease in RNA synthesis, correlating with an increase in (p)ppGpp levels and a decrease in the GTP concentration. The weak P1 promoter elements remain relaxed in the three genetic backgrounds [relA(+), relA, relA(S)] in the presence of α-MG. During amino acid starvation, P2 was stringently regulated in relA(+) and relA(S) cells, while only rrnJp(1) was also regulated, but to a lesser extent. Both the relA(+) and relA(S) strains showed (p)ppGpp accumulation after α-MG treatment but not after SHX treatment. These data reveal the complex nature of B. subtilis rrn promoter regulation in response to stress, and they suggest that the P2 promoters may play a more prominent role in the stringent response.
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Sun D, Lee G, Lee JH, Kim HY, Rhee HW, Park SY, Kim KJ, Kim Y, Kim BY, Hong JI, Park C, Choy HE, Kim JH, Jeon YH, Chung J. A metazoan ortholog of SpoT hydrolyzes ppGpp and functions in starvation responses. Nat Struct Mol Biol 2010; 17:1188-94. [PMID: 20818390 DOI: 10.1038/nsmb.1906] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 07/13/2010] [Indexed: 12/26/2022]
Abstract
In nutrient-starved bacteria, RelA and SpoT proteins have key roles in reducing cell growth and overcoming stresses. Here we identify functional SpoT orthologs in metazoa (named Mesh1, encoded by HDDC3 in human and Q9VAM9 in Drosophila melanogaster) and reveal their structures and functions. Like the bacterial enzyme, Mesh1 proteins contain an active site for ppGpp hydrolysis and a conserved His-Asp-box motif for Mn(2+) binding. Consistent with these structural data, Mesh1 efficiently catalyzes hydrolysis of guanosine 3',5'-diphosphate (ppGpp) both in vitro and in vivo. Mesh1 also suppresses SpoT-deficient lethality and RelA-induced delayed cell growth in bacteria. Notably, deletion of Mesh1 (Q9VAM9) in Drosophila induces retarded body growth and impaired starvation resistance. Microarray analyses reveal that the amino acid-starved Mesh1 null mutant has highly downregulated DNA and protein synthesis-related genes and upregulated stress-responsible genes. These data suggest that metazoan SpoT orthologs have an evolutionarily conserved function in starvation responses.
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Affiliation(s)
- Dawei Sun
- Division of Magnetic Resonance, Korea Basic Science Institute, Chungbuk, South Korea
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10
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Marguet P, Tanouchi Y, Spitz E, Smith C, You L. Oscillations by minimal bacterial suicide circuits reveal hidden facets of host-circuit physiology. PLoS One 2010; 5:e11909. [PMID: 20689598 PMCID: PMC2912849 DOI: 10.1371/journal.pone.0011909] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 07/02/2010] [Indexed: 01/03/2023] Open
Abstract
Synthetic biology seeks to enable programmed control of cellular behavior though engineered biological systems. These systems typically consist of synthetic circuits that function inside, and interact with, complex host cells possessing pre-existing metabolic and regulatory networks. Nevertheless, while designing systems, a simple well-defined interface between the synthetic gene circuit and the host is frequently assumed. We describe the generation of robust but unexpected oscillations in the densities of bacterium Escherichia coli populations by simple synthetic suicide circuits containing quorum components and a lysis gene. Contrary to design expectations, oscillations required neither the quorum sensing genes (luxR and luxI) nor known regulatory elements in the PluxI promoter. Instead, oscillations were likely due to density-dependent plasmid amplification that established a population-level negative feedback. A mathematical model based on this mechanism captures the key characteristics of oscillations, and model predictions regarding perturbations to plasmid amplification were experimentally validated. Our results underscore the importance of plasmid copy number and potential impact of “hidden interactions” on the behavior of engineered gene circuits - a major challenge for standardizing biological parts. As synthetic biology grows as a discipline, increasing value may be derived from tools that enable the assessment of parts in their final context.
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Affiliation(s)
- Philippe Marguet
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Yu Tanouchi
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Eric Spitz
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Cameron Smith
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
- Institute for Genome Sciences and Policy, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Boehm A, Steiner S, Zaehringer F, Casanova A, Hamburger F, Ritz D, Keck W, Ackermann M, Schirmer T, Jenal U. Second messenger signalling governs Escherichia coli biofilm induction upon ribosomal stress. Mol Microbiol 2009; 72:1500-16. [PMID: 19460094 DOI: 10.1111/j.1365-2958.2009.06739.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Biofilms are communities of surface-attached, matrix-embedded microbial cells that can resist antimicrobial chemotherapy and contribute to persistent infections. Using an Escherichia coli biofilm model we found that exposure of bacteria to subinhibitory concentrations of ribosome-targeting antibiotics leads to strong biofilm induction. We present evidence that this effect is elicited by the ribosome in response to translational stress. Biofilm induction involves upregulation of the polysaccharide adhesin poly-beta-1,6-N-acetyl-glucosamine (poly-GlcNAc) and two components of the poly-GlcNAc biosynthesis machinery, PgaA and PgaD. Poly-GlcNAc control depends on the bacterial signalling molecules guanosine-bis 3', 5'(diphosphate) (ppGpp) and bis-(3'-5')-cyclic di-GMP (c-di-GMP). Treatment with translation inhibitors causes a ppGpp hydrolase (SpoT)-mediated reduction of ppGpp levels, resulting in specific derepression of PgaA. Maximal induction of PgaD and poly-GlcNAc synthesis requires the production of c-di-GMP by the dedicated diguanylate cyclase YdeH. Our results identify a novel regulatory mechanism that relies on ppGpp signalling to relay information about ribosomal performance to the Pga machinery, thereby inducing adhesin production and biofilm formation. Based on the important synergistic roles of ppGpp and c-di-GMP in this process, we suggest that interference with bacterial second messenger signalling might represent an effective means for biofilm control during chronic infections.
