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1.
Pseudomonas putida CSV86 utilizes benzyl alcohol via catechol and methylnaphthalenes through detoxification pathway via hydroxymethylnaphthalenes
and naphthaldehydes. Based on metabolic studies, benzyl alcohol dehydrogenase (BADH) and benzaldehyde dehydrogenase (BZDH)
were hypothesized to be involved in the detoxification pathway. BADH and BZDH were purified to apparent homogeneity and were
(1) homodimers with subunit molecular mass of 38 and 57 kDa, respectively, (2) NAD+ dependent, (3) broad substrate specific accepting mono- and di-aromatic alcohols and aldehydes but not aliphatic compounds,
and (4) BADH contained iron and magnesium, while BZDH contained magnesium. BADH in the forward reaction converted alcohol
to aldehyde and required NAD+, while in the reverse reaction it reduced aldehyde to alcohol in NADH-dependent manner. BZDH showed low K
m value for benzaldehyde as compared to BADH reverse reaction. Chemical cross-linking studies revealed that BADH and BZDH do
not form multi-enzyme complex. Thus, the conversion of aromatic alcohol to acid is due to low K
m and high catalytic efficiency of BZDH. Phylogenetic analysis revealed that BADH is a novel enzyme and diverged during the
evolution to gain the ability to utilize mono- and di-aromatic compounds. The wide substrate specificity of these enzymes
enables strain to detoxify methylnaphthalenes to naphthoic acids efficiently. 相似文献
2.
Identification and Characterization of Two Quiescent Porin Genes, nmpC and ompN, in Escherichia coli BE 总被引:1,自引:0,他引:1 下载免费PDF全文
Alexej Prilipov Prashant S. Phale Ralf Koebnik Christine Widmer Jurg P. Rosenbusch 《Journal of bacteriology》1998,180(13):3388-3392
The genomic DNA of the BE strain of Escherichia coli has been scrutinized to detect porin genes that have not been identified so far. Southern blot analysis yielded two DNA segments which proved highly homologous to, yet distinct from, the ompC, ompF, and phoE porin genes. The two genes were cloned and sequenced. One of them, designated ompN, encodes a porin which, due to low levels of expression, has eluded prior identification. The functional properties (single-channel conductance) of the OmpN porin, purified to homogeneity, closely resemble those of the OmpC porin from E. coli K-12. The second DNA fragment detected corresponds to the nmpC gene, which, due to an insertion of an IS1 element in its coding region, is not expressed in E. coli BE. 相似文献
3.
AV Shevchenko IG Budzanivska TP Shevchenko VP Polischuk D Spaar 《Archives Of Phytopathology And Plant Protection》2013,46(2):139-146
The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants. 相似文献
4.
Pseudomonas aeruginosa PP4, Pseudomonas sp. PPD and Acinetobacter lwoffii ISP4 capable of utilizing phthalate isomers were isolated from the soil using enrichment culture technique. The strain ISP4 metabolizes isophthalate, while PPD and PP4 utilizes all three phthalate isomers (ortho-, iso- and tere-) as the sole carbon source. ISP4 utilizes isophthalate (0.1%) more rapidly (doubling time, 0.9 h) compared to PPD (4.64 h), PP4 (7.91 h) and other reported strains so far. The metabolic pathways in these isolates were initiated by dihydroxylation of phthalate isomers. Phthalate is hydroxylated to 3,4-dihydro-3,4-dihydroxyphthalate and 4,5-dihydro-4,5-dihydroxyphthalate in strains PP4 and PPD, respectively; while terephthalate is hydroxylated to 2-hydro-1,2-dihydroxyterephthalate. All three strains hydroxylate isophthalate to 4-hydro-3,4-dihydroxyisophthalate. The generated dihydroxyphthalates were subsequently metabolized to 3,4-dihydroxybenzoate (3,4-DHB) which was further metabolized by ortho ring-cleavage pathway. PP4 and PPD cells grown on phthalate, isophthalate or terephthalate showed respiration on respective phthalate isomer and the activity of corresponding ring-hydroxylating dioxygenase, suggesting the carbon source specific induction of three different ring-hydroxylating dioxygenases. We report, for the first time, the activity of isophthalate dioxygenase and its reductase component in the cell-free extracts. The enzyme showed maximum activity with reduced nicotinamide adenine dinucleotide (NADH) in the pH range 8–8.5. Cells grown on glucose failed to respire on phthalate isomers and 3,4-DHB and showed significantly low activities of the enzymes suggesting that the enzymes are inducible. 相似文献
5.
Fabrizio Grandi Marcia M Colodel Lidianne N Monteiro João Rafael VP Leão Noeme S Rocha 《BMC veterinary research》2010,6(1):45
Backgroud
Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case. 相似文献6.
1-Naphthol 2-hydroxylase (1-NH) which catalyzes the conversion of 1-naphthol to 1,2-dihydroxynaphthalene was purified to homogeneity
from carbaryl-degrading Pseudomonas sp. strain C6. The enzyme was found to be a homodimer with subunit molecular weight of 66 kDa. UV, visible and fluorescence
spectral properties, identification of flavin moiety by HPLC as FAD, and reconstitution of apoenzyme by FAD suggest that enzyme
is FAD-dependent. 1-NH accepts electron from NADH as well as NADPH. Besides 1-naphthol (K
m, 9.1 μM), the enzyme also accepts 5-amino 1-naphthol (K
m, 6.4 μM) and 4-chloro 1-naphthol (K
m, 2.3 μM) as substrates. Enzyme showed substrate inhibition phenomenon at high concentration of 1-naphthol (K
i, 283 μM). Stoichiometric consumption of oxygen and NADH, and biochemical properties suggest that 1-NH belongs to FAD containing
external flavomonooxygenase group of oxido-reductase class of enzymes. Based on biochemical and kinetic properties, 1-NH from
Pseudomonas sp. strain C6 appears to be different than that reported earlier from Pseudomonas sp. strain C4. Chemical modification and protection by 1-naphthol and NADH suggest that His, Arg, Cys, Tyr and Trp are at
or near the active site of 1-NH. 相似文献
7.
