scholarly journals Cold Shock Exoribonuclease R (VacB) Is Involved in Aeromonas hydrophila Pathogenesis

2008 ◽  
Vol 190 (10) ◽  
pp. 3467-3474 ◽  
Author(s):  
Tatiana E. Erova ◽  
Valeri G. Kosykh ◽  
Amin A. Fadl ◽  
Jian Sha ◽  
Amy J. Horneman ◽  
...  
Keyword(s):  
Low Temperature ◽  
Aeromonas Hydrophila ◽  
Cold Shock ◽  
Shigella Flexneri ◽  
Cold Shock Protein ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Rnase R ◽  
Lethal Doses

ABSTRACT In this study, we cloned and sequenced a virulence-associated gene (vacB) from a clinical isolate SSU of Aeromonas hydrophila. We identified this gene based on our recently annotated genome sequence of the environmental isolate ATCC 7966T of A. hydrophila and the vacB gene of Shigella flexneri. The A. hydrophila VacB protein contained 798 amino acid residues, had a molecular mass of 90.5 kDa, and exhibited an exoribonuclease (RNase R) activity. The RNase R of A. hydrophila was a cold-shock protein and was required for bacterial growth at low temperature. The vacB isogenic mutant, which we developed by homologous recombination using marker exchange mutagenesis, was unable to grow at 4°C. In contrast, the wild-type (WT) A. hydrophila exhibited significant growth at this low temperature. Importantly, the vacB mutant was not defective in growth at 37°C. The vacB mutant also exhibited reduced motility, and these growth and motility phenotype defects were restored after complementation of the vacB mutant. The A. hydrophila RNase R-lacking strain was found to be less virulent in a mouse lethality model (70% survival) when given by the intraperitoneal route at as two 50% lethal doses (LD50). On the other hand, the WT and complemented strains of A. hydrophila caused 80 to 90% of the mice to succumb to infection at the same LD50 dose. Overall, this is the first report demonstrating the role of RNase R in modulating the expression of A. hydrophila virulence.

scholarly journals Role of the Cold-Box Region in the 5′ Untranslated Region of the cspA mRNA in Its Transient Expression at Low Temperature in Escherichia coli

1998 ◽  
Vol 180 (1) ◽  
pp. 90-95 ◽  
Author(s):  
Li Fang ◽  
Yan Hou ◽  
Masayori Inouye
Keyword(s):  
Escherichia Coli ◽  
Low Temperature ◽  
Untranslated Region ◽  
Cold Shock ◽  
Wild Type ◽  
Mrna Stabilization ◽  
High Level ◽  
Cold Box ◽  
In Cells

ABSTRACT Upon temperature downshift, a group of proteins called cold shock proteins, such as CspA, CspB, and CsdA, are transiently induced inEscherichia coli. However, when the 5′ untranslated region (5′ UTR) of cspA mRNA is overproduced at low temperature, the expression of cold shock genes is prolonged or derepressed. It has been proposed that this effect is due to highly conserved 11-base sequences designated the “cold box” existing in the 5′ UTRs ofcspA, cspB, and csdA. Here, we demonstrate that the overproduction of the 5′ UTR of not onlycspA but also cspB and csdA mRNAs causes derepression of all three genes at the same time. Conversely, when the cold-box region was deleted from the cspA 5′ UTR its derepression function was abolished. The amount of mRNA from the chromosomal cspA gene was much higher in cells overproducing the wild-type 5′ UTR by means of a plasmid than it was in cells overproducing the cold-box-deleted 5′ UTR. The stability of the chromosomal cspA mRNA in cells overproducing the wild-type 5′ UTR was almost identical to that in cells overproducing the cold-box-deleted 5′ UTR. Therefore, the derepression ofcspA caused by overproduction of 5′ UTR at the end of the acclimation phase occurs at the level of transcription but not by mRNA stabilization, indicating that the cold-box region plays a negative role in cspA transcription in cold shock-adapted cells. The role of the cold-box region was further confirmed with acspA mutant strain containing a cold-box-deletedcspA gene integrated into the chromosome, which showed a high level of constitutive production of CspA but not CspB during exponential growth at low temperature.

scholarly journals Two-Component-System Histidine Kinases Involved in Growth of Listeria monocytogenes EGD-e at Low Temperatures

