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Gueddouri D, Caüzac M, Fauveau V, Benhamed F, Charifi W, Beaudoin L, Rouland M, Sicherre F, Lehuen A, Postic C, Boudry G, Burnol AF, Guilmeau S. Insulin resistance per se drives early and reversible dysbiosis-mediated gut barrier impairment and bactericidal dysfunction. Mol Metab 2022; 57:101438. [PMID: 35007789 PMCID: PMC8814824 DOI: 10.1016/j.molmet.2022.101438] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/24/2021] [Accepted: 01/05/2022] [Indexed: 11/30/2022] Open
Abstract
Objective A common feature of metabolic diseases is their association with chronic low-grade inflammation. While enhanced gut permeability and systemic bacterial endotoxin translocation have been suggested as key players of this metaflammation, the mechanistic bases underlying these features upon the diabesity cascade remain partly understood. Methods Here, we show in mice that, independently of obesity, the induction of acute and global insulin resistance and associated hyperglycemia, upon treatment with an insulin receptor (IR) antagonist (S961), elicits gut hyperpermeability without triggering systemic inflammatory response. Results Of note, S961-treated diabetic mice display major defects of gut barrier epithelial functions, such as increased epithelial paracellular permeability and impaired cell-cell junction integrity. We also observed in these mice the early onset of a severe gut dysbiosis, as characterized by the bloom of pro-inflammatory Proteobacteria, and the later collapse of Paneth cells antimicrobial defense. Interestingly, S961 treatment discontinuation is sufficient to promptly restore both the gut microbial balance and the intestinal barrier integrity. Moreover, fecal transplant approaches further confirm that S961-mediated dybiosis contributes at least partly to the disruption of the gut selective epithelial permeability upon diabetic states. Conclusions Together, our results highlight that insulin signaling is an indispensable gatekeeper of intestinal barrier integrity, acting as a safeguard against microbial imbalance and acute infections by enteropathogens. S961-mediated insulin resistance elicits reversible gut leakiness in lean mice. Diabetic leaky gut is associated with reduced Paneth cells antimicrobial defenses. S961 treatment triggers early onset of pro-inflammatory gut microbial imbalance. S961-associated dysbiosis contributes to intestinal barrier integrity impairment.
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Affiliation(s)
- Dalale Gueddouri
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Michèle Caüzac
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Véronique Fauveau
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Fadila Benhamed
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Wafa Charifi
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Lucie Beaudoin
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Matthieu Rouland
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Florian Sicherre
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Agnès Lehuen
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Catherine Postic
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France
| | - Gaëlle Boudry
- Institut NuMeCan, INRAE, INSERM, Univ Rennes, F35000, Rennes, France
| | | | - Sandra Guilmeau
- Université de Paris, Institut Cochin, CNRS, INSERM, F75014, Paris, France.
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Selective Modification of Streptozotocin at the C3 Position to Improve Its Bioactivity as Antibiotic and Reduce Its Cytotoxicity towards Insulin-Producing β Cells. Antibiotics (Basel) 2020; 9:antibiotics9040182. [PMID: 32326389 PMCID: PMC7235802 DOI: 10.3390/antibiotics9040182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 03/31/2020] [Accepted: 04/10/2020] [Indexed: 01/26/2023] Open
Abstract
With the increasing resistance of bacteria to current antibiotics, novel compounds are urgently needed to treat bacterial infections. Streptozotocin (STZ) is a natural product that has broad-spectrum antibiotic activity, albeit with limited use because of its toxicity to pancreatic β cells. In an attempt to derivatize STZ through structural modification at the C3 position, we performed the synthesis of three novel STZ analogues by making use of our recently developed regioselective oxidation protocol. Keto-STZ (2) shows the highest inhibition of bacterial growth (minimum inhibitory concentration (MIC) and viability assays), but is also the most cytotoxic compound. Pre-sensitizing the bacteria with GlcNAc increased the antimicrobial effect, but did not result in complete killing. Interestingly, allo-STZ (3) revealed moderate concentration-dependent antimicrobial activity and no cytotoxicity towards β cells, and deoxy-STZ (4) showed no activity at all.