Pseudomonas putida CSV86, a naphthalene-degrading organism, exhibited diauxic growth on aromatic compounds plus glucose, with utilization of aromatics in the first log phase and of glucose in the second log phase. Glucose supplementation did not suppress the activity of degrading enzymes, which were induced upon addition of aromatic compounds. The induction was inhibited by chloramphenicol, suggesting that de novo protein synthesis was essential. Cells showed cometabolism of aromatic compounds and organic acids; however, organic acids suppressed glucose utilization. 相似文献
8.
Pseudomonas putida CSV86 utilizes naphthalene (Nap), salicylate (Sal), benzyl alcohol (Balc), and methylnaphthalene (MN) preferentially over
glucose. Methylnaphthalene is metabolized by ring-hydroxylation as well as side-chain hydroxylation pathway. Although the
degradation property was found to be stable, the frequency of obtaining Nap−Sal−MN−Balc− phenotype increased to 11% in the presence of curing agents. This property was transferred by conjugation to Stenotrophomonas maltophilia CSV89 with a frequency of 7 × 10−8 per donor cells. Transconjugants were Nap+Sal+MN+Balc+ and metabolized MN by ring- as well as side-chain hydroxylation pathway. Transconjugants also showed the preferential utilization
of aromatic compounds over glucose indicating transfer of the preferential degradation property. The transferred properties
were lost completely when transconjugants were grown on glucose or 2YT. Attempts to detect and isolate plasmid DNA from CSV86
and transconjugants were unsuccessful. Transfer of degradation genes and its subsequent loss from the transconjugants was
confirmed by PCR using primers specific for 1,2-dihydroxynaphthalene dioxygenase and catechol 2,3-dioxygenase (C23O) as well
as by DNA–DNA hybridizations using total DNA as template and C23O PCR fragment as a probe. These results indicate the involvement
of a probable conjugative element in the: (i) metabolism of aromatic compounds, (ii) ring- and side-chain hydroxylation pathways
for MN, and (iii) preferential utilization of aromatics over glucose. 相似文献
9.
Phthalate isomers and their esters are used heavily in various industries. Excess use and leaching from the product pose them
as major pollutants. These chemicals are toxic, teratogenic, mutagenic and carcinogenic in nature. Various aspects like toxicity,
diversity in the aerobic bacterial degradation, enzymes and genetic organization of the metabolic pathways from various bacterial
strains are reviewed here. Degradation of these esters proceeds by the action of esterases to form phthalate isomers, which
are converted to dihydroxylated intermediates by specific and inducible phthalate isomer dioxygenases. Metabolic pathways
of phthalate isomers converge at 3,4-dihydroxybenzoic acid, which undergoes either ortho- or meta- ring cleavage and subsequently metabolized to the central carbon pathway intermediates. The genes involved in the degradation
are arranged in operons present either on plasmid or chromosome or both, and induced by specific phthalate isomer. Understanding
metabolic pathways, diversity and their genetic regulation may help in constructing bacterial strains through genetic engineering
approach for effective bioremediation and environmental clean up. 相似文献
10.
Dilip C. Badgujar Anjali Anil Angharad E. Green Manalee Vishnu Surve Shilpa Madhavan Alison Beckett Ian A. Prior Barsa K. Godsora Sanket B. Patil Prachi Kadam More Shruti Guha Sarkar Andrea Mitchell Rinti Banerjee Prashant S. Phale Timothy J. Mitchell Daniel R. Neill Prasenjit Bhaumik Anirban Banerjee 《PLoS pathogens》2020,16(11)
The opportunistic pathogen Streptococcus pneumoniae has dual lifestyles: one of an asymptomatic colonizer in the human nasopharynx and the other of a deadly pathogen invading sterile host compartments. The latter triggers an overwhelming inflammatory response, partly driven via pore forming activity of the cholesterol dependent cytolysin (CDC), pneumolysin. Although pneumolysin-induced inflammation drives person-to-person transmission from nasopharynx, the primary reservoir for pneumococcus, it also contributes to high mortality rates, creating a bottleneck that hampers widespread bacterial dissemination, thus acting as a double-edged sword. Serotype 1 ST306, a widespread pneumococcal clone, harbours a non-hemolytic variant of pneumolysin (Ply-NH). Performing crystal structure analysis of Ply-NH, we identified Y150H and T172I as key substitutions responsible for loss of its pore forming activity. We uncovered a novel inter-molecular cation-π interaction, governing formation of the transmembrane β-hairpins (TMH) in the pore state of Ply, which can be extended to other CDCs. H150 in Ply-NH disrupts this interaction, while I172 provides structural rigidity to domain-3, through hydrophobic interactions, inhibiting TMH formation. Loss of pore forming activity enabled improved cellular invasion and autophagy evasion, promoting an atypical intracellular lifestyle for pneumococcus, a finding that was corroborated in in vivo infection models. Attenuation of inflammatory responses and tissue damage promoted tolerance of Ply-NH-expressing pneumococcus in the lower respiratory tract. Adoption of this altered lifestyle may be necessary for ST306 due to its limited nasopharyngeal carriage, with Ply-NH, aided partly by loss of its pore forming ability, facilitating a benign association of SPN in an alternative, intracellular host niche. 相似文献