scholarly journals THE ROLE OF OPSONINS IN NON-SPECIFIC IMMUNITY

1960 ◽  
Vol 111 (1) ◽  
pp. 137-144 ◽  
Author(s):  
Derrick Rowley
Keyword(s):  
Normal Serum ◽  
Phagocytic Cells ◽  
E Coli ◽  
Specific Immunity ◽  
Viable Bacteria ◽  
Bacterial Lipopolysaccharides ◽  
Transport Of Bacteria

A study of the recoveries of radioactivity, and of viable bacteria following injection of P32-labelled E. coli into the mouse peritoneum, has indicated that the rapid decrease in viable bacteria which occurs is largely due to peritoneal events, and not to the transport of bacteria elsewhere. The serum from mice given lipopolysaccharides 48 hours previously, when used to pretreat bacteria before intraperitoneal injection, was found to stimulate phagocytosis to a greater extent than did pretreatment with normal serum. In addition, macrophages themselves were found to be affected by contact with lipopolysaccharides, either in vivo or in vitro in such a way as to promote their phagocytic abilities. It is suggested that the provocation of non-specific immunity by bacterial lipopolysaccharides involves two facets at least; firstly, an increase in the opsonic capacity of the serum, and secondly an increase in the inherent capacity of phagocytic cells to perform this function.

scholarly journals Arabidopsis Disulfide Reductase, Trx-h2, Functions as an RNA Chaperone under Cold Stress

2021 ◽  
Vol 11 (15) ◽  
pp. 6865
Author(s):  
Eun Seon Lee ◽  
Joung Hun Park ◽  
Seong Dong Wi ◽  
Ho Byoung Chae ◽  
Seol Ki Paeng ◽  
...  
Keyword(s):  
Cold Stress ◽  
Wild Type ◽  
Rna Chaperone ◽  
E Coli ◽  
Cold Sensitive ◽  
Thioredoxin H ◽  
Functional Rnas

The thioredoxin-h (Trx-h) family of Arabidopsis thaliana comprises cytosolic disulfide reductases. However, the physiological function of Trx-h2, which contains an additional 19 amino acids at its N-terminus, remains unclear. In this study, we investigated the molecular function of Trx-h2 both in vitro and in vivo and found that Arabidopsis Trx-h2 overexpression (Trx-h2OE) lines showed significantly longer roots than wild-type plants under cold stress. Therefore, we further investigated the role of Trx-h2 under cold stress. Our results revealed that Trx-h2 functions as an RNA chaperone by melting misfolded and non-functional RNAs, and by facilitating their correct folding into active forms with native conformation. We showed that Trx-h2 binds to and efficiently melts nucleic acids (ssDNA, dsDNA, and RNA), and facilitates the export of mRNAs from the nucleus to the cytoplasm under cold stress. Moreover, overexpression of Trx-h2 increased the survival rate of the cold-sensitive E. coli BX04 cells under low temperature. Thus, our data show that Trx-h2 performs function as an RNA chaperone under cold stress, thus increasing plant cold tolerance.

scholarly journals Regulatory Role of PlaR (YiaJ) for Plant Utilization in Escherichia coli K-12

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tomohiro Shimada ◽  
Yui Yokoyama ◽  
Takumi Anzai ◽  
Kaneyoshi Yamamoto ◽  
Akira Ishihama
Keyword(s):  
Escherichia Coli ◽  
Genetic System ◽  
Regulatory Role ◽  
E Coli ◽  
Warm Blooded Animal ◽  
Plant Utilization ◽  
K 12

