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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 03 May 2011, Vol.108(18), pp.7403-7
    Description: Eukaryotic PIN (PilT N-terminal) domain proteins are ribonucleases involved in quality control, metabolism and maturation of mRNA and rRNA. The majority of prokaryotic PIN-domain proteins are encoded by the abundant vapBC toxin--antitoxin loci and inhibit translation by an unknown mechanism. Here we show that enteric VapCs are site-specific endonucleases that cleave tRNA(fMet) in the anticodon stem-loop between nucleotides +38 and +39 in vivo and in vitro. Consistently, VapC inhibited translation in vivo and in vitro. Translation-reactions could be reactivated by the addition of VapB and extra charged tRNA(fMet). Similarly, ectopic production of tRNA(fMet) counteracted VapC in vivo. Thus, tRNA(fMet) is the only cellular target of VapC. Depletion of tRNA(fMet) by vapC induction was bacteriostatic and stimulated ectopic translation initiation at elongator codons. Moreover, addition of chloramphenicol to cells carrying vapBC induced VapC activity. Thus, by cleavage of tRNA(fMet), VapC simultaneously may regulate global cellular translation and reprogram translation initiation.
    Keywords: Bacterial Proteins -- Metabolism ; Endoribonucleases -- Metabolism ; Gene Expression Regulation, Bacterial -- Physiology ; Membrane Glycoproteins -- Metabolism ; RNA, Transfer, Met -- Metabolism ; Salmonella Typhimurium -- Enzymology ; Shigella Flexneri -- Enzymology
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    In: Nature, 2016, Vol.534(7605), p.41
    Keywords: Microbiology ; Antibiotics ; Microbial Drug Resistance;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 3
    In: Nature, 2013, Vol.503(7476), p.347
    ISSN: 0028-0836
    E-ISSN: 1476-4687
    Source: Nature Publishing Group
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  • 4
    Article
    Article
    Language: English
    In: Nature, 11/2013, Vol.503(7476), pp.347-349
    Description: [...]general proteases such as Clp are typically either essential for bacterial survival or are required for bacterial virulence. [...]if spontaneous S. aureus mutants arise that lack ClpP and are resistant to ADEPs, they will display greatly reduced virulence9. [...]will the breakthrough presented by...
    Keywords: Microbiology ; Proteins ; Bacteria ; Staphylococcus Infections ; Hypotheses ; Enzymes;
    ISSN: 0028-0836
    E-ISSN: 1476-4687
    Source: Nature Publishing Group (via CrossRef)
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  • 5
    Language: English
    In: Nature, June 2, 2016, Vol.534(7605), p.41(2)
    Description: In bacterial persistence, a small fraction of an antibiotic-sensitive cell population has switched to a slow-growing or dormant state, and is drug tolerant1,2. This differs from antibiotic resistance in that regrowth of a persistent population results in the same percentage of drug-sensitive cells as...
    Keywords: Microbial Drug Resistance – Research
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 6
    Language: English
    In: Journal of Bacteriology, Jan, 2012, Vol.194(1-2), p.292(11)
    Description: Bacterial cell division relies on the formation and contraction of the Z ring, coordinated and regulated by a dynamic protein complex called the divisome. The cell division factor ZapA interacts directly with FtsZ and thereby increases FtsZ protofilament association and Z-ring stability. Here, we investigated ZapB interaction with ZapA and its effect on Z-ring formation and FtsZ protofilament bundling. The combination of the ftsZ84 allele that encodes an FtsZ variant that polymerizes inefficiently with a zapB null mutant resulted in a synthetic defective phenotype. Overproduction of ZapA led to the formation of aberrant FtsZ helical structures and delocalization of ZapB. The N-terminal end of ZapB was essential for ZapB-ZapA interaction, and amino acid changes close to the N terminus of ZapB exhibited reduced interaction with ZapA. Sedimentation assays showed that ZapB interacts strongly with ZapA and reduces ZapA's interaction with FtsZ in vitro. The morphology of the structures formed by ZapA and ZapB together was similar to the cables formed by ZapB in the presence of Ca[Cl.sub.2], a known ZapB bundling agent. The in vivo and in vitro data support a model in which ZapA interacts strongly with ZapB and the ZapA-ZapB interaction is favored over ZapA-FtsZ. doi: 10.1128/JB.05821-11
    Keywords: Escherichia Coli
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Nature, Nov 21, 2013, Vol.503(7476), p.347(2)
    Keywords: Microbial Drug Resistance – Research
    ISSN: 0028-0836
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  • 8
    Language: English
    In: Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 05 November 2016, Vol.371(1707)