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Affiliation(s)
- Alex Boehm
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.
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12
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Zhang X, Liang ST, Bremer H. Feedback control of ribosome synthesis in Escherichia coli is dependent on eight critical amino acids. Biochimie 2006; 88:1145-55. [PMID: 16675089 DOI: 10.1016/j.biochi.2006.03.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Accepted: 03/30/2006] [Indexed: 11/23/2022]
Abstract
When bacteria growing in minimal medium are supplied with exogenous amino acids, they respond by increasing the synthesis of ribosomes; this leads to more protein synthesis capacity and faster growth. To examine how amino acids control the synthesis of ribosomes, two strategies were used. First, single amino acids were added to bacteria growing in minimal medium and their effect on the relative strength of the rrnB P1 promoter was determined. The addition of any one of eight amino acids (alanine, glutamine, and glutamic acid, isoleucine, leucine, methionine, serine, valine) increased the strength of the P1 promoter by 1.25- to 2.0-fold with no appreciable effect on transcription from an isolated rrn P2 promoter or on the bacterial growth rate. The effects of adding combinations of these critical amino acids were partially additive. When any one of the other amino acids was added, no discernable stimulation in relative P1 expression or growth was observed. In the second strategy, all amino acids were present in the growth medium, but the carbon source was altered to change the growth rate. In this case the relative strength of the P1 promoter was always constant and maximal. We suggest that addition of any of the eight critical amino acids reduces the ppGpp synthesis activity of the spoT gene product; the lower ppGpp levels, in turn, increase the strength of the rrn P1 promoters. It is suggested that these amino acids are involved in a feedback chain of reactions that control the rate of ribosome function by adjusting the rate of ribosome synthesis.
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Affiliation(s)
- Xiangyang Zhang
- Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75083-0688, USA.
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Abstract
Microcins are ribosomally encoded small peptide antibiotics produced by Gram(-) enterobacteria. Microcin production-biosynthesis, maturation and secretion to the medium-is encoded by gene clusters organized in operons. Production of the best known plasmid-encoded microcins (MccB, MccC and MccJ) switches on when cells reach the stationary growth phase. This production is doubly regulated at transcriptional level by (a). the growth phase: microcin operons silent/repressed during exponential growth are induced/derepressed when cells sense nutrient starvation and stop exponential growth, and (b). global bacterial regulators acting as inducers or repressors of operon expression. The role played by these regulators (CRP, EmrR, IHF, H-NS, LRP, OmpR, Sigma-38 and SpoT) in the expression of specific microcin operons is reviewed.
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Affiliation(s)
- Felipe Moreno
- Unidad de Genética Molecular, Hospital Ramón y Cajal, Ctra Colmenar Km 9 1, 28034, Madrid, Spain.
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14
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Chiuchiolo MJ, Delgado MA, Farías RN, Salomón RA. Growth-phase-dependent expression of the cyclopeptide antibiotic microcin J25. J Bacteriol 2001; 183:1755-64. [PMID: 11160108 PMCID: PMC95062 DOI: 10.1128/jb.183.5.1755-1764.2001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microcin J25 is a 2,107-Da, plasmid-encoded, cyclopeptide antibiotic produced by Escherichia coli. We have isolated lacZ fusions to mcjA (encoding the 58-amino-acid microcin precursor) and mcjB and mcjC (which are required for microcin maturation), and the regulation of these fusions was used to identify factors that control the expression of these genes. The mcjA gene was found to be dramatically induced as cells entered the stationary phase. Expression of mcjA could be induced by resuspending uninduced exponential-phase cells in spent supernatant obtained from an early-stationary-phase culture. Induction of mcjA expression was not dependent on high cell density, pH changes, anaerobiosis, or the buildup of some inducer. A starvation for carbon and inorganic phosphate induced mcjA expression, while under nitrogen limitation there was no induction at all. These results taken together suggest that stationary-phase induction of mcjA is triggered by nutrient depletion. The mcjB and mcjC genes were also regulated by the growth phase of the culture, but in contrast to mcjA, they showed substantial expression already during exponential growth. Induction of the microcin genes was demonstrated to be independent of RpoS, the cyclic AMP-Crp complex, OmpR, and H-NS. Instead, we found that the growth-phase-dependent expression of mcjA, mcjB, and mcjC may be explained by the concerted action of the positively acting transition state regulators ppGpp, Lrp, and integration host factor. Measurements of microcin J25 production by strains defective in these global regulators showed a good correlation with the reduced expression of the fusions in such mutant backgrounds.