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3
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Benson RW, Norton MD, Lin I, Du Comb WS, Godoy VG. An active site aromatic triad in Escherichia coli DNA Pol IV coordinates cell survival and mutagenesis in different DNA damaging agents. PLoS One 2011; 6:e19944. [PMID: 21614131 PMCID: PMC3096655 DOI: 10.1371/journal.pone.0019944] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 04/07/2011] [Indexed: 12/16/2022] Open
Abstract
DinB (DNA Pol IV) is a translesion (TLS) DNA polymerase, which inserts a nucleotide opposite an otherwise replication-stalling N(2)-dG lesion in vitro, and confers resistance to nitrofurazone (NFZ), a compound that forms these lesions in vivo. DinB is also known to be part of the cellular response to alkylation DNA damage. Yet it is not known if DinB active site residues, in addition to aminoacids involved in DNA synthesis, are critical in alkylation lesion bypass. It is also unclear which active site aminoacids, if any, might modulate DinB's bypass fidelity of distinct lesions. Here we report that along with the classical catalytic residues, an active site "aromatic triad", namely residues F12, F13, and Y79, is critical for cell survival in the presence of the alkylating agent methyl methanesulfonate (MMS). Strains expressing dinB alleles with single point mutations in the aromatic triad survive poorly in MMS. Remarkably, these strains show fewer MMS- than NFZ-induced mutants, suggesting that the aromatic triad, in addition to its role in TLS, modulates DinB's accuracy in bypassing distinct lesions. The high bypass fidelity of prevalent alkylation lesions is evident even when the DinB active site performs error-prone NFZ-induced lesion bypass. The analyses carried out with the active site aromatic triad suggest that the DinB active site residues are poised to proficiently bypass distinctive DNA lesions, yet they are also malleable so that the accuracy of the bypass is lesion-dependent.
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Affiliation(s)
- Ryan W. Benson
- Department of Biology, Northeastern University, Boston, Massachusetts,
United States of America
| | - Matthew D. Norton
- Department of Biology, Northeastern University, Boston, Massachusetts,
United States of America
| | - Ida Lin
- Department of Biology, Northeastern University, Boston, Massachusetts,
United States of America
| | - William S. Du Comb
- Department of Biology, Northeastern University, Boston, Massachusetts,
United States of America
| | - Veronica G. Godoy
- Department of Biology, Northeastern University, Boston, Massachusetts,
United States of America
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4
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Alice AF, Pérez-Martínez G, Sánchez-Rivas C. Phosphoenolpyruvate phosphotransferase system and N-acetylglucosamine metabolism in Bacillus sphaericus. MICROBIOLOGY (READING, ENGLAND) 2003; 149:1687-1698. [PMID: 12855720 DOI: 10.1099/mic.0.26231-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacillus sphaericus, a bacterium of biotechnological interest due to its ability to produce mosquitocidal toxins, is unable to use sugars as carbon source. However, ptsHI genes encoding HPr and EI proteins belonging to a PTS were cloned, sequenced and characterized. Both HPr and EI proteins were fully functional for phosphoenolpyruvate-dependent transphosphorylation in complementation assays using extracts from Staphylococcus aureus mutants for one of these proteins. HPr(His(6)) was purified from wild-type and a Ser46/Gln mutant of B. sphaericus, and used for in vitro phosphorylation experiments using extracts from either B. sphaericus or Bacillus subtilis as kinase source. The results showed that both phosphorylated forms, P-Ser46-HPr and P-His15-HPr, could be obtained. The findings also proved indirectly the existence of an HPr kinase activity in B. sphaericus. The genetic structure of these ptsHI genes has some unusual features, as they are co-transcribed with genes encoding metabolic enzymes related to N-acetylglucosamine (GlcNAc) catabolism (nagA, nagB and an undetermined orf2). In fact, this bacterium was able to utilize this amino sugar as carbon and energy source, but a ptsH null mutant had lost this characteristic. Investigation of GlcNAc uptake and streptozotocin inhibition in both a wild-type and a ptsH null mutant strain led to the proposal that GlcNAc is transported and phosphorylated by an EII(Nag) element of the PTS, as yet uncharacterized. In addition, GlcNAc-6-phosphate deacetylase and GlcN-6-phosphate deaminase activities were determined; both were induced in the presence of GlcNAc. These results, together with the authors' recent findings of the presence of a phosphofructokinase activity, are strongly indicative of a glycolytic pathway in B. sphaericus. They also open new possibilities for genetic improvements in industrial applications.
