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Author (up) Aertsen, A.; Michiels, C.W. file  url
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  Title SulA-dependent hypersensitivity to high pressure and hyperfilamentation after high-pressure treatment of Escherichia coli lon mutants Type Journal Article
  Year 2005 Publication Research in Microbiology Abbreviated Journal Res Microbiol  
  Volume 156 Issue 2 Pages 233-237  
  Keywords Colony Count, Microbial; Culture Media; Escherichia coli--genetics, growth & development; Escherichia coli Proteins--genetics, metabolism; Gene Expression Regulation, Bacterial; Hydrostatic Pressure; Mutation; Protease La--genetics; SOS Response (Genetics); Ultraviolet Rays  
  Abstract High-pressure treatment (>100 MPa) is known to induce several heat shock proteins as well as an SOS response in Escherichia coli. In the current work, we have investigated properties with respect to high-pressure treatment of mutants-deficient in Lon, a pressure-induced ATP-dependent protease that belongs to the heat shock regulon but that also has a link to the SOS regulon. We report that lon mutants show increased pressure sensitivity and exhibit hyperfilamentation during growth after high-pressure treatment. Both phenotypes could be entirely attributed to the action of the SOS protein SulA, a potent inhibitor of the cell division ring protein FtsZ and a specific target of the Lon protease, since they were suppressed by knock-out of SulA. Introduction of the lexA1 allele, which effectively blocks the entire SOS response, also suppressed the high pressure hypersensitivity of lon mutants, but not their UV hypersensitivity. These results indicate the existence of a SulA-dependent pathway of high-pressure-induced cell filamentation, and suggest involvement of the SOS response, and particularly of SulA, in high-pressure-mediated cell death in E. coli strains which are compromised in Lon function.  
  Call Number Serial 301  
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Author (up) Cabiscol, E.; Tamarit, J.; Ros, J. file  url
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  Title Oxidative stress in bacteria and protein damage by reactive oxygen species Type Journal Article
  Year 2000 Publication International Microbiology : the Official Journal of the Spanish Society for Microbiology Abbreviated Journal Int Microbiol  
  Volume 3 Issue 1 Pages 3-8  
  Keywords Adaptation, Physiological; Aerobiosis; Amino Acids/chemistry; Bacteria/genetics/*metabolism; Bacterial Proteins/genetics/*metabolism/*physiology; DNA Damage; DNA, Bacterial/genetics/metabolism; *DNA-Binding Proteins; *Escherichia coli Proteins; Free Radicals; Gene Expression Regulation, Bacterial; Heat-Shock Proteins/metabolism; Iron-Sulfur Proteins/metabolism; Lipid Peroxidation; Oxidation-Reduction; Oxidative Stress/*genetics/physiology; Peroxides/metabolism; Reactive Oxygen Species/*metabolism; Repressor Proteins/genetics/*physiology; *Trans-Activators; Transcription Factors/genetics/*physiology; Transcription, Genetic  
  Abstract The advent of O2 in the atmosphere was among the first major pollution events occurred on earth. The reaction between ferrous iron, very abundant in the reductive early atmosphere, and oxygen results in the formation of harmful superoxide and hydroxyl radicals, which affect all macromolecules (DNA, lipids and proteins). Living organisms have to build up mechanisms to protect themselves against oxidative stress, with enzymes such as catalase and superoxide dismutase, small proteins like thioredoxin and glutaredoxin, and molecules such as glutathione. Bacterial genetic responses to oxidative stress are controlled by two major transcriptional regulators (OxyR and SoxRS). This paper reviews major key points in the generation of reactive oxygen species in bacteria, defense mechanisms and genetic responses to oxidative stress. Special attention is paid to the oxidative damage to proteins.  
  Call Number Serial 181  
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Author (up) Ducey, T.F.; Jackson, L.; Orvis, J.; Dyer, D.W. file  url
doi  openurl
  Title Transcript analysis of nrrF, a Fur repressed sRNA of Neisseria gonorrhoeae Type Journal Article
  Year 2009 Publication Microbial Pathogenesis Abbreviated Journal Microb Pathog  
  Volume 46 Issue 3 Pages 166-170  
  Keywords Bacterial Proteins/*physiology; Base Sequence; Escherichia coli; Gene Expression Profiling; *Gene Expression Regulation, Bacterial; Models, Molecular; Molecular Sequence Data; Neisseria gonorrhoeae/*physiology; RNA, Bacterial/*genetics; RNA, Untranslated/*metabolism; Repressor Proteins/*physiology; Transcription Initiation Site  
  Abstract Like most microorganisms, Neisseria gonorrhoeae alters gene expression in response to iron availability. The ferric uptake regulator Fur has been shown to be involved in controlling this response, but the extent of this involvement remains unknown. It is known that in addition to working directly to repress gene expression, Fur may also work indirectly by controlling additional regulatory elements. Using in silico analysis, we identified a putative small RNA (sRNA) homolog of the meningococcal nrrF locus, and demonstrate that this sRNA is iron-repressible, suggesting that this is the gonococcal analog of the rhyB locus in Escherichia coli. Quantitative real-time RT-PCR analysis indicates that this transcript may also be temporally regulated. Transcript analysis identified the 5' start of the transcript, using a single reaction, fluorescent-based, primer extension assay. This protocol allows for the rapid identification of transcriptional start sites of RNA transcripts, and could be used for high-throughput transcript mapping.  
