more information
Search within Results:

Select All    Deselect All
 |   | 
Details
   print
  Records Links
Author (up) Aertsen, A.; Michiels, C.W. file  url
openurl 
  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  
Permanent link to this record
 

 
Author (up) Kuhn, E. file  url
openurl 
  Title Toward understanding life under subzero conditions: the significance of exploring psychrophilic “cold-shock” proteins Type Journal Article
  Year 2012 Publication Astrobiology Abbreviated Journal Astrobiology  
  Volume 12 Issue 11 Pages 1078-1086  
  Keywords Adaptation, Physiological; Amino Acid Sequence; Cold Shock Proteins and Peptides--genetics, metabolism; Cold Temperature; Escherichia coli--enzymology, genetics, metabolism; Escherichia coli Proteins--genetics, metabolism; Freezing; Molecular Chaperones--genetics, metabolism; Molecular Sequence Data; Psychrobacter--enzymology, genetics, metabolism; RNA Helicases--genetics, metabolism  
  Abstract Understanding the behavior of proteins under freezing conditions is vital for detecting and locating extraterrestrial life in cold environments, such as those found on Mars and the icy moons of Jupiter and Saturn. This review highlights the importance of studying psychrophilic “cold-shock” proteins, a topic that has yet to be explored. A strategy for analyzing the psychrophilic RNA helicase protein CsdA (Psyc1082) from Psychrobacter arcticus 273-4 as a key protein for life under freezing temperatures is proposed. The experimental model presented here was developed based on previous data from investigations of Escherichia coli, P. arcticus 273-4, and RNA helicases. P. arcticus 273-4 is considered a model for life in freezing environments. It is capable of growing in temperatures as cold as -10 degrees C by using physiological strategies to survive not only in freezing temperatures but also under low-water-activity and limited-nutrient-availability conditions. The analyses of its genome, transcriptome, and proteome revealed specific adaptations that allow it to inhabit freezing environments by adopting a slow metabolic strategy rather than a cellular dormancy state. During growth at subzero temperatures, P. arcticus 273-4 genes related to energy metabolism and carbon substrate incorporation are downregulated, and genes for maintenance of membranes, cell walls, and nucleic acid motion are upregulated. At -6 degrees C, P. arcticus 273-4 does not upregulate the expression of either RNA or protein chaperones; however, it upregulates the expression of its cold-shock induced DEAD-box RNA helicase protein A (CsdA – Psyc1082). CsdA – Psyc1082 was investigated as a key helper protein for sustaining life in subzero conditions. Proving CsdA – Psyc1082 to be functional as a key protein for life under freezing temperatures may extend the known minimum growth temperature of a mesophilic cell and provide key information about the mechanisms that underlie cold-induced biological systems in icy worlds.  
  Call Number Serial 516  
Permanent link to this record
 

 
Author (up) Maciag-Dorszynska, M.; Ignatowska, M.; Janniere, L.; Wegrzyn, G.; Szalewska-Palasz, A. file  url
openurl 
  Title Mutations in central carbon metabolism genes suppress defects in nucleoid position and cell division of replication mutants in Escherichia coli Type Journal Article
  Year 2012 Publication Gene Abbreviated Journal Gene  
  Volume 503 Issue 1 Pages 31-35  
  Keywords Bacterial Structures--ultrastructure; Carbon--metabolism; Cell Division--genetics; DNA Replication--genetics; Escherichia coli--genetics, metabolism, ultrastructure; Escherichia coli Proteins--genetics, metabolism; Gene Deletion; Mutation  
  Abstract A genetic link of the carbon metabolism and DNA replication was recently reported for the representative of Gram-negative bacteria, Escherichia coli. Our studies showed that the viability of thermosensitive replication mutants at high temperature can be improved or fully recovered by deleting certain genes of central carbon metabolism (CCM). In order to improve our understanding of this phenomenon, in this study we analyzed the length and nucleoid distribution of suppressed thermosensitive replication mutants. The dysfunctions in the replication machinery generally lead to formation of elongated cells (termed filaments) that originate from an inhibition of cell division dependent on replication-stress, and to abnormal distribution and compaction of nucleoids. The results reported here provide evidence that deletion of the pta and ackA CCM genes significantly reduces observed cell length in the replication mutants dnaA46, dnaB8, dnaE486, dnaG(ts) and dnaN159. A weaker effect was shown in the tktB dnaE486 double mutant. The CCM enzyme dysfunction restored also the nucleoid shape and position in double mutants. The specificity of these effects was confirmed by overexpression of fully functional genes coding for relevant CCM enzymes, which caused the reversion to the initial filamentous and nucleoid phenotypes. These results indicate that CCM mutations can rescue (or reduce) the cell division defects resulting from various replication mutations. We thus suggest that the replication-metabolism connection may serve as a general mechanism affecting DNA duplication at various levels to adjust this process and the cell division to the status of cell physiology.  
  Call Number Serial 444  
Permanent link to this record
 

 
Author (up) Natale, P.; Pazos, M.; Vicente, M. file  url
openurl 
  Title The Escherichia coli divisome: born to divide Type Journal Article
  Year 2013 Publication Environmental Microbiology Abbreviated Journal Environ Microbiol  
  Volume 15 Issue 12 Pages 3169-3182  
  Keywords Bacterial Proteins--chemistry, metabolism; Cell Division; Cell Membrane--genetics, metabolism; Cytoskeletal Proteins--chemistry, metabolism; Escherichia coli--cytology, genetics, metabolism; Escherichia coli Proteins--genetics, metabolism; Peptidoglycan--biosynthesis  
  Abstract Septation in Escherichia coli involves complex molecular mechanisms that contribute to the accuracy of bacterial division. The proto-ring, a complex made up by the FtsZ, FtsA and ZipA proteins, forms at the beginning of the process and directs the assembly of the full divisome. Central to this complex is the FtsZ protein, a GTPase able to assemble into a ring-like structure that responds to several modulatory inputs including mechanisms to position the septum at midcell. The connection with the cell wall synthesising machinery stabilizes the constriction of the cytoplasmic membrane. Although a substantial amount of evidence supports this description, many details on how individual divisome elements are structured or how they function are subjected to controversial interpretations. We discuss these discrepancies arising from incomplete data and from technical difficulties imposed by the small size of bacteria. Future work, including more powerful imaging and reconstruction technologies, will help to clarify the missing details on the architecture and function of the bacterial division machinery.  
  Call Number Serial 814  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations: