Purification and characterization of two types of fumarase from Escherichia coli

Author: Ueda, Y.; Yumoto, N.; Tokushige, M.; Fukui, K.; Ohya-Nishiguchi, H. Description: Two distinct types of fumarase were purified to homogeneity from aerobically grown Escherichia coli W cells. The amino acid sequences of their NH2-terminals suggest that the two enzymes are the products of the fumA gene (FUMA) and fumC gene (FUMC), respectively. FUMA was separated from FUMC by chromatography on a Q-Sepharose column, and was further purified to homogeneity on Alkyl-Superose, Mono Q, and Superose 12 columns. FUMA is a dimer composed of identical subunits (Mr = 60,000). Although…

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Crystallographic studies of the catalytic and a second site in fumarase C from Escherichia coli

Author: Weaver, T.; Banaszak, L. Description: Fumarase C catalyzes the stereospecific interconversion of fumarate to l-malate as part of the metabolic citric acid or Kreb’s cycle. The recent three-dimensional structure of fumarase C from Escherichia coli has identified a binding site for anions which is generated by side chains from three of the four subunits within the tetramer. These same side chains are found in the three most highly conserved regions within the class II fumarase superfamily. The site was initially characterized by crystallographic studies through the binding of a…

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Survival of Escherichia coli in two sewage treatment plants using UV irradiation and chlorination for disinfection

Author: Anastasi, E. M.; Wohlsen, T. D.; Stratton, H. M.; Katouli, M. Description: We investigated the survival of Escherichia coli in two STPs utilising UV irradiation (STP-A) or chlorination (STP-B) for disinfection. In all, 370 E. coli strains isolated from raw influent sewage (IS), secondary treated effluent (STE) and effluent after the disinfection processes of both STPs were typed using a high resolution biochemical fingerprinting method and were grouped into common (C-) and single (S-) biochemical phenotypes (BPTs). In STP-A, 83 BPTs comprising 123 isolates were found in IS and…

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From acids to osmZ: multiple factors influence synthesis of the OmpF and OmpC porins in Escherichia coli

Author: Pratt, L.A.; Hsing, W.; Gibson, K.E.; Silhavy, T.J. Description: In Escherichia coli, levels of the two major outer membrane porin proteins, OmpF and OmpC, are regulated in response to a variety of environmental parameters, and numerous factors have been shown to influence porin synthesis. EnvZ and OmpR control porin-gene transcription in response to osmolarity, and the antisense RNA, MicF, influences ompF translation. In contrast to these characterized factors, some of the components reported to influence porin expression have only modest effects and/or act indirectly. For others, potential regulatory roles,…

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Inhibitory effect of Cinnamomum cassia oil on non-O157 Shiga toxin-producing Escherichia coli

Author: Sheng, L.; Zhu, M.-J. Description: Shiga toxin-producing Escherichia coli (STEC) have caused numerous foodborne outbreaks. Compared with the most well-known STEC E. coli O157:H7, importance of non-O157 STEC has been underestimated and they have gained far less attention till increasing outbreaks recently. Using natural plant materials as antimicrobial agents is a heated area. Therefore in this study, Cinnamomum cassia, a widely used spice in cuisine, was tested for its antibacterial efficacy on CDC “top six” non-O157 STECs including O26, O45, O103, O111, O121, O145. Gas chromatography-mass spectrometry analysis showed…

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Antibacterial properties of nine pure metals: a laboratory study using Staphylococcus aureus and Escherichia coli

Author: Yasuyuki, M.; Kunihiro, K.; Kurissery, S.; Kanavillil, N.; Sato, Y.; Kikuchi, Y. Description: Bacterial attachment and growth on material surfaces are considered to be the primary steps leading to the formation of biofilm. Biofilms in hospital and food processing settings can result in bacterial infection and food contamination, respectively. Prevention of bacterial attachment, therefore, is considered to be the best strategy for abating these menaces and therefore the development of antibacterial metals becomes important. In this study, nine pure metals, viz. titanium, cobalt, nickel, copper, zinc, zirconium, molybdenum, tin,…

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The Escherichia coli divisome: born to divide

Author: Natale, P.; Pazos, M.; Vicente, M. Description: 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…

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Effect of environmental factors and cell physiological state on Pulsed Electric Fields resistance and repair capacity of various strains of Escherichia coli

Author: Somolinos, M.; Garcia, D.; Manas, P.; Condon, S.; Pagan, R. Description: The aim was to determine the resistance variation of four strains of Escherichia coli to Pulsed Electric Fields (PEF), the role of the sigma factor RpoS in PEF resistance, as well as the influence of several environmental factors and the cell physiological state on the PEF resistance and repair capacity. The rpoS null mutant, E. coli BJ4L1, exhibited decreased PEF resistance as compared with its wild-type parent, BJ4. W3110 and O157:H7 were the most PEF-resistant strains: whereas 2…

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Evolution of Escherichia coli for growth at high temperatures

Author: Rudolph, B.; Gebendorfer, K.M.; Buchner, J.; Winter, J. Description: Evolution depends on the acquisition of genomic mutations that increase cellular fitness. Here, we evolved Escherichia coli MG1655 cells to grow at extreme temperatures. We obtained a maximum growth temperature of 48.5 degrees C, which was not increased further upon continuous cultivation at this temperature for >600 generations. Despite a permanently induced heat shock response in thermoresistant cells, only exquisitely high GroEL/GroES levels are essential for growth at 48.5 degrees C. They depend on the presence of lysyl-tRNA-synthetase, LysU, because…

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Pathogenic Escherichia coli

Author: Kaper, James B.; Nataro, James P.; Mobley, Harry L. Description: Few microorganisms are as versatile as Escherichia coli. An important member of the normal intestinal microflora of humans and other mammals, E. coli has also been widely exploited as a cloning host in recombinant DNA technology. But E. coli is more than just a laboratory workhorse or harmless intestinal inhabitant; it can also be a highly versatile, and frequently deadly, pathogen. Several different E. coli strains cause diverse intestinal and extraintestinal diseases by means of virulence factors that affect…

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