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Affiliation(s)
- M J Chiuchiolo
- Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas, 4000 San Miguel de Tucumán, Tucumán, Argentina
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15
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Mechold U, Malke H. Characterization of the stringent and relaxed responses of Streptococcus equisimilis. J Bacteriol 1997; 179:2658-67. [PMID: 9098065 PMCID: PMC179016 DOI: 10.1128/jb.179.8.2658-2667.1997] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The 739-codon rel(Seq) gene of Streptococcus equisimilis H46A is bifunctional, encoding a strong guanosine 3',5'-bis(diphosphate) 3'-pyrophosphohydrolase (ppGppase) and a weaker ribosome-independent ATP:GTP 3'-pyrophosphoryltransferase [(p)ppGpp synthetase]. To analyze the function of this gene, (p)ppGpp accumulation patterns as well as protein and RNA synthesis were compared during amino acid deprivation and glucose exhaustion between the wild type and an insertion mutant carrying a rel(Seq) gene disrupted at codon 216. We found that under normal conditions, both strains contained basal levels of (p)ppGpp. Amino acid deprivation imposed by pseudomonic acid or isoleucine hydroxamate triggered a rel(Seq)-dependent stringent response characterized by rapid (p)ppGpp accumulation at the expense of GTP and abrupt cessation of net RNA accumulation in the wild type but not in the mutant. Tetracycline added to block (p)ppGpp synthesis caused the accumulated (p)ppGpp to degrade rapidly, with a concomitant increase of the GTP pool (decay constant of ppGpp, approximately 0.7 min(-1)). Simultaneous addition of pseudomonic acid and tetracycline to mimic a relaxed response caused wild-type RNA synthesis to proceed at rates approximating those seen under either condition in the mutant. Glucose exhaustion provoked the (p)ppGpp accumulation response in both the wild type and the rel(Seq) insertion mutant, consistent with the block of net RNA accumulation in both strains. Although the source of (p)ppGpp synthesis during glucose exhaustion remains to be determined, these findings reinforce the idea entertained previously that rel(Seq) fulfils functions that reside separately in the paralogous reL4 and spoT genes of Escherichia coli. Analysis of (p)ppGpp accumulation patterns was complicated by finding an unknown phosphorylated compound that comigrated with ppGpp under two standard thin-layer chromatography conditions. Unlike ppGpp, this compound did not adsorb to charcoal and did not accumulate appreciably during isoleucine deprivation. Like ppGpp, the unknown compound did accumulate during energy source starvation.
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Affiliation(s)
- U Mechold
- Institute for Molecular Biology, Jena University, Germany
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16
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Wright BE, Minnick MF. Reversion rates in a leuB auxotroph of Escherichia coli K-12 correlate with ppGpp levels during exponential growth. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 3):847-854. [PMID: 9084168 DOI: 10.1099/00221287-143-3-847] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Two isogenic strains of Escherichia coli K-12 differing only in relA, as well as two spoT transductants of the relA- strain, were examined with respect to ppGpp levels and reversion rates of a leuB- allele under nine different conditions. A positive correlation was established between reversion rates and the steady-state concentration of ppGpp during exponential growth. The leuB genes from two leuB- strains (isogenic except for relA) were cloned and sequenced and found to contain a single mutation, namely, a C-to-T transition at nucleotide 857. This mutation resulted in a serine-to-leucine substitution at amino acid residue 286 of the LeuB protein. PCR products that encompassed the leuB lesion were generated from 53 revertants and then sequenced. Of these revertants, 36 were found to contain nucleotide substitutions that would result in a serine (wild type), valine or methionine at amino acid residue 286 of LeuB, and nearly all of them exhibited generation times similar to wild type. Seventeen of the analysed revertants were found to be suppressors that retained the encoded leucine at residue 286. The majority of the suppressor mutants exhibited generation times that were significantly longer than wild type.
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Affiliation(s)
| | - Michael F Minnick
- Division of Biological Sciences, The University of Montana, Missoula, Ml 59812-1002, USA
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17
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Mechold U, Cashel M, Steiner K, Gentry D, Malke H. Functional analysis of a relA/spoT gene homolog from Streptococcus equisimilis. J Bacteriol 1996; 178:1401-11. [PMID: 8631718 PMCID: PMC177815 DOI: 10.1128/jb.178.5.1401-1411.1996] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We examined the functional attributes of a gene encountered by sequencing the streptokinase gene region of Streptococcus equisimilis H46A. This gene, originally called rel, here termed relS. equisimilis, is homologous to two related Escherichia coli genes, spoT and relA, that function in the metabolism of guanosine 5',3'-polyphosphates [(p)ppGpp]. Studies with a variety of E. coli mutants led us to deduce that the highly expressed rel S. equisimilis gene encodes a strong (p)ppGppase and a weaker (p)ppGpp synthetic activity, much like the spoT gene, with a net effect favoring degradation and no complementation of the absence of the relA gene. We verified that the Rel S. equisimilis protein, purified from an E. coli relA spoT double mutant, catalyzed a manganese-activated (p)ppGpp 3'-pyrophosphohydrolase reaction similar to that of the SpoT enzyme. This Rel S. equisimilis protein preparation also weakly catalyzed a ribosome-independent synthesis of (p)ppGpp by an ATP to GTP 3'-pyrophosphoryltransferase reaction when degradation was restricted by the absence of manganese ions. An analogous activity has been deduced for the SpoT protein from genetic evidence. In addition, the Rel S. equisimilis protein displays immunological cross-reactivity with polyclonal antibodies specific for SpoT but not for RelA. Despite assignment of rel S. equisimilis gene function in E. coli as being similar to that of the native spoT gene, disruptions of rel S. equisimilis in S. equisimilis abolish the parental (p)ppGpp accumulation response to amino acid starvation in a manner expected for relA mutants rather than spoT mutants.