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Affiliation(s)
- Alejandro F Alice
- Laboratorio de Microbiología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (1428), Argentina
| | - Gaspar Pérez-Martínez
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Paterna, Valencia, Spain
| | - Carmen Sánchez-Rivas
- Laboratorio de Microbiología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (1428), Argentina
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Riemann L, Azam F. Widespread N-acetyl-D-glucosamine uptake among pelagic marine bacteria and its ecological implications. Appl Environ Microbiol 2002; 68:5554-62. [PMID: 12406749 PMCID: PMC129920 DOI: 10.1128/aem.68.11.5554-5562.2002] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dissolved free and combined N-acetyl-D-glucosamine (NAG) is among the largest pools of amino sugars in the ocean. NAG is a main structural component in chitin and a substantial constituent of bacterial peptidoglycan and lipopolysaccharides. We studied the distribution and kinetics of NAG uptake by the phosphoenolpyruvate:NAG phosphotransferase systems (PTS) in marine bacterial isolates and natural bacterial assemblages in near-shore waters. Of 78 bacterial isolates examined, 60 took up 3H-NAG, while 18 showed no uptake. No systematic pattern in NAG uptake capability relative to phylogenetic affiliation was found, except that all isolates within Vibrionaceae took up NAG. Among 12 isolates, some showed large differences in the relationship between polymer hydrolysis (measured as chitobiase activity) and uptake of the NAG, the hydrolysis product. Pool turnover time and estimated maximum ambient concentration of dissolved NAG in samples off Scripps Pier (La Jolla, Calif.) were 5.9 +/- 3.0 days (n = 10) and 5.2 +/- 0.9 nM (n = 3), respectively. Carbohydrate competition experiments indicated that glucose, glucosamine, mannose, and fructose were taken up by the same system as NAG. Sensitivity to the antibiotic and NAG structural analog streptozotocin (STZ) was developed into a culture-independent approach, which demonstrated that approximately one-third of bacteria in natural marine assemblages that were synthesizing DNA took up NAG. Isolates possessing a NAG PTS system were found to be predominantly facultative anaerobes. These results suggest the hypothesis that a substantial fraction of bacteria in natural pelagic assemblages are facultative anaerobes. The adaptive value of fermentative metabolism in the pelagic environment is potentially significant, e.g., to bacteria colonizing microenvironments such as marine snow that may experience periodic O2-limitation.
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Affiliation(s)
- Lasse Riemann
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0202, USA.
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6
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Gauthier L, Thomas S, Gagnon G, Frenette M, Trahan L, Vadeboncoeur C. Positive selection for resistance to 2-deoxyglucose gives rise, in Streptococcus salivarius, to seven classes of pleiotropic mutants, including ptsH and ptsI missense mutants. Mol Microbiol 1994; 13:1101-9. [PMID: 7854124 DOI: 10.1111/j.1365-2958.1994.tb00501.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have used the toxic non-metabolizable glucose/mannose analogue 2-deoxyglucose to isolate a comprehensive collection of mutants of the phosphoenolpyruvate:sugar phosphotransferase system from Streptococcus salivarius. To increase the range of possible mutations, we isolated spontaneous mutants on different media containing 2-deoxyglucose and various metabolizable sugars, either lactose, melibiose, galactose or fructose. We found that the frequency at which 2-deoxyglucose-resistant mutants were isolated varied according to the growth substrate. The highest frequency was obtained with the combination galactose and 2-deoxyglucose and was 15-fold higher than the rate observed with the mixture melibiose and 2-deoxyglucose, the combination that gave the lowest frequency. By combining results from: (i) Western blot analysis of IIIMan, a specific component of the phosphoenolpyruvate:mannose phosphotransferase system in S. salivarius; (ii) rocket immunoelectrophoresis of HPr and EI, the two general energy-coupling proteins of the phosphotransferase system; and (iii) from gene sequencing, mutants could be assigned to seven classes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Gauthier
- Department of Biochemistry (Sciences), Université Laval, Québec, Canada
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7
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Parr TR, Saier MH. The bacterial phosphotransferase system as a potential vehicle for the entry of novel antibiotics. Res Microbiol 1992; 143:443-7. [PMID: 1448620 DOI: 10.1016/0923-2508(92)90089-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
During the past twenty-nine years, not a single class of antimicrobial agents has been discovered that has led to new approved human drugs. Despite a dramatic increase in the potency of existing classes, the need for new effective antimicrobial agents continues. The bacterial phosphotransferase system (PTS) offers the possibility of providing new opportunities for the discovery of important agents. This system offers a vehicle for entry into infecting bacteria and pathways for the initiation of metabolism of such agents. Antimicrobial agents which would use the PTS may be found which are active on both growing and sessile bacterial forms, and due to the lack of a eukaryotic PTS counterpart, such analogues may be expected to be non-toxic to the animal host.