AbstractOutside a warm-blooded animal host, the enterobacterium Escherichia coli K-12 is also able to grow and survive in stressful nature. The major organic substance in nature is plant, but the genetic system of E. coli how to utilize plant-derived materials as nutrients is poorly understood. Here we describe the set of regulatory targets for uncharacterized IclR-family transcription factor YiaJ on the E. coli genome, using gSELEX screening system. Among a total of 18 high-affinity binding targets of YiaJ, the major regulatory target was identified to be the yiaLMNOPQRS operon for utilization of ascorbate from fruits and galacturonate from plant pectin. The targets of YiaJ also include the genes involved in the utilization for other plant-derived materials as nutrients such as fructose, sorbitol, glycerol and fructoselysine. Detailed in vitro and in vivo analyses suggest that L-ascorbate and α-D-galacturonate are the effector ligands for regulation of YiaJ function. These findings altogether indicate that YiaJ plays a major regulatory role in expression of a set of the genes for the utilization of plant-derived materials as nutrients for survival. PlaR was also suggested to play protecting roles of E. coli under stressful environments in nature, including the formation of biofilm. We then propose renaming YiaJ to PlaR (regulator of plant utilization).

scholarly journals Role of interleukin-1 and tumour necrosis factor in leukocyte recruitment to acute dermal inflammation

1992 ◽  
Vol 1 (5) ◽  
pp. 347-353 ◽  
Author(s):  
Andrew C. Issekutz ◽  
Nancy Lopes ◽  
Thomas B. Issekutz
Keyword(s):  
Monoclonal Antibody ◽  
Umbilical Vein ◽  
Interleukin 1 ◽  
E Coli ◽  
Tnf Α ◽  
Lps Activation ◽  
Necrosis Factor

The cytokines IL-1 and TNF-α are involved in inflammation and their production is stimulated by various agents, especially endotoxin (LPS). Here, using the human IL-1 receptor antagonist (IL-1RA) and a new monoclonal antibody (mAb 7F11) to rabbit TNF, the role of endogenous IL-l and TNF production in acute (3h) leukocyte (PMNL) recruitment to dermal inflammation in rabbits has been studied. IL-1RA inhibited by 27% the PMNL accumulation in reactions induced by killed Escherichia coli (p < 0.05) but not by LPS. The monoclonal antibody to TNF inhibited by 27% and 38% (p < 0.002) the PMNL accumulation in LPS and E. coli reactions respectively, but a combination of the mAb with IL-1RA was not more effective. Treatment of human umbilical vein endothelium with LPS for 3 h activated endothelium to induce PMNL transendothelial migration in vitro, which was not inhibited by IL-1RA, antibody to TNF-α, IL-1 or to IL-8. In conclusion, TNF and IL-1 may partially mediate acute PMNL infiltration in vivo to LPS and Gram negative bacteria, but there is a major IL-1/TNF independent mechanism, at least in dermal inflammation, which may be due to direct LPS activation of the microvasculature or perhaps the generation of cytokines other than IL-1 and TNF.

scholarly journals Role of Escherichia coli Nitrogen Regulatory Genes in the Nitrogen Response of the Azotobacter vinelandiiNifL-NifA Complex

2001 ◽  
Vol 183 (10) ◽  
pp. 3076-3082 ◽  
Author(s):  
Francisca Reyes-Ramirez ◽  
Richard Little ◽  
Ray Dixon
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Nitrogen Control ◽  
Fixed Nitrogen ◽  
Nitrogen Response ◽  
E Coli ◽  
Nitrogen Excess