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Affiliation(s)
- U Mechold
- Institute for Molecular Biology, Jena University, Germany
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18
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Nakayashiki T, Nishimura K, Tanaka R, Inokuchi H. Partial inhibition of protein synthesis accelerates the synthesis of porphyrin in heme-deficient mutants of Escherichia coli. MOLECULAR & GENERAL GENETICS : MGG 1995; 249:139-46. [PMID: 7500934 DOI: 10.1007/bf00290359] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mutants of Escherichia coli defective in the HemA protein grow extremely poorly as the result of heme deficiency. A novel hemA mutant was identified whose rate of growth was dramatically enhanced by addition to the medium of low concentrations of translational inhibitors, such as chloramphenicol and tetracycline. This mutant (H110) carries mutation at position 314 in the hemA gene, which resulted in diminished activity of the encoded protein. Restoration of growth of H110 upon addition of the drugs mentioned above was due to activation of the synthesis of porphyrin. However, this activation was not characteristic exclusively of cells with this mutant hemA gene since it was also observed in a heme-deficient strain bearing the wild-type hemA gene. The activation did not depend on the promoter activity of the hemA gene, as indicated by studies with fusion genes. It appears that partial inhibition of protein synthesis via inhibition of peptidyltransferase can promote the synthesis of porphyrin by providing an increased supply of glutamyl-tRNA for porphyrin synthesis. Glutamyl-tRNA is the common substrate for peptidyltransferase and HemA.
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Affiliation(s)
- T Nakayashiki
- Department of Biophysics, Faculty of Science, Kyoto University, Japan
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19
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Cassels R, Oliva B, Knowles D. Occurrence of the regulatory nucleotides ppGpp and pppGpp following induction of the stringent response in staphylococci. J Bacteriol 1995; 177:5161-5. [PMID: 7665499 PMCID: PMC177300 DOI: 10.1128/jb.177.17.5161-5165.1995] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The stringent response in Escherichia coli and many other organisms is regulated by the nucleotides ppGpp and pppGpp. We show here for the first time that at least six staphylococcal species also synthesize ppGpp and pppGpp upon induction of the stringent response by mupirocin. Spots corresponding to ppGpp and pppGpp on thin-layer chromatograms suggest that pppGpp is the principal regulatory nucleotide synthesized by staphylococci in response to mupirocin, rather than ppGpp as in E. coli.
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Affiliation(s)
- R Cassels
- Department of Microbial Metabolism and Biochemistry, SmithKline Beecham Pharmaceuticals, Brockham Park, Betchworth, Surrey, United Kingdom
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20
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Abstract
The SpoT protein of Escherichia coli serves as a source of degradation as well as an apparent source of synthesis of (p)ppGpp. Since the subcellular localization of SpoT might be a clue to its function, we have used SpoT-specific antisera to analyze cell extracts fractionated on sucrose gradients. We find that the SpoT protein is not bound to ribosomes or to either inner or outer membrane fractions. Although the SpoT protein is found in large aggregates, its localization is probably cytosolic.
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Affiliation(s)
- D R Gentry
- Section on Molecular Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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21
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Xiao H, Kalman M, Ikehara K, Zemel S, Glaser G, Cashel M. Residual guanosine 3‘,5‘-bispyrophosphate synthetic activity of relA null mutants can be eliminated by spoT null mutations. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67694-5] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Guanosine tetraphosphate (ppGpp) dependence of the growth rate control of rrnB P1 promoter activity in Escherichia coli. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38441-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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23
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Bulthuis BA, Koningstein GM, Stouthamer AH, van Verseveld HW. A comparison between aerobic growth of Bacillus licheniformis in continuous culture and partial-recycling fermentor, with contributions to the discussion on maintenance energy demand. Arch Microbiol 1989. [DOI: 10.1007/bf00446937] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Protein Sequences Encoded by the relA and the spoT Genes of Escherichia coli Are Interrelated. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)60500-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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25
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Walderich B, Ursinus-Wössner A, van Duin J, Höltje JV. Induction of the autolytic system of Escherichia coli by specific insertion of bacteriophage MS2 lysis protein into the bacterial cell envelope. J Bacteriol 1988; 170:5027-33. [PMID: 3053640 PMCID: PMC211567 DOI: 10.1128/jb.170.11.5027-5033.1988] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacterial lysis induced by the expression of the cloned lysis gene of the RNA bacteriophage MS2 in Escherichia coli was shown to be under the same regulatory control mechanisms as penicillin-induced lysis. It was controlled by the stringent response and showed the phenomenon of tolerance when E. coli was grown at pH 5. Changes in the fine structure of the murein were found to be the earliest physiological changes in the cell, taking place 10 min before the onset of cellular lysis and inhibition of murein synthesis. Both the average length of the glycan strands and, with a time lag, the degree of cross-linkage were altered, indicating that a lytic transglycosylase and a DD-endopeptidase had been triggered. After extensive separation of the membranes by isopycnic sucrose gradient centrifugation, the lysis protein was present predominantly in the cytoplasmic membrane and in a fraction of intermediate density and, to a lesser degree, in the outer membrane, irrespective of the conditions of growth. However, only under lysis-permissive conditions could a 17% increase in the number of adhesion sites between the inner and outer membranes be observed. Thus, a casual relationship between lysis and the formation of lysis protein-induced adhesion sites seems to exist.