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Affiliation(s)
- T R Parr
- Infectious Disease Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 45285-0428
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Romano AH, Saier MH, Harriott OT, Reizer J. Physiological studies on regulation of glycerol utilization by the phosphoenolpyruvate:sugar phosphotransferase system in Enterococcus faecalis. J Bacteriol 1990; 172:6741-8. [PMID: 2123855 PMCID: PMC210788 DOI: 10.1128/jb.172.12.6741-6748.1990] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In vitro studies with purified glycerol kinase from Enterococcus faecalis have established that this enzyme is activated by phosphorylation of a histidyl residue in the protein, catalyzed by the phosphoenolpyruvate-dependent phosphotransferase system (PTS), but the physiological significance of this observation is not known. In the present study, the regulation of glycerol uptake was examined in a wild-type strain of E. faecalis as well as in tight and leaky ptsI mutants, altered with respect to their levels of enzyme I of the PTS. Glycerol kinase was shown to be weakly repressible by lactose and strongly repressible by glucose in the wild-type strain. Greatly reduced levels of glycerol kinase activity were also observed in the ptsI mutants. Uptake of glycerol into intact wild-type and mutant cells paralleled the glycerol kinase activities in extracts. Glycerol uptake in the leaky ptsI mutant was hypersensitive to inhibition by low concentrations of 2-deoxyglucose or glucose even though the rates and extent of 2-deoxyglucose uptake were greatly reduced. These observations provide strong support for the involvement of reversible PTS-mediated phosphorylation of glycerol kinase in the regulation of glycerol uptake in response to the presence or absence of a sugar substrate of the PTS in the medium. Glucose and 2-deoxyglucose were shown to elicit rapid efflux of cytoplasmic [14C]lactate derived from [14C]glycerol. This phenomenon was distinct from the inhibition of glycerol uptake and was due to phosphorylation of the incoming sugar by cytoplasmic phosphoenolpyruvate. Lactate appeared to be generated by sequential dephosphorylation and reduction of cytoplasmic phosphoenolpyruvate present in high concentrations in resting cells. The relevance of these findings to regulatory phenomena in other bacteria is discussed.
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Affiliation(s)
- A H Romano
- Department of Biology, University of California, San Diego, La Jolla 92093
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9
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Jacobson GR, Poy F, Lengeler JW. Inhibition of Streptococcus mutans by the antibiotic streptozotocin: mechanisms of uptake and the selection of carbohydrate-negative mutants. Infect Immun 1990; 58:543-9. [PMID: 2137113 PMCID: PMC258491 DOI: 10.1128/iai.58.2.543-549.1990] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The antibiotic streptozotocin [2-deoxy-2-(3-methyl-3-nitrosoureido)-D-glucopyranoside], an analog of N-acetylglucosamine (NAG), has been shown to be useful for the selection of carbohydrate-negative and auxotrophic bacterial mutants. We have adapted this method for use with the oral pathogen Streptococcus mutans, a gram-positive, aerotolerant anaerobe that uses predominantly carbohydrates as carbon sources for growth. Streptozotocin selectively kills growing cells of S. mutans GS-5, and under appropriate conditions it can reduce the number of viable cells in actively growing cultures by a factor of 10(3) to 10(4). However, unlike in enteric bacteria, which take up this antibiotic by a single NAG-specific transport system, streptozotocin appears to be taken up in S. mutans by both a NAG-specific system and a relatively nonspecific system that is also involved in glucose, fructose, and mannose uptake. Combining streptozotocin selection and a screening procedure involving indicator plates containing triphenyl-tetrazolium chloride, we developed a general method for the isolation of carbohydrate-negative and auxotrophic mutants of S. mutans. A preliminary characterization of both pleiotropic and specific carbohydrate-negative mutants isolated by using this procedure is presented.
