The antibacterial action of microcin J25: evidence for disruption of cytoplasmic membrane energization in Salmonella newport

Microcin J25 (MccJ25) is a cyclic peptide of 21 unmodified amino acid residues produced by a fecal strain of Escherichia coli. It has previously been shown that the antibiotic activity of this peptide is mainly directed to Enterobacteriaceae, including several pathogenic E. coli, Salmonella and Shigella strains. In this paper we show that MccJ25 acts on the cytoplasmic membrane of Salmonella newport cells producing alteration of membrane permeability, and the subsequent gradient dissipation, that initiate the inhibition of process, such as oxygen consumption. These results, taken together with our in vitro observations [Rintoul et al. (2000) Biochim. Biophys. Acta 1509, 65–72], strongly suggest that the disruption of the cytoplasmic membrane gradient is closely related to the bactericidal activity of MccJ25 in S. newport.Fil: Rintoul, Maria Regina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Fernandez, Beatriz Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Salomon, Raul Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Farias, Ricardo Norberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

A new hybrid bacteriocin, Ent35–MccV, displays antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria

Bacteriocins and microcins are ribosomally synthesized antimicrobial peptides that are usually active against phylogenetically related bacteria. Thus, bacteriocins are active against Gram-positive while microcins are active against Gram-negative bacteria. The narrow spectrum of action generally displayed by bacteriocins from lactic acid bacteria represents an important limitation for the application of these peptides as clinical drugs or as food biopreservatives. The present study describes the design and expression of a novel recombinant hybrid peptide combining enterocin CRL35 and microcin V named Ent35?MccV. The chimerical bacteriocin displayed antimicrobial activity against enterohemorrhagic Escherichia coli and Listeria monocytogenes clinical isolates, among other pathogenic bacteria. Therefore, Ent35?MccV may find important applications in food or pharmaceutical industries.Fil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Picariello, Gianluca. Consiglio Nazionale delle Ricerche. Istituto di Scienze dell’Alimentazione; ArgentinaFil: Sesma, Fernando Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; ArgentinaFil: Bellomio, Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucuman. Instituto Superior de Investigaciones Biologicas; Argentin

Conditioned mediums modulate expression of the RcsB-regulon genes in S. typhimurium

The Rcs is an unusual phosphorelay system composed of the inner membrane proteins RcsC and RcsD as sensors, and the response regulator RcsB. At the present, the signals that lead to activate the Rcs phosphorelay system remain unknown. Even though, a wide range of conditions have been described as Rcs system activation state. The growth at low temperature or on solid surface; the polymyxin B exposition; the DjlA overproduction, the rcsC11 constitutive mutation; mutations that affect cell envelope like tolB and pmrA, or rcsB overexpression are some examples of this activation states. Previously, we reported that the rcsB gene is transcribed from two promoters: i) PrcsDB located upstream of rcsD, and ii) PrcsB located within the rcsD coding region. The first promoter is induced during the exponential growth phase while the last one it does at lower levels in stationary phase. We also reported that the RcsB overproduction repressed the rcsD expression by directly binding to the PrcsDB promoter. The repression, resulting in a differential rate of rcsD and rcsB genes expression levels, was also observed using rcsC11 mutant or polymyxin B to induce the system. Under these conditions an increased level of RcsB was observed when the bacteria reach the stationary growth phase and the regulator began to be also transcribed from PrcsB. In addition, the PrcsB is physiologically required to maintain the repression on swarming behavior. The subject of the present work was to determine if an Rcs stimulation factor is excreted to the supernatant of tolB and pmrA mutant culture. This finding would allow us to identify the Rcs system signal. Here, the supernatant obtained from the above mutants cultures, as ?conditioned mediums?, was used to determine the reporter expression levels. The cps and flhDC operons were the reporter of the factor presence in the conditioned mediums. We demonstrated that the cps and flhDC operons were modulated under the growth on these mediums. As RcsB regulator is expressed exponential and stationary phase and the above reporters are exponentially controlled, we looking for reporter RcsB-depended gene that are transcribed in stationary phase like bapA gene. Here we report that asr is a new member of the RcsB regulon, which was reported as an stationary phase expressed gene. Additionally, we studied the expression modulation of asr, bap, cps and flhDC using conditioned medium harvested from both different growth phase in order to relate with expression of RcsB regulator. Under this condition we observed a growth phase-dependent expression mediated by RcsB. These results increase the Rcs system knowledge on regulon and ligand identification issues.Fil: Pescaretti, María de Las Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Lopez, Fabian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Delgado, Monica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaVI Congreso Argentina de Microbiología GeneralVilla Carlos PazArgentinaSociedad Argentina de Microbiología Genera