2015 ◽  
Vol 81 (12) ◽  
pp. 3994-4004 ◽  
Author(s):  
Anna Pöntinen ◽  
Annukka Markkula ◽  
Miia Lindström ◽  
Hannu Korkeala
Keyword(s):  
Low Temperature ◽  
Histidine Kinase ◽  
Cold Shock ◽  
Wild Type ◽  
Histidine Kinases ◽  
Content Type ◽  
Expression Levels ◽  
Two Component ◽  
Cold Sensitive

ABSTRACTTwo-component systems (TCSs) aid bacteria in adapting to a wide variety of stress conditions. While the role of TCS response regulators in the cold tolerance of the psychrotrophic foodborne pathogenListeria monocytogeneshas been demonstrated previously, no comprehensive studies showing the role of TCS histidine kinases ofL. monocytogenesat low temperature have been performed. We compared the expression levels of each histidine kinase-encoding gene ofL. monocytogenesEGD-e in logarithmic growth phase at 3°C and 37°C, as well as the expression levels 30 min, 3 h, and 7 h after cold shock at 5°C and preceding cold shock (at 37°C). We constructed a deletion mutation in each TCS histidine kinase gene, monitored the growth of the EGD-e wild-type and mutant strains at 3°C and 37°C, and measured the minimum growth temperature of each strain. Two genes,yycGandlisK, proved significant in regard to induced relative expression levels under cold conditions and cold-sensitive mutant phenotypes. Moreover, the ΔresEmutant showed a lower growth rate than that of wild-type EGD-e at 3°C. Eleven other genes showed upregulated gene expression but revealed no cold-sensitive phenotypes. The results show that the histidine kinases encoded byyycGandlisKare important for the growth and adaptation ofL. monocytogenesEGD-e at low temperature.

scholarly journals Cold Shock Proteins of Lactococcus lactis MG1363 Are Involved in Cryoprotection and in the Production of Cold-Induced Proteins

2001 ◽  
Vol 67 (11) ◽  
pp. 5171-5178 ◽  
Author(s):  
Jeroen A. Wouters ◽  
Hélène Frenkiel ◽  
Willem M. de Vos ◽  
Oscar P. Kuipers ◽  
Tjakko Abee
Keyword(s):  
Low Temperature ◽  
Lactococcus Lactis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Cold Shock ◽  
Transcriptional Level ◽  
Wild Type ◽  
Cold Shock Proteins ◽  
Shock Proteins ◽  
Induced Proteins

ABSTRACT Members of the group of 7-kDa cold-shock proteins (CSPs) are the proteins with the highest level of induction upon cold shock in the lactic acid bacterium Lactococcus lactis MG1363. By using double-crossover recombination, two L. lactis strains were generated in which genes encoding CSPs are disrupted: L. lactis NZ9000ΔAB lacks the tandemly orientatedcspA and cspB genes, and NZ9000ΔABE lackscspA, cspB, and cspE. Both strains showed no differences in growth at normal and at low temperatures compared to that of the wild-type strain, L. lactis NZ9000. Two-dimensional gel electrophoresis showed that upon disruption of thecspAB genes, the production of remaining CspE at low temperature increased, and upon disruption of cspA, cspB, and cspE, the production of CspD at normal growth temperatures increased. Northern blot analysis showed that control is most likely at the transcriptional level. Furthermore, it was established by a proteomics approach that some (non-7-kDa) cold-induced proteins (CIPs) are not cold induced in the csp-lacking strains, among others the histon-like protein HslA and the signal transduction protein LlrC. This supports earlier observations (J. A. Wouters, M. Mailhes, F. M. Rombouts, W. M. De Vos, O. P. Kuipers, and T. Abee, Appl. Environ. Microbiol. 66:3756–3763, 2000). that the CSPs of L. lactis might be directly involved in the production of some CIPs upon low-temperature exposure. Remarkably, the adaptive response to freezing by prior exposure to 10°C was significantly reduced in strain NZ9000ΔABE but not in strain NZ9000ΔAB compared to results with wild-type strain NZ9000, indicating a notable involvement of CspE in cryoprotection.