ABSTRACT The redox-sensing flavoprotein NifL inhibits the activity of the nitrogen fixation (nif)-specific transcriptional activator NifA in Azotobacter vinelandii in response to molecular oxygen and fixed nitrogen. Although the mechanism whereby the A. vinelandii NifL-NifA system responds to fixed nitrogen in vivo is unknown, the glnK gene, which encodes a PII-like signal transduction protein, has been implicated in nitrogen control. However, the precise function of A. vinelandii glnK in this response is difficult to establish because of the essential nature of this gene. We have shown previously that A. vinelandii NifL is able to respond to fixed nitrogen to control NifA activity when expressed inEscherichia coli. In this study, we investigated the role of the E. coli PII-like signal transduction proteins in nitrogen control of the A. vinelandii NifL-NifA regulatory system in vivo. In contrast to recent findings with Klebsiella pneumoniae NifL, our results indicate that neither the E. coli PII nor GlnK protein is required to relieve inhibition byA. vinelandii NifL under nitrogen-limiting conditions. Moreover, disruption of both the E. coli glnB andntrC genes resulted in a complete loss of nitrogen regulation of NifA activity by NifL. We observe that glnB ntrC and glnB glnK ntrC mutant strains accumulate high levels of intracellular 2-oxoglutarate under conditions of nitrogen excess. These findings are in accord with our recent in vitro observations (R. Little, F. Reyes-Ramirez, Y. Zhang, W. Van Heeswijk, and R. Dixon, EMBO J. 19:6041–6050, 2000) and suggest a model in which nitrogen control of the A. vinelandii NifL-NifA system is achieved through the response to the level of 2-oxoglutarate and an interaction with PII-like proteins under conditions of nitrogen excess.

scholarly journals THE ROLE OF PENICILLIN-INDUCED BACTERIAL VARIANTS IN EXPERIMENTAL PYELONEPHRITIS

1967 ◽  
Vol 125 (4) ◽  
pp. 607-618 ◽  
Author(s):  
Richard H. Winterbauer ◽  
Laura T. Gutman ◽  
Marvin Turck ◽  
Ralph J. Wedgwood ◽  
Robert G. Petersdorf
Keyword(s):  
Escherichia Coli ◽  
Renal Medulla ◽  
Round Cell ◽  
Histologic Response ◽  
E Coli ◽  
Round Cell Infiltration ◽  
Kidney Liver

1. After injection into the renal medulla of rats Escherichia coli 06 variants reverted rapidly in vivo in the absence of penicillin. These variants had previously been shown to be stable in vitro. 2. Variants failed to survive following intramedullary injection when animals were receiving penicillin. 3. Late reversion of variants also failed to occur in animals treated with penicillin for only 1 or 2 days. 4. Variants survived and reverted more readily when injected in the renal medulla, compared with liver and spleen. Classical bacteria injected into the kidney, liver, and spleen were recovered in approximately equal numbers. 5. The histologic response to nonreverting variants, medium not containing variants, and killed variants was similar and was characterized by a fibrotic reaction with moderate round cell infiltration. 6. In contrast, the histologic response to reverting variants and to classical E. coli was characterized by an intense, acute, polymorphonuclear leukocytosis typical of acute pyelonephritis.

scholarly journals The role of cytochrome P-450 in cholesterol biogenesis and catabolism

1972 ◽  
Vol 128 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Sandra D. Atkin ◽  
Eileen D. Palmer ◽  
P. D. English ◽  
B. Morgan ◽  
M. A. Cawthorne ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Carbon Disulphide ◽  
Normal Serum ◽  
Liver Cholesterol ◽  
Drug Metabolizing Enzyme ◽  
Metabolizing Enzyme ◽  
Cytochrome P 450

1. Adjuvant-induced arthritis in rats is accompanied by a loss of activity of the drug-metabolizing enzyme system and a decrease in hepatic cytochrome P-450. 2. Arthritic rats have normal serum and liver cholesterol concentrations. 3. The rate of biogenesis of cholesterol in vivo and in vitro from either [14C]acetate or [14C]mevalonate in arthritic rats was the same as or greater than that found in control rats. 4. Treatment of rats with carbon disulphide (1ml/kg) resulted in a loss of drug-metabolizing-enzyme activity and increased cholesterol biogenesis. 5. The activity of cholesterol 7α-hydroxylase in adjuvant-induced arthritic rats did not differ significantly from that in control rats. 6. Rats fed with cholestyramine had an elevated hepatic cholesterol 7α-hydroxylase activity, but neither the concentration of cytochrome P-450 nor the activity of the drug-hydroxylating enzyme, aminopyrine demethylase, was affected. 7. The relationships between drug hydroxylation and cholesterol metabolism are discussed.