Identification of genes involved in the Salmonella typhimurium RcsCDB activation pathway

The Rcs system consists of the sensor protein RcsC, the cognate response regulator RcsB, and the histidin-containing phosphotransfer protein RcsD, which serve as an intermediary in the phosphoryl transfer from RcsC to RcsB. This system controls the biosynthesis of the colanic acid and flagella, and virulence genes. Although the real signal that leads to activation of this system is unknown, numerous membrane stress conditions are known to induce the Rcs system. In order to determine the system signal, we studied the effect of different compounds that affect the membrane on activation cascade system, through the expression of reporter genes. As several two-component systems respond to acetyl phosphate, we investigated the effect of ack and pta mutations in the activation of Rcs because they lead to its accumulation. Due to that in different conditions the glucose modulates the system, we analyzed the effect of mutations in genes involved in the pathway of glucose-6-phosphate required for the formation of enterobacterial common antigen (ECA). Our results contribute to understanding the relationship between membrane stresses with the metabolism of glucose to the activation of RcsCDB system.Fil: Pescaretti, María de Las Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Lopez, Fabian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Delgado, Monica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaXIV Congreso Latinoamericano de GenéticaViña del MarChileAsociación Latinoamericana de GenéticaSociedad de Genética de ChileAsociación Latinoamericana de Mutagénesis, Carcinogénesis y Teratogénesis AmbientalSociedad Argentina de Genétic

Co-expression and characterization of enterocin CRL35 and its mutant in Escherichia coli Rosetta

Even though many sequences and structures of bacteriocins from lactic acid bacteria have been fully characterized so far, little information is currently available about bacteriocins heterologously produced by Escherichia coli. For this purpose, the structural gene of enterocin CRL35, munA, was PCR-amplified using specific primers and cloned downstream PelB sequence in the pET22b (+) expression vector. E. coli Rosetta (DE3) pLysS was chosen as the host for production and enterocin was purified by an easy two-step protocol. The bacteriocin was correctly expressed with the expected intramolecular disulfide bond. Nevertheless, it was found that a variant of the enterocin, differing by 12 Da from the native polypeptide, was co-expressed by E. coli Rosetta in comparable amount. Indeed, the mutant bacteriocin contained two amino acid substitutions that were characterized by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) and HPLC-electrospray (ESI)-Q-TOF tandem mass spectrometry (MS/MS) sequencing. This is the first report regarding the production of mutants of pediocin-like bacteriocins in the E. coli expression system.Fil: Masias, Ruth Emilse. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Picariello, Gianluca. Consiglio Nazionale delle Ricerche (CNR). Istituto di Scienze dell’Alimentazione; ItaliaFil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Chalon, Miriam Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Sesma, Fernando Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Centro de Referencia Para Lactobacilos (i); ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Saavedra, Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Centro de Referencia Para Lactobacilos (i); Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Minahk, Carlos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; Argentin

The structure and biological aspects of peptide antibiotic microcin J25

Microcin J25 (MccJ25) is a plasmid-encoded peptide of 21 L-amino acids (G1-G-A-G-H5-V-P-E-Y-F10-V-G- I-G-T15-P-I-S-F-Y20-G), excreted to the medium by an Escherichia coli strain. MccJ25 is active on Gram-negative bacteria related to the producer strain, including some pathogenic strains. The four-plasmid genes mcjABCD, are involved in MccJ25 production: mcjA encodes a 58-residue precursor, mcjB and mcjC codify two processing enzymes required for the in vivo synthesis of the mature peptide and mcjD encodes the immunity protein (McjD), a member of the super family of ABC transporters. Immunity is mediated by active efflux of the peptide, keeping its intracellular concentration below a critical level. YojI, a chromosomal protein with ATP-binding-cassette-type exporter homology, is also able to export MccJ25. The E. coli outer membrane protein, TolC, is necessary for MccJ25 secretion mediated by either McjD or YojI. The uptake of MccJ25 is dependent on the outer-membrane receptor FhuA and the four inner-membrane proteins TonB, ExbD, ExbB and SbmA. At least two mechanisms described the action of MccJ25 on the target cells: (1) inhibition of the RNA-polymerase (RNAP) activity by obstructing the secondary channel, and consequently, preventing the access of the substrates to its active sites; and (2) operating on the cell membrane, MccJ25 disrupts the electric potential inhibiting the oxygen consumption in Salmonella enterica. MccJ25 also inhibits oxygen consumption and the respiratory chain enzymes in E. coli throughout the increasing of ROS concentration. Nevertheless the exact mechanism of this phenomenon must be elucidated. The MccJ25 exhibits a prolonged antimicrobial activity in a mouse infection model, suggesting a noteworthy potential for therapeutic uses.Fil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Microcin J25 membrane interaction: Selectivity toward gel phase