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Affiliation(s)
- B Walderich
- Abteilung Biochemie, Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Federal Republic of Germany
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26
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Sarubbi E, Rudd KE, Cashel M. Basal ppGpp level adjustment shown by new spoT mutants affect steady state growth rates and rrnA ribosomal promoter regulation in Escherichia coli. MOLECULAR & GENERAL GENETICS : MGG 1988; 213:214-22. [PMID: 2460731 DOI: 10.1007/bf00339584] [Citation(s) in RCA: 138] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This work describes an approach towards analyzing the regulatory effects of variation of guanosine 3',5'-bispyrophosphate (ppGpp) basal levels in Escherichia coli during steady state growth. A series of strains was derived by mutating the spoT gene (which encodes the major cellular ppGppase) so as to obtain systematic increments in ppGpp basal levels. These strains differ genetically at the spoT locus and, in some cases, also at the relA locus because of the severity of spoT mutant alleles. Measurements of ppGpp revealed a ten-fold range of basal levels during growth on minimal medium. The empirical relationship between ppGpp concentration and growth rate is a simple linear inverse correlation. Tandem rrnA ribosomal RNA promoters, present on a multicopy plasmid, are shown to be differentially regulated over this range of basal levels. The upstream P1 promoter activity shows an inverse exponential relation to ppGpp concentration whereas the downstream P2 promoter is only weakly affected. We conclude that there are systematic regulatory consequences associated with small changes in ppGpp basal levels during steady state growth that probably are part of a continuum with more dramatic effects observed during the stringent response to amino acid deprivation.
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Affiliation(s)
- E Sarubbi
- Section of Molecular Regulation, National Institute of Child Health and Human Development, Bethesda, MD 20892
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27
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Mackow ER, Chang FN. Correlation between RNA synthesis and ppGpp content in Escherichia coli during temperature shifts. MOLECULAR & GENERAL GENETICS : MGG 1983; 192:5-9. [PMID: 6196606 DOI: 10.1007/bf00327639] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Both a correlation and a lack of correlation between guanosine 5'-diphosphate, 3'-diphosphate (ppGpp) level and RNA accumulation have been reported during temperature shifts of E. coli. We have reexamined these phenomena by measuring the total rate of RNA synthesis. After a temperature upshift (23 degrees to 40 degrees C) of E. coli relA+ and relA1 strains, there is an immediate increase in the rate of RNA synthesis which corresponds with the observed in vitro effects of temperature on RNA synthesis (Mangel 1974; Travers 1974). A subsequent increase in ppGpp level is correlated with a decrease in the rate of RNA synthesis. Conversely, following a temperature downshift (40 degrees to 23 degrees C), both relA+ and relA1 bacteria show an immediate decrease in the rate of RNA synthesis. Subsequently all strains studied decrease ppGpp content and correspondingly increase the rate of RNA synthesis after a downshift. By measuring the rate of RNA synthesis we have separated immediate temperature-induced changes in RNA synthesis, from the apparent effects of ppGpp during temperature shifts. As a result, during temperature upshifts and downshifts of relA+, and relA1 bacteria, an inverse correlation between ppGpp content and the total rate of RNA synthesis does exist. The fact that both relA+ and relA1 strains show similar responses to temperature shifts provides additional evidence for the function of relA-independent basal level ppGpp synthesis in regulating RNA synthesis in E. coli.
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28
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Robakis NK, Rossman TG, Shapiro R, Szer W. The effects of bisulfite on growth and macromolecular synthesis in Escherichia coli. Chem Biol Interact 1983; 43:289-98. [PMID: 6402316 DOI: 10.1016/0009-2797(83)90113-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Bisulfite reversibly inhibits the growth of a variety of microorganisms and has been used as a preservative in foods and beverages for that reason. We have now measured macromolecule synthesis in Escherichia coli K12 after bisulfite treatment. RNA synthesis, the synthesis of total protein, and of an inducible enzyme, beta-galactosidase, stopped almost immediately upon addition of 2 mM (or higher concentrations) of bisulfite. These functions resumed after a lag whose duration depended on the concentration of bisulfite added. The synthesis of DNA was slowed upon bisulfite addition, but did not stop entirely. The inhibition of RNA synthesis by bisulfite took place in both stringent and relaxed strains of E. coli and was not relieved upon addition of chloramphenicol. Stringent control was therefore not involved in this effect. No effect on protein synthesis was observed in the cell-free system of E. coli (using poly(U) or MS2 RNA as messenger) at bisulfite concentrations up to 10 mM. Protein synthesis inhibition in vivo was apparently not due to a reaction of bisulfite with a component of this system. In additional experiments, RNA polymerase was not impaired by bisulfite, and the growth inhibition effect was shown to proceed in the presence of inhibitors of free radical chain reactions.
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29
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Riedel K. [Nucleoside polyphosphates: occurrence, metabolism and function]. ZEITSCHRIFT FUR ALLGEMEINE MIKROBIOLOGIE 1983; 23:103-41. [PMID: 6346704 DOI: 10.1002/jobm.3630230206] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Procaryotes have regulatory systems allowing to vary the metabolism in response to nutritional variations, to reduce the growth, and to start development. Nucleoside polyphosphates are mediators of coordinated alterations of metabolism. In this review, after a brief recall of the characteristics of the stringent response, the occurrence, determinations, and the metabolism of the nucleoside polyphosphates are presented. The representation of the pleiotropic effects includes the regulation of the protein synthesis and of the protein synthesis apparatus, of the protein turnover, of the N- and carbohydrate metabolism, of the formation of cell membranes and cell walls as well as the possible function of the development.