Abstract 361: Creg1 Interacts With Sec8 to Promote Cell-cell Adhesion During Cardiomyogenesis

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Jie Liu ◽  
Yanmei Qi ◽  
Shu-Chan Hsu ◽  
Siavash Saadat ◽  
Saum Rahimi ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Es Cells ◽  
Embryonic Stem ◽  
Intercellular Junctions ◽  
Amino Acid Residues ◽  
Loss Of Function ◽  
Wild Type ◽  
Adhesion Sites ◽  
Cell Cell

Cellular repressor of E1A-stimulated genes 1 (CREG1) is a 24 kD glycoprotein essential for early embryonic development. Our immunofluorescence studies revealed that CREG1 is highly expressed at myocyte junctions in both embryonic and adult hearts. To explore it role in cardiomyogenesis, we employed gain- and loss-of-function analyses demonstrating that CREG1 is required for the differentiation of mouse embryonic stem (ES) cell into cohesive myocardium-like structures. Chimeric cultures of wild-type and CREG1 knockout ES cells expressing cardiac-specific reporters showed that the cardiomyogenic effect of CREG1 is cell autonomous. Furthermore, we identified a novel interaction between CREG1 and Sec8 of the exocyst complex, which tethers vesicles to the plasma membrane. Mutations of the amino acid residues D141 and P142 to alanine in CREG1 abolished its binding to Sec8. To address the role of the CREG1-Sec8 interaction in cardiomyogenesis, we rescued CREG1 knockout ES cells with wild-type and Sec8-binding mutant CREG1 and showed that CREG1 binding to Sec8 promotes cardiomyocyte differentiation and cohesion. Mechanistically, CREG1, Sec8 and N-cadherin all localize at cell-cell adhesion sites. CREG1 overexpression enhances the assembly of adherens and gap junctions. By contrast, its knockout inhibits the Sec8-N-cadherin interaction and induces their degradation. Finally, shRNA-mediated knockdown of Sec8 leads to cardiomyogenic defects similar to CREG1 knockout. These results suggest that the CREG1 binding to Sec8 enhances the assembly of intercellular junctions and promotes cardiomyogenesis.

scholarly journals Restart of Exponential Growth of Cold-Shocked Yersinia enterocolitica Occurs after Down-Regulation ofcspA1/A2 mRNA

2000 ◽  
Vol 182 (11) ◽  
pp. 3285-3288 ◽  
Author(s):  
Klaus Neuhaus ◽  
Sonja Rapposch ◽  
Kevin P. Francis ◽  
Siegfried Scherer
Keyword(s):  
Yersinia Enterocolitica ◽  
Exponential Growth ◽  
Cold Shock ◽  
Cold Shock Protein ◽  
Clear Correlation ◽  
Wild Type ◽  
Tandem Gene Duplication ◽  
Cellular Content ◽  
Shock Proteins ◽  
Mutant Cells

ABSTRACT The cellular content of major cold shock protein (MCSP) mRNA transcribed from the tandem gene duplication cspA1/A2 and growth of Yersinia enterocolitica were compared when exponentially growing cultures of this bacterium were cold shocked from 30 to 20, 15, 10, 5, or 0°C, respectively. A clear correlation between the time point when exponential growth resumes after cold shock and the degradation of cspA1/A2 mRNA was found. A polynucleotide phosphorylase-deficient mutant was unable to degradecspA1/A2 mRNA properly and showed a delay, as well as a lower rate, of growth after cold shock. For this mutant, a correlation between decreasing cspA1/A2 mRNA and restart of growth after cold shock was also observed. For both wild-type and mutant cells, no correlation of restart of growth with the cellular content of MCSPs was found. We suggest that, after synthesis of cold shock proteins and cold adaptation of the cells, MCSP mRNAs must be degraded; otherwise, they trap ribosomes, prevent translation of bulk mRNA, and thus inhibit growth of this bacterium at low temperatures.

scholarly journals Role of the Pilot Protein YscW in the Biogenesis of the YscC Secretin in Yersinia enterocolitica

2004 ◽  
Vol 186 (16) ◽  
pp. 5366-5375 ◽  
Author(s):  
Peter Burghout ◽  
Frank Beckers ◽  
Emmie de Wit ◽  
Ria van Boxtel ◽  
Guy R. Cornelis ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Yersinia Enterocolitica ◽  
Amino Acid Residues ◽  
Wild Type ◽  
C Terminus ◽  
Outer Membrane Lipoprotein ◽  
Protein Secretion System ◽  
Membrane Lipoprotein ◽  
Type Iii Protein Secretion