scholarly journals Macrophage Class A Scavenger Receptor-Mediated Phagocytosis of Escherichia coli: Role of Cell Heterogeneity, Microbial Strain, and Culture Conditions In Vitro

2000 ◽  
Vol 68 (4) ◽  
pp. 1953-1963 ◽  
Author(s):  
Leanne Peiser ◽  
Peter J. Gough ◽  
Tatsuhiko Kodama ◽  
Siamon Gordon
Keyword(s):  
Escherichia Coli ◽  
Host Defense ◽  
Bacterial Strain ◽  
Chinese Hamster Ovary Cells ◽  
Culture Conditions ◽  
E Coli ◽  
Class A

ABSTRACT Macrophage class A scavenger receptors (SR-AI and SR-AII) contribute to host defense by binding polyanionic ligands such as lipopolysaccharide and lipoteichoic acid. SR-A knockout (SR-A−/−) mice are more susceptible to endotoxic shock and Listeria monocytogenes infection in vivo, possibly due to decreased clearance of lipopolysaccharide and microorganisms, respectively. We have used flow cytometry to analyze the role of SR-A and other scavenger-like receptors in phagocytosis of bacteria in vitro. Chinese hamster ovary cells stably transfected with human SR-A bound Escherichia coli and Staphylococcus aureus but ingested few organisms. Primary human monocyte-derived macrophages (Mφ) bound and ingested E. coli more efficiently, and this was partially but selectively blocked by the general SR inhibitor, poly(I). A specific and selective role for SR-A was shown, since bone marrow culture-derived Mφ from SR-A−/− mice ingested fewer E. coli organisms than did wild-type cells, while uptake of antibody-opsonized E. coli was unaffected. SR-A-dependent uptake of E. colivaried with the bacterial strain; ingestion of DH5α and K1 by SR-A−/− Mφ was reduced by 30 to 60% and 70 to 75%, respectively. Phagocytosis and endocytosis via SR-A were markedly down-modulated when Mφ were plated on serum-coated tissue culture plastic compared to bacteriologic plastic, where cell adhesion is mediated by SR-A and CR3, respectively. This paper demonstrates that SR-A can bind and ingest bacteria directly, consistent with a role in host defense in vivo, and highlights the importance of the source of the Mφ, bacterial strain, and culture conditions on receptor function in vitro.

scholarly journals Interaction of Bacillus subtilis CsaA with SecA and precursor proteins

2000 ◽  
Vol 348 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Jörg P. MÜLLER ◽  
Jörg OZEGOWSKI ◽  
Stefan VETTERMANN ◽  
Jelto SWAVING ◽  
Karel H. M. VAN WELY ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Specific Interaction ◽  
Membrane Vesicles ◽  
Protein Export ◽  
E Coli ◽  
Bacterium Bacillus Subtilis ◽  
Bacterium Bacillus

CsaA from the Gram-positive bacterium Bacillus subtilis has been identified previously as a suppressor of the growth and protein-export defect of Escherichia coli secA(Ts) mutants. CsaA has chaperone-like activities in vivo and in vitro. To examine the role of CsaA in protein export in B. subtilis, expression of the csaA gene was repressed. While export of most proteins remained unaffected, export of at least two proteins was significantly reduced upon CsaA depletion. CsaA co-immunoprecipitates and co-purifies with the SecA proteins of E. coli and B. subtilis, and binds the B. subtilis preprotein prePhoB. Purified CsaA stimulates the translocation of prePhoB into E. coli membrane vesicles bearing the B. subtilis translocase, whereas it interferes with the SecB-mediated translocation of proOmpA into membrane vesicles of E. coli. The specific interaction with the SecA translocation ATPase and preproteins suggests that CsaA acts as a chaperone that promotes the export of a subset of preproteins in B. subtilis.