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30
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Graham MY, Tal M, Schlessinger D. lac Transcription in Escherichia coli cells treated with chloramphenicol. J Bacteriol 1982; 151:251-61. [PMID: 7045075 PMCID: PMC220234 DOI: 10.1128/jb.151.1.251-261.1982] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
When protein synthesis was blocked by chloramphenicol in vivo, transcription initiation of lac mRNA was severely inhibited. In a promoter mutant (L8-UV5) or in wild-type cells supplemented with adenosine 3',5'-phosphate (greater than or equal to 5 mM), nearly normal initiation could be achieved, and when the mRNA chains formed were extracted, they coded for the 5'-terminal alpha-peptide of the lacZ gene in vitro. However, even under such conditions, only a fraction of RNA polymerases proceeded to the end of the Z gene in the presence of chloramphenicol; as a consequence, a wide range of sizes of mRNA was produced, and very few transcripts were formed all the way to the natural termination site of the operon. In other words, premature transcription termination occurred in chloramphenicol-treated cells, as current models predict, but terminations occurred to variable extents at several intragenic sites and apparently at least one intergenic site. Termination at intragenic sites occurred far less in cells bearing a mutation in the transcription termination factor rho.
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31
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Davidson JP, Wilson DJ, Williams LS. Role of a hisU gene in the control of stable RNA synthesis in Salmonella typhimurium. J Mol Biol 1982; 157:237-64. [PMID: 6180170 DOI: 10.1016/0022-2836(82)90232-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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32
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Akinyanju JA, Smith RJ. Energy deprivation and guanosine 5'-diphosphate 3'-diphosphate synthesis in cyanobacteria. J Bacteriol 1982; 149:681-4. [PMID: 6799494 PMCID: PMC216559 DOI: 10.1128/jb.149.2.681-684.1982] [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: 01/21/2023] Open
Abstract
A reduction in the incident light intensity has been used to elicit guanosine 5'-diphosphate 3'-diphosphate accumulation in cyanobacteria. Inhibitors of photophosphorylation, 2,4-dinitrophenol, and carbonyl cyanide-m-chlorophenyl hydrazone elicited accumulation in three species of cyanobacteria when they were grown on dinitrogen or nitrate, but not in cultures grown on ammonium or glutamine. Accumulation of guanosine 5'-diphosphate 3'-diphosphate also preceded a substantial reduction of the purine nucleoside triphosphate pools. This accumulation of guanosine 5'-diphosphate 3'-diphosphate is therefore not primarily dependent upon reduced ATP concentration or proton gradient potential, but rather upon the source of combined nitrogen. In this respect, incident light step down is not comparable with nutritional step-down procedures in heterotrophic bacteria.
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33
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Correlation between RNA synthesis and basal level guanosine 5‘-diphosphate 3‘-diphosphate in relaxed mutants of Escherichia coli. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68454-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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34
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Lagosky PA, Chang FN. Influence of amino acid starvation on guanosine 5'-diphosphate 3'-diphosphate basal-level synthesis in Escherichia coli. J Bacteriol 1980; 144:499-508. [PMID: 6159345 PMCID: PMC294696 DOI: 10.1128/jb.144.2.499-508.1980] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We observed that the synthesis of basal-level guanosine 5'-diphosphate 3'-diphosphate (ppGpp) in both relA mutants and relA+ relC strains of Escherichia coli decreased in response to amino acid limitation and that this was accompanied by an increase in ribonucleic acid (RNA) synthesis. Addition of the required amino acid to starved cultures of relaxed bacteria resulted in the resumption of ppGpp synthesis and a concomitant decrease in RNA production. Our results indicate that relA mutants retain a stringent factor-independent ribosomal mechanism for basal-level ppGpp synthesis. They also suggest that in relA+ bacteria, stringent factor-mediated ppGpp synthesis and the production of basal-level ppGpp are mutually exclusive. These findings substantiate the hypothesis that there are two functionally discrete mechanisms for ppGpp synthesis in E. coli. Through these studies we have also obtained new evidence which indicates that ppGpp serves as a modulator of RNA synthesis during balanced growth as well as under conditions of nutritional downshift and starvation.
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35
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Mitchell J, Lucas-Lenard J. The effect of alcohols on guanosine 5‘-diphosphate-3‘-diphosphate metabolism in stringent and relaxed Escherichia coli. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43738-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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36
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Guanosine-5‘-diphosphate-3‘-diphosphate (ppGpp) and the regulation of protein breakdown in Escherichia coli. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)86133-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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37
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Tétu C, Dassa E, Boquet PL. The energy-dependent degradation of guanosine 5'-diphosphate 3'-diphosphate in Escherichia coli. Lack of correlation with ATP levels in vivo and role of the transmembrane proton gradient. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 103:117-24. [PMID: 6987054 DOI: 10.1111/j.1432-1033.1980.tb04295.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Different inhibitors of the energy metabolism have been assayed in Escherichia coli K12 for their ability to increase the level of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) as a consequence of a restriction of its degradation. Inhibitors of the respiration and uncouplers of oxidative phosphorylations had effects similar to carbon-source-induced downshifts while the ATPase inhibitor dicyclohexylcarbodiimide was less efficient. The effects of dicyclohexylcarbodiimide and of the uncoupler carbonylcyanide p-fluoro methoxyphenylhydrazone (FCCP) on ppGpp degradation were compared in a drug-permeable envelope mutant. At concentrations of inhibitors sufficient to deplete the pool of ATP by 50%, only FCCP was able to block ppGpp degradation. Moreover, FCCP also inhibited ppGpp degradation in a ATPase-deficient strain growing on glucose as carbon source while, as expected, it did not change the level of ATP. It is concluded, according to Mitchell's chemiosmotic hypothesis, that, in vivo, the integrity of the transmembrane proton gradient rather than the ATP pool size is a prerequisite for the normal processing of the energy-dependent degradation of ppGpp.