ABSTRACT The YscC secretin is a major component of the type III protein secretion system of Yersinia enterocolitica and forms an oligomeric structure in the outer membrane. In a mutant lacking the outer membrane lipoprotein YscW, secretion is strongly reduced, and it has been proposed that YscW plays a role in the biogenesis of the secretin. To study the interaction between the secretin and this putative pilot protein, YscC and YscW were produced in trans in a Y. enterocolitica strain lacking all other components of the secretion machinery. YscW expression increased the yield of oligomeric YscC and was required for its outer membrane localization, confirming the function of YscW as a pilot protein. Whereas the pilot-binding site of other members of the secretin family has been identified in the C terminus, a truncated YscC derivative lacking the C-terminal 96 amino acid residues was functional and stabilized by YscW. Pulse-chase experiments revealed that ∼30 min were required before YscC oligomerization was completed. In the absence of YscW, oligomerization was delayed and the yield of YscC oligomers was strongly reduced. An unlipidated form of the YscW protein was not functional, although it still interacted with the secretin and caused mislocalization of YscC even in the presence of wild-type YscW. Hence, YscW interacts with the unassembled YscC protein and facilitates efficient oligomerization, likely at the outer membrane.

scholarly journals Spatial, Temporal, and Functional Assessment of LC3-Dependent Autophagy inShigella flexneriDissemination

2018 ◽  
Vol 86 (8) ◽  
Author(s):  
Erin Weddle ◽  
Hervé Agaisse
Keyword(s):  
Colonic Mucosa ◽  
Defense Mechanism ◽  
Positive Impact ◽  
Shigella Flexneri ◽  
Wild Type ◽  
Content Type ◽  
Cell Defense ◽  
Membrane Protrusions ◽  
Cell Spread

ABSTRACTShigella flexneridisseminates within the colonic mucosa by displaying actin-based motility in the cytosol of epithelial cells. Motile bacteria form membrane protrusions that project into adjacent cells and resolve into double-membrane vacuoles (DMVs) from which the bacteria escape, thereby achieving cell-to-cell spread. During dissemination,S. flexneriis targeted by LC3-dependent autophagy, a host cell defense mechanism against intracellular pathogens. TheS. flexneritype III secretion system effector protein IcsB was initially proposed to counteract the recruitment of the LC3-dependent autophagy machinery to cytosolic bacteria. However, a recent study proposed that LC3 was recruited to bacteria in DMVs formed during cell-to-cell spread. To resolve the controversy and clarify the role of autophagy inS. flexneriinfection, we tracked dissemination using live confocal microscopy and determined the spatial and temporal recruitment of LC3 to bacteria. This approach demonstrated that (i) LC3 was exclusively recruited to wild-type oricsBbacteria located in DMVs and (ii) theicsBmutant was defective in cell-to-cell spread due to failure to escape LC3-positive as well as LC3-negative DMVs. Failure ofS. flexnerito escape DMVs correlated with late LC3 recruitment, suggesting that LC3 recruitment is the consequence and not the cause of DMV escape failure. Inhibition of autophagy had no positive impact on the spreading of wild-type oricsBmutant bacteria. Our results unambiguously demonstrate that IcsB is required for DMV escape during cell-to-cell spread, regardless of LC3 recruitment, and do not support the previously proposed notion that autophagy countersS. flexneridissemination.

Modulation of procaspase-7 self-activation by PEST amino acid residues of the N-terminal prodomain and intersubunit linker

2017 ◽  
Vol 95 (6) ◽  
pp. 634-643
Author(s):  
Juliano Alves ◽  
Miguel Garay-Malpartida ◽  
João M. Occhiucci ◽  
José E. Belizário
Keyword(s):  
Amino Acid ◽  
Large Subunit ◽  
Small Subunit ◽  
Cleavage Sites ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Caspase 7 ◽  
Caspase Family ◽  
The Impact

Procaspase-7 zymogen polypeptide is composed of a short prodomain, a large subunit (p20), and a small subunit (p10) connected to an intersubunit linker. Caspase-7 is activated by an initiator caspase-8 and -9, or by autocatalysis after specific cleavage at IQAD198↓S located at the intersubunit linker. Previously, we identified that PEST regions made of amino acid residues Pro (P), Glu (E), Asp (D), Ser (S), Thr (T), Asn (N), and Gln (Q) are conserved flanking amino acid residues in the cleavage sites within a prodomain and intersubunit linker of all caspase family members. Here we tested the impact of alanine substitution of PEST amino acid residues on procaspase-7 proteolytic self-activation directly in Escherichia coli. The p20 and p10 subunit cleavage were significantly delayed in double caspase-7 mutants in the prodomain (N18A/P26A) and intersubunit linker (S199A/P201A), compared with the wild-type caspase-7. The S199A/P201A mutants effectively inhibited the p10 small subunit cleavage. However, the mutations did not change the kinetic parameters (kcat/KM) and optimal tetrapeptide specificity (DEVD) of the purified mutant enzymes. The results suggest a role of PEST-amino acid residues in the molecular mechanism for prodomain and intersubunit cleavage and caspase-7 self-activation.

