Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
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Growth, enterotoxin A (SEA) and thermonuclease (TNase) production of S. aureus (Strains CP 7 and FRI 722) was determined in media produced from the following heat or irradiation sterilized legumes: peas, black beans, mung beans, adzuki beans and soybeans. Media containing the five legumes alone or in combination with Brain Heart Infusion Broth (BHI) were tested. With the exception of heat-sterilized black beans and adzuki beans, S. aureus growth was excellent in all media with cell counts after 48 h (25 degrees C) exceeding 10(8) cfu/ml. In black beans and adzuki beans cell counts were 1-2 log-cycles lower. Enterotoxin A was produced in amounts of 33 to 72 ng/ml in BHI after 48 h. Almost no toxin was produced in the four different beans following heat or irradiation treatment; in peas the toxin concentration reached 14 to 15 ng/ml. In the medium prepared from irradiated soybeans and BHI the final toxin concentration was about the same as in BHI alone. In all the other media consisting of a combination of legumes with BHI toxin concentrations were three to four times higher than in BHI alone. Production of thermonuclease showed variation and did not always correlate with enterotoxin production.
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PMID:Production of enterotoxin A and thermonuclease by Staphylococcus aureus in legumes. 239 54

The fibrosarcoma IC9 is deficient in the expression of the major histocompatibility complex class I genes Kb, Kk, and Dk and expresses only the Db molecule. Because class I deficiency may enable tumor cells to escape the immune response by cytotoxic T lymphocytes, we investigated why the class I genes are not expressed. Expression of the silent class I genes could not be induced, but all known DNA-binding factors specific for class I genes could be detected in nuclear extracts of IC9 cells. After cloning of the silent Kb gene from the IC9 cells and subsequent transfection of this cloned Kb gene into LTK- and IC9 cells, normal Kb antigens were expressed on the cell surface of both cell lines. Digestion of the chromatin of IC9 cells with micrococcal nuclease and DNase I showed a decreased nuclease sensitivity of the silent class I genes in comparison with active genes and the absence of DNase I hypersensitive sites in the promoter region of the silent Dk gene. These findings demonstrate that class I expression is turned off by a cis-acting regulatory mechanism at the level of the chromatin structure.
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PMID:Major histocompatibility complex class I genes in murine fibrosarcoma IC9 are down regulated at the level of the chromatin structure. 250 38

Production of enterotoxin A (SEA), enterotoxin C (SEC), and thermonuclease (TNase) by Staphylococcus aureus was determined during growth in cooked egg-noodles at different temperatures (15-37 degrees C). Both SEA and SEC and TNase were detected when greater than or equal to 4.0 x 10(7) colony forming units (cfu)/g were present. The contents of SEA, SEC, and TNase in egg-noodles mainly increased at the end of the exponential growth phase. In contrast with SEA and SEC the production of TNase always continued till the end of each experiment. Recovery rates of SEA and TNase in cooked noodles were dependent on their amounts. High amounts (64 ng SEA/g; 1 unit TNase/g) were recovered at a rate of 93% (SEA) and 54% (TNase) respectively, whereas low concentrations (1 ng SEA/g; 0.004 units TNase/g) were recovered at a rate of only 45% (SEA) and 1.1% (TNase). TNase usually is produced at all conditions which allow growth of S. aureus. Evidence of TNase was proposed for screening for staphylococcal enterotoxins (SE) in foods. But sometimes foods contain no TNase but SE. For this reason the ELISA-test which is simple and sensitive should be used for determination of SE-production in foods.
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PMID:Production of enterotoxins and thermonuclease by Staphylococcus aureus in cooked egg-noodles. 327 95

Milk samples from 251 nursing mothers were screened for enterotoxigenic staphylococci. The incidence of staphylococci in milk samples was 71.3%. Two hundred and sixteen strains were isolated from 179 mothers. Eighty-six (39.8%) of the 216 strains were found to be toxigenic. Enterotoxin type A (SEA) predominated, with 41 strains (19.0%) elaborating it. Twenty-one strains (9.7%) produced enterotoxin B (SEB) while only eight (3.7%) produced enterotoxin C (SEC). Ten strains (4.6%) produced all three types. Enterotoxigenic strains usually produced coagulase, thermonuclease and alpha haemolysin. In this series breast-feeding alone was more common than combined breast and bottle feeding, especially among mothers less than 30 years old. The incidence of reported infantile diarrhoea decreased with increasing age of the mother. Of 16 babies with diarrhoea, 10 (62.5%) had mothers whose milk yielded staphylococci. Six of these were toxigenic. Although no direct relationship between enterotoxigenic staphylococci in the milk of nursing mothers and infantile diarrhoea could be demonstrated, these findings reveal a potential health risk to these infants.
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PMID:Frequency of isolation of enterotoxigenic staphylococci from milk of nursing mothers in Kaduna, Nigeria. 651 54