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Affiliation(s)
- G R Jacobson
- Department of Biology, Boston University, Massachusetts 02215
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Fram RJ, Mack SL, George M, Marinus MG. DNA repair mechanisms affecting cytotoxicity by streptozotocin in E. coli. Mutat Res 1989; 218:125-33. [PMID: 2475773 DOI: 10.1016/0921-8777(89)90018-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mechanisms underlying cytotoxicity by the monofunctional nitrosourea streptozotocin (STZ) were evaluated in DNA repair-deficient E. coli mutants. Strains not proficient in recombinational repair which lack either RecA protein or RecBC gene products were highly sensitive to STZ. In contrast, cells that constitutively synthesize RecA protein and cannot initiate SOS repair mechanisms because of uncleavable LexA repressor (recAo98 lexA3) were resistant to this drug compared to a lexA3 strain. Further, E. coli cells lacking both 3-methyladenine DNA glycosylases I (tag) and II (alkA) also were highly sensitive to STZ. DNA synthesis was most inhibited by STZ in recA and alkA tag E. coli mutants, but was suppressed less markedly in wild-type and recBC cells. DNA degradation was most extensive in recA E. coli after STZ treatment, while comparable in recBC, alkA tag, and wild-type cells. Although increased single-stranded DNA breaks were present after STZ treatment in recA and recBC mutants compared to the wild type, no significant increase in DNA single-stranded breaks was noted in alkA tag E. coli. Further, DNA breaks in recBC cells were repaired, while those present in recA cells were not. These findings establish the critical importance of both recombinational repair and 3-methyladenine DNA glycosylase in ameliorating cytotoxic effects and DNA damage caused by STZ in E. coli.
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Affiliation(s)
- R J Fram
- Department of Medicine, University of Massachusetts Medical School, Worcester 01655
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Abstract
Gene induction by the methylating agents streptozotocin (STZ), N-methyl-N-nitrosourea (MNU), and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was evaluated in E. coli fusion mutants. These mutants have fusions of the lac operon to genes induced by treatment with sublethal levels of alkylating agents and were previously selected from random insertions of the Mu-dl (Apr lac) phage by screening for induction of beta-galactosidase activity in the presence of methyl methanesulfonate or MNNG. The results demonstrate that STZ differs from MNNG and MNU in failing to induce aidC expression. Further, expression of aidC after exposure to MNU and MNNG occurs only in nonaerated cultures; aeration blocks the induction. Induction of aidD, alkA, aidB, and sfiA expression occurs with all 3 agents although at markedly lower concentrations of MNNG and STZ compared to MNU. alkA and to a lesser extent aidD mutants of E. coli strains were more sensitive to these agents, while no differences were evident between wild-type and aidB or aidC fusion mutants.