The role of the Shigella flexneri yihE gene in LPS synthesis and virulence

Microbiology ◽  
2004 ◽  
Vol 150 (4) ◽  
pp. 1079-1084 ◽  
Author(s):  
Bryn Edwards-Jones ◽  
Paul R. Langford ◽  
J. Simon Kroll ◽  
Jun Yu
Keyword(s):  
Gene Expression ◽  
Global Change ◽  
Unknown Function ◽  
Guinea Pigs ◽  
Antimicrobial Agents ◽  
Shigella Flexneri ◽  
Global Gene Expression ◽  
Wild Type ◽  
In Trans

Previously, the authors have shown that inactivation of Shigella flexneri yihE, a gene of unknown function upstream of dsbA, which encodes a periplasmic disulphide catalyst, results in a global change of gene expression. Among the severely down-regulated genes are galETKM, suggesting that the yihE mutant, Sh54, may inefficiently produce the UDP-glucose and UDP-galactose required for LPS synthesis. This paper demonstrates that LPS synthesis in Sh54 is impaired. As a result, Sh54 is unable to polymerize host cell actin, due to aberrant localization of IcsA, or to cause keratoconjunctivitis in guinea pigs. Furthermore, Sh54 is more sensitive to some antimicrobial agents, and exhibits epithelial cytotoxicity characteristic of neither wild-type nor dsbA mutants. Supplying galETK in trans restores LPS synthesis and corrects all the defects. Hence, it is clear that the Shigella yihE gene is important not only in regulating global gene expression, as shown previously, but also in virulence through LPS synthesis via regulating the expression of the galETK operon.

scholarly journals Braun Lipoprotein (Lpp) Contributes to Virulence of Yersiniae: Potential Role of Lpp in Inducing Bubonic and Pneumonic Plague

2008 ◽  
Vol 76 (4) ◽  
pp. 1390-1409 ◽  
Author(s):  
Jian Sha ◽  
Stacy L. Agar ◽  
Wallace B. Baze ◽  
Juan P. Olano ◽  
Amin A. Fadl ◽  
...  
Keyword(s):  
Acute Inflammation ◽  
Potential Role ◽  
Lethal Dose ◽  
Wild Type ◽  
Pneumonic Plague ◽  
Essentially Normal ◽  
Serovar Typhimurium ◽  
Highly Virulent ◽  
Lethal Doses

ABSTRACT Yersinia pestis evolved from Y. pseudotuberculosis to become the causative agent of bubonic and pneumonic plague. We identified a homolog of the Salmonella enterica serovar Typhimurium lipoprotein (lpp) gene in Yersinia species and prepared lpp gene deletion mutants of Y. pseudotuberculosis YPIII, Y. pestis KIM/D27 (pigmentation locus minus), and Y. pestis CO92 with reduced virulence. Mice injected via the intraperitoneal route with 5 × 107 CFU of the Δlpp KIM/D27 mutant survived a month, even though this would have constituted a lethal dose for the parental KIM/D27 strain. Subsequently, these Δlpp KIM/D27-injected mice were solidly protected against an intranasally administered, highly virulent Y. pestis CO92 strain when it was given as five 50% lethal doses (LD50). In a parallel study with the pneumonic plague mouse model, after 72 h postinfection, the lungs of animals infected with wild-type (WT) Y. pestis CO92 and given a subinhibitory dose of levofloxacin had acute inflammation, edema, and masses of bacteria, while the lung tissue appeared essentially normal in mice inoculated with the Δlpp mutant of CO92 and given the same dose of levofloxacin. Importantly, while WT Y. pestis CO92 could be detected in the bloodstreams and spleens of infected mice at 72 h postinfection, the Δlpp mutant of CO92 could not be detected in those organs. Furthermore, the levels of cytokines/chemokines detected in the sera were significantly lower in animals infected with the Δlpp mutant than in those infected with WT CO92. Additionally, the Δlpp mutant was more rapidly killed by macrophages than was the WT CO92 strain. These data provided evidence that the Δlpp mutants of yersiniae were significantly attenuated and could be useful tools in the development of new vaccines.

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