The ability of 309 staphylococcal isolates from household dogs to produce enterotoxin, coagulase, thermonuclease and hemolysin was investigated. A total of 52 (16.8%) isolates from 45 out of 150 dogs examined were enterotoxigenic when tested for enterotoxin types A, B and C. Based on sites sampled, 33 (20.5%) out of 161 isolates from the anterior nares were enterotoxigenic while from dorsal skins 19 (12.8%) out of 148 isolates were enterotoxigenic. Staphylococcal enterotoxin C(SEC) was predominantly produced as 21 (6.8%) isolates elaborated it and also accounted for 40.4% of all enterotoxins produced by isolates. Staphylococcal enterotoxins A(SEA) and B(SEB) were produced by 10 (3.2%) and 16 (5.2%) strains, respectively. Mixed enterotoxin types AB, AC and BC were produced by 1,3 and 1 strains, respectively. With human plasma, 17.1% of coagulase-positive and 15.0% of coagulase-negative strains were enterotoxigenic. However, using canine plasma, 19.1% and 6.9% of the coagulase-positive and negative isolates, respectively, were enterotoxigenic. The incidence of enterotoxigenicity was 16.9% amongst thermonuclease-positive isolates and 16.3% for thermonuclease-negative strains. Alpha hemolysin was predominantly produced by 180 (60.2%) isolates and 19.9% of these were enterotoxigenic. Beta hemolysin was produced by 36 (11.7%) isolates with 13.9% enterotoxigenic, while 87 (28.2%) exhibited gamma hemolytic pattern amongst which 11.5% were enterotoxigenic. Based on data provided on coagulation of human and canine plasmas and hemolytic patterns, it is concluded that a large proportion of canine isolates from this environment are not of canine biotypes, but are most probably human biotypes.
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PMID:Isolation of enterotoxigenic strains of staphylococci from dogs. 664 5

Saccharomyces cerevisiae general regulatory factor CP1 (encoded by the gene CEP1) is required for optimal chromosome segregation and methionine prototrophy. MET16-CYC1-lacZ reporter constructs were used to show that MET16 5'-flanking DNA contains a CP1-dependent upstream activation sequence (UAS). Activity of the UAS required an intact CP1-binding site, and the effects of cis-acting mutations on CP1 binding and UAS activity correlated. In most respects, MET16-CYC1-lacZ reporter gene expression mirrored that of chromosomal MET16; however, the endogenous gene was found to be activated in response to amino acid starvation (general control). The latter mechanism was both GCN4 and CP1 dependent. MET25 was also found to be activated by GCN4, albeit weakly. More importantly, MET25 transcription was strongly CP1 dependent in gcn4 backgrounds. The modulation of MET gene expression by GCN4 can explain discrepancies in the literature regarding CP1 dependence of MET gene transcription. Lastly, micrococcal nuclease digestion and indirect end labeling were used to analyze the chromatin structure of the MET16 locus in wild-type and cep1 cells. The results indicated that CP1 plays no major role in configuring chromatin structure in this region, although localized CP1-specific differences in nuclease sensitivity were detected.
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PMID:Role of the Saccharomyces cerevisiae general regulatory factor CP1 in methionine biosynthetic gene transcription. 789 81

The epidermal growth factor receptors (erbB) constitute an important class of single pass transmembrane receptors involved in the transduction of signals important for cell proliferation and differentiation. Receptor association is a key event in the signal transduction process, but the molecular basis of this interaction is not fully understood. Previous biochemical and genetic studies have suggested that the single transmembrane helices of these receptor proteins might play a role in stabilizing the receptor complexes. To determine if the erbB transmembrane domains could provide a driving force to stabilize the receptor dimers, we carried out a thermodynamic study of these domains expressed as C-terminal fusion proteins with staphylococcal nuclease. Similar fusion constructs have been used successfully to investigate the oligomerization and association thermodynamics of a number of transmembrane sequences, including that of glycophorin A. Using SDS-PAGE analysis and sedimentation equilibrium analytical ultracentrifugation, we do not find strong, specific homo or hetero-interactions between the transmembrane domains of the erbB receptors in micellar solutions. Our results indicate that any preferential interactions between these domains in micellar solutions are extremely modest, of the order of 1 kcal mol(-1) or less. We applied a thermodynamic formalism to assess the effect of weakly interacting TM segments on the behavior of a covalently attached soluble domain. In the case of the ligand-bound EGFR ectodomain, we find that restriction of the ectodomain to the micellar phase by a hydrophobic TM, even in the absence of strong specific interactions, is largely sufficient to account for the previously reported increase in dimerization affinity.
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PMID:The transmembrane domains of ErbB receptors do not dimerize strongly in micelles. 1576 68