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Reizer J, Saier MH, Deutscher J, Grenier F, Thompson J, Hengstenberg W. The phosphoenolpyruvate:sugar phosphotransferase system in gram-positive bacteria: properties, mechanism, and regulation. Crit Rev Microbiol 1988; 15:297-338. [PMID: 3060316 DOI: 10.3109/10408418809104461] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This review consists of three major sections. The first and largest section reviews the protein constituents and known properties of the phosphotransferase systems present in well-studied Gram-positive bacteria. These bacteria include species of the following genera: (1) Staphylococcus, (2) Streptococcus, (3) Bacillus, (4) Lactobacillus, (5) Clostridium, (6) Arthrobacter, and (7) Brochothrix. The properties of the different systems are compared. The second major section deals with the regulation of carbohydrate uptake. There are four parts: (1) inhibition by intracellular sugar phosphates in Staphylococcus aureus, (2) PTS-mediated regulation of glycerol uptake in Bacillus subtilis, (3) competition for phospho-HPr in Streptococcus mutans, and (4) the possible involvement of protein kinases in the regulation of sugar uptake via the phosphotransferase system. The third section deals with the phenomenon of inducer expulsion. The first part is concerned with the physiological characterization of the phenomenon; then the consequences of unregulated uptake and expulsion, a futile cycle of energy expenditure, are considered. Finally, the biochemistry of the protein kinase and the protein phosphate phosphatase system, which appears to regulate sugar transport via the phosphotransferase system, is defined. The review, therefore, concentrates on the phosphotransferase system, its functions in carbohydrate transport and phosphorylation, the mechanisms of its regulation, and the mechanism by which it participates in the regulation of other physiological processes in the bacterial cell.
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Affiliation(s)
- J Reizer
- Department of Biology, University of California at San Diego, La Jolla
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Sprenger GA, Vogler A, Lengeler JW. Selection of auxotrophic and carbohydrate-negative mutants in penicillin-resistantKlebsiella pneumoniaeby nalidixic acid treatment. FEMS Microbiol Lett 1986. [DOI: 10.1111/j.1574-6968.1986.tb01812.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Styrvold OB, Falkenberg P, Landfald B, Eshoo MW, Bjørnsen T, Strøm AR. Selection, mapping, and characterization of osmoregulatory mutants of Escherichia coli blocked in the choline-glycine betaine pathway. J Bacteriol 1986; 165:856-63. [PMID: 3512526 PMCID: PMC214507 DOI: 10.1128/jb.165.3.856-863.1986] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Osmotically stressed Escherichia coli cells synthesize the osmoprotectant glycine betaine by oxidation of choline through glycine betaine aldehyde (choline----glycine betaine aldehyde----glycine betaine; B. Landfald and A.R. Strøm, J. Bacteriol. 165:849-855, 1986. Mutants blocked at the level of choline dehydrogenase were isolated by selection of strains which did not grow at elevated osmotic strength in the presence of choline but grew when supplemented with glycine betaine. A gene governing the choline dehydrogenase activity was named betA. Mapping by P1 transduction, F' complementation, and deletion mutagenesis showed the betA gene to be located at 7.5 min in the argF-codAB region of the chromosome. Mutants carrying deletions of this region also lacked glycine betaine aldehyde dehydrogenase activity and high-affinity uptake activity for choline; these deletions did not influence the activities of glycine betaine uptake or low-affinity choline uptake, both of which were osmotically regulated.
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Dunny G, Funk C, Adsit J. Direct stimulation of the transfer of antibiotic resistance by sex pheromones in Streptococcus faecalis. Plasmid 1981; 6:270-8. [PMID: 6796985 DOI: 10.1016/0147-619x(81)90035-4] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Lengeler J. Characterisation of mutants of Escherichia coli K12, selected by resistance to streptozotocin. MOLECULAR & GENERAL GENETICS : MGG 1980; 179:49-54. [PMID: 6450313 DOI: 10.1007/bf00268445] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
From cultures of sensitive bacteria, treated with the antibiotic streptozotocin, two classes of resistant mutants can be isolated: 1) mutants, resistant under all the conditions tested to even the highest doses of the antibiotic. These are either pleiotropic-defective, pts-mutants, or more frequently, mutants lacking a transport system (enzyme IINag-complex of the PEP-dependent phosphotransferase system) encoded by the gene nagE. This gene is inducible by N-acetyl-glucosamine and seems to be part of the nag operon. The transport system in question is responsible for the uptake of N-acetyl-glucosamine, of D-glucosamine and of streptozotocin; 2) conditional resistant mutants which are unable to energize or to synthesize the streptozotocin transport system under certain growth conditions but do have the transport activity under other conditions. These include a) mutants auxotrophic for amino acids, vitamins, or nucleotides, b) mutants negative or sensitive to carbohydrates in the medium, and c) mutants wth defects in energy metabolism such as PEP synthesis.
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