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38
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Nishino T, Gallant J, Shalit P, Palmer L, Wehr T. Regulatory nucleotides involved in the Rel function of Bacillus subtilis. J Bacteriol 1979; 140:671-9. [PMID: 115847 PMCID: PMC216696 DOI: 10.1128/jb.140.2.671-679.1979] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We have examined the accumulation of polyphosphorylated nucleotides in Bacillus subtilis in relation to the function of the rel gene. Our results are as follows. (i) During inhibition of isoleucine activation by O-methylthreonine, wildtype B. subtilis cells accumulate unusual nucleotides with the chromatographic and chemical properties of pppApp, ppApp, pppGpp, ppGpp, pGpp, and ppGp. (ii) During the carbon source downshift elicited by inhibiting glucose uptake, we observed accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iii) At the end of long phase in sporulation medium, we observed a small transient accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iv) We were unable to detect a nucleotide with chromatographic behavior expected for pppAppp under any conditions. (v) The rel mutant of Swanton and Edlin (Biochem. Biophys. Res. Commun. 46-583-588, 1972) did not accumulate any of these polyphosphorylated nucleotides under any of the conditions examined. (vi) the rel mutant is unimpaired in sporulation. We conclude that one or more of the nucleotides we have detected may be involved in controlling the specificity of transcription during the stringent response, but none of them are required for sporogenesis.
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39
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Johnson GS, Adler CR, Collins JJ, Court D. Role of the spoT gene product and manganese ion in the metabolism of guanosine 5‘-diphosphate 3‘-diphosphate in Escherichia coli. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50621-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Somerville CR, Ahmed A. Mutants of Escherichia coli defective in the degradation of guanosine 5'-triphosphate, 3'-diphosphate (pppGpp). MOLECULAR & GENERAL GENETICS : MGG 1979; 169:315-23. [PMID: 372753 DOI: 10.1007/bf00382277] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A new class of mutants of E. coli exhibiting altered metabolism of ppGpp and pppGpp has been isolated, and mapped at a locus designated gpp, near min 83 on the genetic map. These mutants accumulate elevated levels of pppGpp during amino acid starvation or carbon source downshift, and exhibit a reduced rate of pppGpp degradation in vivo. The in vitro evidence suggests that the gpp mutants are defective in a 5'-nucleotidase, which specifically hydrolyzes pppGpp to ppGpp. Certain combinations of gpp and spoT mutations are inviable. A gpp spoT double mutant, constructed by employing a leaky spoT mutation, was found to have a slower rate of pppGpp degradation than the gpp mutant alone. This result indicates that spoT also participates in pppGpp degradation. The inviability of certain gpp spoT combinations is attributed to the inability of the double mutants to degrade pppGpp. This is supported by the observation that selection for increased growth rate on the double mutant results in the recovery of relA mutations. Various effects of the gpp mutation upon the pppGpp and ppGpp pools provide additional support for a scheme in which pppGpp is the major precursor of ppGpp.
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41
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Heinemeyer EA, Richter D. Characterization of the guanosine 5'-triphosphate 3'-diphosphate and guanosine 5'-diphosphate 3'-diphosphate degradation reaction catalyzed by a specific pyrophosphorylase from Escherichia coli. Biochemistry 1978; 17:5368-72. [PMID: 365225 DOI: 10.1021/bi00618a007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Guanosine 5'-triphosphate 3'-diphosphate (pppGpp) and guanosine 5'-diphosphate 3'-diphosphate (ppGpp) are specifically degraded by a manganese-dependent pyrophosphorylase present in spoT+ but not in spoT- strains of Escherichia coli, indicating that the enzyme is the spoT gene product. The enzyme catalyzes the release of pyrophosphate from the 3' position of ppGpp or pppGpp, yielding ppG and pppG, respectively; pppGpp could not be detected as an intermediate in the decay reaction. Degradation of (p)ppGpp is optimal in the presence of 200 to 300 mM potassium or sodium acetate, at a pH of 7.5 to 8 and a temperature of 37 degrees C.
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42
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Lagosky PA, Chang FN. The extraction of guanosine 5'-diphosphate, 3'-diphosphate (ppGpp) from Escherichia coli using low pH reagents: a reevaluation. Biochem Biophys Res Commun 1978; 84:1016-24. [PMID: 31874 DOI: 10.1016/0006-291x(78)91685-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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43
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Botsford JL, Drexler M. The cyclic 3',5'-adenosine monophosphate receptor protein and regulation of cyclic 3',5'-adenosine monophosphate synthesis in Escherichia coli. MOLECULAR & GENERAL GENETICS : MGG 1978; 165:47-56. [PMID: 213702 DOI: 10.1007/bf00270375] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rates of synthesis of cyclic 3',5'-adenosine monophosphate (cAMP) were measured in cultures of Escherichia coli aerating without a carbon source. This technique provides a representative measure of adenylate cyclase activity in the absence of inhibition caused by transport of the carbon source. Adenylate cyclase activity was found to vary more than 20-fold depending on the carbon source that had been available during growth. Synthesis of cAMP in cells aerating in the absence of the carbon source was highest when cells had been grown with glucose or fructose which inhibit adenylate cyclase activity severely. Synthesis of cAMP was much lower when cells had been grown with glycerol or succinate which cause only minimal inhibition of the activity. The variation in cAMP synthesis due to different carbon sources requires a functional cAMP receptor protein (CRP). Crp- mutants synthesize cAMP at comparable rates regardless of the carbon source that afforded growth. A novel mutant of E. coli having a CRP no longer dependent on cAMP has been isolated and characterized. Adenylate cyclase activity in this mutant no longer responds normally to variations in the carbon source.