Much is known about the distal DNA damage repair response. In particular, many of the enzymes and auxiliary proteins that participate in DNA repair have been characterized. In addition, knowledge of signaling pathways activated in response to DNA damage is increasing. In contrast, comparatively less is known of DNA damage-sensing molecules or of the specific alterations to chromatin structure recognized by such DNA damage sensors. Thus, precisely how chromatin structure is altered in response to DNA damage and how such alterations regulate DNA repair processes remain important unanswered questions. In vertebrates, phosphorylation of the histone variant H2A.X occurs rapidly after double-strand break formation, extends over megabase chromatin domains, and is required for stable accumulation of repair proteins at damage foci. We have shown that reactive oxygen species (ROS)-induced DNA single-strand breaks induce the incorporation of 32P specifically into histone H3. ADP-Ribosylation of histones may stimulate local chromatin relaxation to facilitate the repair process, and, indeed, histone ribosylation preceded DNA damage-induced histone H3 phosphorylation. However, H3 phosphorylation occurred concomitant with overall chromatin condensation, as revealed by decreased sensitivity of chromatin to digestion by micrococcal nuclease and by DAPI staining of nuclei. Inhibitors of the ERK and p38MAPK pathways and inhibition of poly(ADP-ribose) polymerase all reduced ROS-induced H3 phosphorylation, chromatin condensation, and cell death. Precisely how changes in the post-translational modification of histone H3 regulate the survival response remains unclear. Attempts to determine the precise site of histone H3 phosphorylation, putative histone H3 kinases, and histone H3 interacting proteins are underway.
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PMID:Ros-induced histone modifications and their role in cell survival and cell death. 1714

Recent cumulative data show that various transcription factors are recruited to the chromatin in an iron-responsive manner to affect diverse cellular functions in the pathogenic fungus Candida albicans. Here we identified groups of iron-responsive genes in C. albicans by chromatin remodelling analysis at gene promoters, using micrococcal nuclease (MNase) digestion followed by deep sequencing. Chromatin in the promoter regions of iron uptake and utilization genes showed repressed and active configuration, respectively, under iron-replete conditions. GO Term enrichment analysis of genes with differentially remodelled chromatin, in respective promoter locales, suggested that many genes involved in adhesion are also iron-responsive. C. albicans was observed to be more self-adherent (twofold increase) and formed higher biofilm mass (77% increase) in the presence of iron. Furthermore, we identified various known and novel adhesion-related genes with iron-dependent active chromatin profiles that are indicative of potential upregulation under iron-replete conditions. Transcription factor Cph1 that is activated upon Cek1 phosphorylation also showed an active chromatin profile under iron-replete conditions and cells showed iron-responsive Cek1 MAPK phosphorylation in the presence of iron. Thus, iron affects diverse biological functions by modulating chromatin profiles of large gene sets and by signalling through Cek1 MAPK in C. albicans.
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PMID:Iron-responsive chromatin remodelling and MAPK signalling enhance adhesion in Candida albicans. 2488 32

Staphylococcus aureus is not only a common cause of bovine mastitis, but also an agent of food poisoning in humans. In an attempt to determine whether staphylococci causing bovine mastitis could also cause food poisoning, 60 isolates of presumed S. aureus were isolated in the period between March and August 2017 from 3,384 routine, composite, quarter milk samples of individual cows raised on 12 dairy farms in central Italy. Seventeen out of 60 isolates were confirmed as S. aureus after coagulase, thermonuclease, and biochemical tests. These isolates were analyzed by PCR for the presence of the nuc, sea, seb, sec, sed, and see genes. The positive isolates were nuc, 100% (17); sea, 35.29% (6); seb, 5.88% (1); sec, 5.88% (1); sed, 29.41% (5); and see, 47.06% (8). The isolates were also tested with 2 enzyme immunoassay diagnostic kits, one for the screening detection of the production of staphylococcal enterotoxins (SEA, SEB, SEC, SED, SEE) and one for the detection of specific enterotoxin produced by each isolate. Seven out of 17 (41.18%) were enterotoxin producers: 7 produced SEA (41.18%), 1 SEB (5.88%), 1 SEC (5.88%), 5 SED (29.41%), and 6 SEE (35.29%). To further characterize the isolates, they were analyzed by the Kirby Bauer test for susceptibility to 13 antimicrobials (ampicillin, ciprofloxacin, kanamycin, tetracycline, gentamicin, methicillin, nalidixic acid, erythromycin, amoxicillin/clavulanic acid, streptomycin, vancomycin, neomycin, and enrofloxacin), and we detected resistance to ampicillin (52.94%), nalidixic acid (70.59%), erythromycin (5.88%), and amoxicillin/clavulanic acid (17.65%). The isolates were sensitive to the main classes of antimicrobials used for the treatment of bovine subclinical mastitis. The presence of enterotoxin-producing isolates of S. aureus in bovine milk means that a temperature abuse or a breakdown in the thermal treatment of the milk could present a food safety risk, particularly if all enterotoxigenic isolates could potentially produce SEA in milk.
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PMID:Short communication: Characterization of enterotoxin-producing Staphylococcus aureus isolated from mastitic cows. 3059 37


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