    Description: Bacteria form persisters, cells that are tolerant to multiple antibiotics and other types of environmental stress. Persister formation can be induced either stochastically in single cells of a growing bacterial ensemble, or by environmental stresses, such as nutrient starvation, in a subpopulation of cells. In many cases, the molecular mechanisms underlying persistence are still unknown. However, there is growing evidence that, in enterobacteria, both stochastically and environmentally induced persistence are controlled by the second messenger (p)ppGpp. For example, the 'alarmone' (p)ppGpp activates Lon, which, in turn, activates type II toxin-antitoxin (TA) modules to thereby induce persistence. Recently, it has been shown that a type I TA module, hokB/sokB, also can induce persistence. In this case, the underlying mechanism depends on the universally conserved GTPase Obg and, surprisingly, also (p)ppGpp. In the presence of (p)ppGpp, Obg stimulates hokB transcription and induces persistence. HokB toxin expression is under both negative and positive control: SokB antisense RNA inhibits hokB mRNA translation, while (p)ppGpp and Obg together stimulate hokB transcription. HokB is a small toxic membrane protein that, when produced in modest amounts, leads to membrane depolarization, cell stasis and persistence. By contrast, overexpression of HokB disrupts the membrane potential and kills the cell. These observations raise the question of how expression of HokB is regulated. Here, I propose a homoeostatic control mechanism that couples HokB expression to the membrane-bound RNase E that degrades and inactivates SokB antisense RNA.This article is part of the themed issue 'The new bacteriology'.
    Keywords: Hokb ; Rnase E ; Antitoxin ; Bacterial Persistence ; Membrane Homoeostasis ; Toxin ; Homeostasis ; Bacterial Toxins -- Genetics ; Cell Membrane -- Physiology ; Escherichia Coli -- Physiology ; Escherichia Coli Proteins -- Genetics
    ISSN: 09628436
    E-ISSN: 1471-2970
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  • 9
    Language: English
    In: Science (New York, N.Y.), 16 December 2016, Vol.354(6318)
    Description: Bacterial persister cells avoid antibiotic-induced death by entering a physiologically dormant state and are considered a major cause of antibiotic treatment failure and relapsing infections. Such dormant cells form stochastically, but also in response to environmental cues, by various pathways that are usually controlled by the second messenger (p)ppGpp. For example, toxin-antitoxin modules have been shown to play a major role in persister formation in many model systems. More generally, the diversity of molecular mechanisms driving persister formation is increasingly recognized as the cause of physiological heterogeneity that underlies collective multistress and multidrug tolerance of persister subpopulations. In this Review, we summarize the current state of the field and highlight recent findings, with a focus on the molecular basis of persister formation and heterogeneity.
    Keywords: Drug Resistance, Multiple, Bacterial ; Adaptation, Physiological -- Physiology ; Anti-Bacterial Agents -- Pharmacology ; Bacteria -- Drug Effects ; Bacterial Infections -- Microbiology ; Stress, Physiological -- Physiology
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 10
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 2011, Vol.108(32), pp.13206-13211
    Description: Bacteria form persisters, individual cells that are highly tolerant to different types of antibiotics. Persister cells are genetically identical to nontolerant kin but have entered a dormant state in which they are recalcitrant to the killing activity of the antibiotics. The molecular mechanisms underlying bacterial persistence are unknown. Here, we show that the ubiquitous Lon (Long Form Filament) protease and mRNA endonucleases (mRNases) encoded by toxin-antitoxin (TA) loci are required for persistence in Escherichia coli. Successive deletion of the 10 mRNase-encoding TA loci of E. coli progressively reduced the level of persisters, showing that persistence is a phenotype common to TA loci. In all cases tested, the antitoxins, which control the activities of the mRNases, are Lon substrates. Consistently, cells lacking lon generated a highly reduced level of persisters. Moreover, Lon overproduction dramatically increased the levels of persisters in wild-type cells but not in cells lacking the 10 mRNases. These results support a simple model according to which mRNases encoded by TA loci are activated in a small fraction of growing cells by Lon-mediated degradation of the antitoxins. Activation of the mRNases, in turn, inhibits global cellular translation, and thereby induces dormancy and persistence. Many pathogenic bacteria known to enter dormant states have a plethora of TA genes. Therefore, in the future, the discoveries described here may lead to a mechanistic understanding of the persistence phenomenon in pathogenic bacteria. ; p. 13206-13211.
    Keywords: Models ; Antibiotics ; Messenger Rna ; Antitoxins ; Proteinases ; Genes ; Bacteria ; Escherichia Coli ; Loci ; Phenotype ; Dormancy
    ISSN: 0027-8424
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