scholarly journals Molecular Determinants for PspA-Mediated Repression of the AAA Transcriptional Activator PspF

2005 ◽  
Vol 187 (9) ◽  
pp. 3238-3248 ◽  
Author(s):  
Sarah Elderkin ◽  
Patricia Bordes ◽  
Susan Jones ◽  
Mathieu Rappas ◽  
Martin Buck
Keyword(s):  
Regulatory Protein ◽  
Membrane Integrity ◽  
Transcriptional Activator ◽  
Negative Regulator ◽  
E Coli ◽  
Molecular Determinants ◽  
Negative Effect

ABSTRACT The Escherichia coli phage shock protein system (pspABCDE operon and pspG gene) is induced by numerous stresses related to the membrane integrity state. Transcription of the psp genes requires the RNA polymerase containing the σ54 subunit and the AAA transcriptional activator PspF. PspF belongs to an atypical class of σ54 AAA activators in that it lacks an N-terminal regulatory domain and is instead negatively regulated by another regulatory protein, PspA. PspA therefore represses its own expression. The PspA protein is distributed between the cytoplasm and the inner membrane fraction. In addition to its transcriptional inhibitory role, PspA assists maintenance of the proton motive force and protein export. Several lines of in vitro evidence indicate that PspA-PspF interactions inhibit the ATPase activity of PspF, resulting in the inhibition of PspF-dependent gene expression. In this study, we characterize sequences within PspA and PspF crucial for the negative effect of PspA upon PspF. Using a protein fragmentation approach, we show that the integrity of the three putative N-terminal α-helical domains of PspA is crucial for the role of PspA as a negative regulator of PspF. A bacterial two-hybrid system allowed us to provide clear evidence for an interaction in E. coli between PspA and PspF in vivo, which strongly suggests that PspA-directed inhibition of PspF occurs via an inhibitory complex. Finally, we identify a single PspF residue that is a binding determinant for PspA.

scholarly journals Role of RpoS in the Virulence of Citrobacter rodentium

2008 ◽  
Vol 77 (1) ◽  
pp. 501-507 ◽  
Author(s):  
Tao Dong ◽  
Brian K. Coombes ◽  
Herb E. Schellhorn
Keyword(s):  
Pathogenicity Island ◽  
Competitive Growth ◽  
Citrobacter Rodentium ◽  
Wild Type ◽  
E Coli ◽  
Mouse Colon ◽  
Expression Of Genes

ABSTRACT Citrobacter rodentium is a mouse enteropathogen that is closely related to Escherichia coli and causes severe colonic hyperplasia and bloody diarrhea. C. rodentium infection requires expression of genes of the locus of enterocyte effacement (LEE) pathogenicity island, which simulates infection by enteropathogenic E. coli and enterohemorrhagic E. coli in the human intestine, providing an effective model for studying enteropathogenesis. In this study we investigated the role of RpoS, the stationary phase sigma factor, in virulence in C. rodentium. Sequence analysis showed that the rpoS gene is highly conserved in C. rodentium and E. coli, exhibiting 92% identity. RpoS was critical for survival under heat shock conditions and during exposure to H2O2 and positively regulated the expression of catalase KatE (HPII). The development of the RDAR (red dry and rough) morphotype, an important virulence trait in E. coli, was also mediated by RpoS in C. rodentium. Unlike E. coli, C. rodentium grew well in the mouse colon, and the wild-type strain colonized significantly better than rpoS mutants. However, a mutation in rpoS conferred a competitive growth advantage over the wild type both in vitro in Luria-Bertani medium and in vivo in the mouse colon. Survival analysis showed that the virulence of an rpoS mutant was attenuated. The expression of genes on the LEE pathogenicity island, which are essential for colonization and virulence, was reduced in the rpoS mutant. In conclusion, RpoS is important for the stress response and is required for full virulence in C. rodentium.

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