  Call Number Serial 417  
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Author (up) Goley, E.D.; Yeh, Y.-C.; Hong, S.-H.; Fero, M.J.; Abeliuk, E.; McAdams, H.H.; Shapiro, L. file  url
doi  openurl
  Title Assembly of the Caulobacter cell division machine Type Journal Article
  Year 2011 Publication Molecular Microbiology Abbreviated Journal Mol Microbiol  
  Volume 80 Issue 6 Pages 1680-1698  
  Keywords Bacterial Proteins/genetics/*metabolism; Caulobacter crescentus/*cytology/genetics/*metabolism; *Cell Division; Gene Expression Regulation, Bacterial; Peptidoglycan/metabolism  
  Abstract Cytokinesis in Gram-negative bacteria is mediated by a multiprotein machine (the divisome) that invaginates and remodels the inner membrane, peptidoglycan and outer membrane. Understanding the order of divisome assembly would inform models of the interactions among its components and their respective functions. We leveraged the ability to isolate synchronous populations of Caulobacter crescentus cells to investigate assembly of the divisome and place the arrival of each component into functional context. Additionally, we investigated the genetic dependence of localization among divisome proteins and the cell cycle regulation of their transcript and protein levels to gain insight into the control mechanisms underlying their assembly. Our results revealed a picture of divisome assembly with unprecedented temporal resolution. Specifically, we observed (i) initial establishment of the division site, (ii) recruitment of early FtsZ-binding proteins, (iii) arrival of proteins involved in peptidoglycan remodelling, (iv) arrival of FtsA, (v) assembly of core divisome components, (vi) initiation of envelope invagination, (vii) recruitment of polar markers and cytoplasmic compartmentalization and (viii) cell separation. Our analysis revealed differences in divisome assembly among Caulobacter and other bacteria that establish a framework for identifying aspects of bacterial cytokinesis that are widely conserved from those that are more variable.  
  Call Number Serial 185  
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Author (up) Hare, J.M.; Adhikari, S.; Lambert, K.V.; Hare, A.E.; Grice, A.N. file  url
openurl 
  Title The Acinetobacter regulatory UmuDAb protein cleaves in response to DNA damage with chimeric LexA/UmuD characteristics Type Journal Article
  Year 2012 Publication FEMS Microbiology Letters Abbreviated Journal FEMS Microbiol Lett  
  Volume 334 Issue 1 Pages 57-65  
  Keywords Acinetobacter--enzymology, genetics, radiation effects; Amino Acid Sequence; Bacterial Proteins--chemistry, genetics, metabolism; DNA Damage--radiation effects; DNA-Directed DNA Polymerase--chemistry, genetics, metabolism; Escherichia coli--chemistry, enzymology, genetics, radiation effects; Escherichia coli Proteins--chemistry, genetics, metabolism; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Protein Processing, Post-Translational; Rec A Recombinases--genetics, metabolism; Sequence Alignment; Serine Endopeptidases--chemistry, genetics, metabolism; Ultraviolet Rays  
  Abstract In the DNA damage response of most bacteria, UmuD forms part of the error-prone (UmuD'(2) )C polymerase V and is activated for this function by self-cleavage after DNA damage. However, the umuD homolog (umuDAb) present throughout the Acinetobacter genus encodes an extra N-terminal region, and in Acinetobacter baylyi, regulates transcription of DNA damage-induced genes. UmuDAb expressed in cells was correspondingly larger (24 kDa) than the Escherichia coli UmuD (15 kDa). DNA damage from mitomycin C or UV exposure caused UmuDAb cleavage in both E. coli wild-type and DeltaumuD cells on a timescale resembling UmuD, but did not require UmuD. Like the self-cleaving serine proteases LexA and UmuD, UmuDAb required RecA for cleavage. This cleavage produced a UmuDAb' fragment of a size consistent with the predicted cleavage site of Ala83-Gly84. Site-directed mutations at Ala83 abolished cleavage, as did mutations at either the Ser119 or Lys156 predicted enzymatic residues. Co-expression of the cleavage site mutant and an enzymatic mutant did not allow cleavage, demonstrating a strictly intramolecular mechanism of cleavage that more closely resembles the LexA-type repressors than UmuD. These data show that UmuDAb undergoes a post-translational, LexA-like cleavage event after DNA damage, possibly to achieve its regulatory action.  
  Call Number Serial 491  
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