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44
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Harris JS, van Tassel E, Chaney SG. A mutation in Escherichia coli that mimics diauxie lag. Biochem Biophys Res Commun 1978; 82:982-9. [PMID: 358971 DOI: 10.1016/0006-291x(78)90880-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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45
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St John A, Goldberg A. Effects of reduced energy production on protein degradation, guanosine tetraphosphate, and RNA synthesis in Escherichia coli. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)40877-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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46
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Pao CC, Gallant J. A gene involved in the metabolic control of ppGpp synthesis. MOLECULAR & GENERAL GENETICS : MGG 1978; 158:271-7. [PMID: 342913 DOI: 10.1007/bf00267198] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A genetic locus has been identified which controls the basal synthesis of ppGpp in growing E. coli. Cells carrying a recessive allele of the relX gene have a very low concentration of ppGpp during balanced growth, and fail to accumulate ppGpp in response to carbon/energy source downshift. Moreover, the recessive relX allele renders the cells unable to grow at 42 degrees C and, when coupled with relA, makes the cells sensitive to the presence of leucine in minimal medium. RelX is cotransduced with fuc and relA and located at approximately 59.4 min on the E. coli genetic map.
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47
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Heinemeyer EA, Richter D. In vitro degradation of guanosine tetraphosphate (ppGpp) by an enzyme associated with the ribosomal fraction from Escherichia coli. FEBS Lett 1977; 84:357-61. [PMID: 340264 DOI: 10.1016/0014-5793(77)80724-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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48
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De Boer HA, Bakker AJ, Gruber M. Breakdown of ppGpp in spoT and spoT-cells of Escherichia coli. Manganese and energy requirement and tetracycline inhibition. FEBS Lett 1977; 79:19-24. [PMID: 330223 DOI: 10.1016/0014-5793(77)80341-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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49
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Shen V, Bremer H. Chloramphenicol-induced changes in the synthesis of ribosomal, transfer, and messenger ribonucleic acids in Escherichia coli B/r. J Bacteriol 1977; 130:1098-108. [PMID: 324974 PMCID: PMC235332 DOI: 10.1128/jb.130.3.1098-1108.1977] [Citation(s) in RCA: 53] [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 synthesis of ribosomal ribonucleic acid (rRNA), transfer RNA (tRNA) and messenger RNA (mRNA) was measured in Escherichia coli B/r after the addition of 100 mug of chloramphenicol (CAM) per ml to cultures growing either in one of three minimal media (succinate, glycerol, or glucose) or in one of the same three media supplemented with 20 amino acids. (i) During CAM treatment, rRNA and tRNA were synthesized in the same relative proportions (85:15) as during exponential growth. The faster accumulation of tRNA relative to rRNA in CAM was due to a decreased stability of rRNA that is synthesized in the presence of or immediately before the addition of CAM. (ii) CAM stimulated the synthesis of rRNA and tRNA two- to eightfold. The results fell into two groups; one group was from studies done in minimal media and the other was from amino acid-supplemented media. In each group the stimulation decreased with increasing growth rate of the culture during exponential growth before the addition of CAM; however, the stimulation in minimal media was lower than that in amino acid-supplemented media. (iii) CAM caused an increase in the proportion of rRNA and tRNA synthesis and a corresponding decrease in the proportion of mRNA synthesis. In minimal media, the residual proportion of mRNA synthesis after CAM treatment was 10 to 15% of total RNA synthesis; in amino acid-supplemented media this proportion was 0 to 10%. In either case, the residual proportion of mRNA synthesis was independent of the proportions observed during exponential growth in these media. (iv) The absolute rate of mRNA synthesis decreased severalfold with the addition of CAM; i.e., the rate of synthesis of rRNA and tRNA was increased at the expense of mRNA synthesis. (v) During exponential growth, the fraction of the instantaneous rate of total RNA synthesis that corresponds to mRNA is a function of both the growth rate and the presence or absence of amino acids in the growth medium: in the absence of amino acids, this fraction decreased with increasing growth rate; in the presence of amino acids, the fraction increased slightly with growth rate. These results are consistent with a regulation of rRNA and tRNA synthesis at the transcriptional level, e.g., with a CAM-induced increase in the affinity of RNA polymerase for the rRNA and tRNA promoters. The results also suggest the occurrence of a regulation of RNA polymerase enzyme activity, i.e., of an activation of RNA polymerase that is inactive during exponential growth. A distinction between these alternatives requires measurements of the rRNA chain growth rates during CAM treatment.
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50
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Smith R. The regulation of stable RNA synthesis in the blue-green alga Anacystis nidulans, the effect of DCMU inhibition. FEMS Microbiol Lett 1977. [DOI: 10.1111/j.1574-6968.1977.tb00597.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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