The interaction of the tryptophan-containing variant of microcin J25, MccJ25 I13W, with phosphatidylcholine membranes was studied by fluorescence spectroscopy techniques. The peptide was able to interact with dimiristoylphophatidylcholine and dipalmitoylphosphatidylcholine liposomes only when the membranes were in gel phase, as was demonstrated by the blue shift of the intrinsic fluorescence of MccJ25 I13W. The binding isotherm showed a cooperative partition of the peptide toward the membrane and the binding constant increased as the temperature decreased and the order parameter increased. No interaction with liquid crystalline membranes was observed. Studies of dynamic quenching of the fluorescence indicated that the peptide penetrated the lipid bilayer and was located primarily in the interfacial region. Our results suggest that MccJ25 I13W interacts with gel phase phospholipids and increases both its own affinity for the bilayer and the membrane permeability of small ions. © 2011 Elsevier B.V. All rights reserved.Fil: Dupuy, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

The antimicrobial peptide microcin J25 stabilizes the gel phase of bacterial model membranes

The bacterial membrane interaction of the antimicrobial peptide microcin J25 was studied with the probe-free techniques Langmuir monolayers and infrared spectroscopy. Membrane model systems composed by phosphatidylethanolamine:phosphatidylglycerol 7:3, which mimic the cytoplasmic membrane of Gram negative bacteria, were used in both monolayer and bilayer approaches. The peptide reduced the transition surface pressure of the expanded-to-condensed lipid monolayer states, as well as increased the gel-to-liquid crystalline transition temperature in bilayers, indicating a stabilization of membrane ordered state. In addition, a reduction of the surface pressure at which condensed domains appeared was observed upon mixed monolayers compression after microcin J25 adsorption. The results indicate a favorable interaction of microcin J25 with bacterial membrane model systems. Also, the effects on the ordered phases stabilization are discussed in terms of the biological effects observed in membranes of sensitive cells.Fil: Rintoul, Maria Regina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Dupuy, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; Argentin

Effect of Enterocin CRL35 on Listeria monocytogenes cell membrane

The antimicrobial peptide Enterocin CRL35, a class II bacteriocin, produces at high concentrations (8 μg ml-1) localized holes in the wall and cellular membrane of Listeria monocytogenes, reflected in the efflux of macromolecules such as proteins and other ultraviolet-absorbing materials. At lower concentrations (0.5 μg ml-1), neither ultra structural changes nor macromolecules efflux were observed, however potassium and phosphate ions were released, dissipating the proton motive force. As a result the bacteria were killed.Fil: Minahk, Carlos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Sesma, Fernando Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Glyceraldehyde-3-phosphate dehydrogenase tetramer dissociation and amyloid fibril formation induced by negatively charged membranes

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme related with Huntington's, Parkinson's and Alzheimer's diseases. The ability of negatively charged membranes to induce a rapid formation of GAPDH amyloid fibrils has been demonstrated, but the mechanisms by which GAPDH reaches the fibrillar state remains unclear. In this report, we describe the structural changes undergone by GAPDH at physiological pH and temperature conditions right from its interaction with acidic membranes until the amyloid fibril is formed. According to our results, the GAPDH-membrane binding induces a β-structuring process along with a loss of quaternary structure in the enzyme. In this way, experimental evidences on the initial steps of GAPDH amyloid fibrils formation pathway are provided.Fil: Cortez, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Avila, Cesar Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Torres Bugeau, Clarisa Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Farias, Ricardo Norberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Chehin, Rosana Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin