The role of sulfate and its corresponding S(IV)+NO2 formation pathway during the evolution of haze in Beijing

2019 ◽  
Vol 687 ◽  
pp. 741-751 ◽  
Author(s):  
Fange Yue ◽  
Zhouqing Xie ◽  
Pengfei Zhang ◽  
Shaojie Song ◽  
Pengzhen He ◽  
...  
Keyword(s):  
Formation Pathway ◽  
No2 Formation

scholarly journals Characterization of the endoplasmic reticulum–resident peroxidases GPx7 and GPx8 shows the higher oxidative activity of GPx7 and its linkage to oxidative protein folding

2020 ◽  
Vol 295 (36) ◽  
pp. 12772-12785 ◽  
Author(s):  
Shingo Kanemura ◽  
Elza Firdiani Sofia ◽  
Naoya Hirai ◽  
Masaki Okumura ◽  
Hiroshi Kadokura ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Folding ◽  
Physiological Role ◽  
High Reactivity ◽  
Oxidation Activity ◽  
Formation Pathway ◽  
Oxidative Protein Folding ◽  
Redox Active ◽  
Protein Disulfide

Oxidative protein folding occurs primarily in the mammalian endoplasmic reticulum, enabled by a diverse network comprising more than 20 members of the protein disulfide isomerase (PDI) family and more than five PDI oxidases. Although the canonical disulfide bond formation pathway involving Ero1α and PDI has been well-studied so far, the physiological roles of the newly identified PDI oxidases, glutathione peroxidase-7 (GPx7) and -8 (GPx8), are only poorly understood. We here demonstrated that human GPx7 has much higher reactivity with H2O2 and hence greater PDI oxidation activity than human GPx8. The high reactivity of GPx7 is due to the presence of a catalytic tetrad at the redox-active site, which stabilizes the sulfenylated species generated upon the reaction with H2O2. Although it was previously postulated that GPx7 catalysis involved a highly reactive peroxidatic cysteine that can be sulfenylated by H2O2, we revealed that a resolving cysteine instead regulates the PDI oxidation activity of GPx7. We also determined that GPx7 formed complexes preferentially with PDI and P5 in H2O2-treated cells. Altogether, these results suggest that human GPx7 functions as an H2O2-dependent PDI oxidase in cells, whereas PDI oxidation may not be the central physiological role of human GPx8.

scholarly journals A Dispensable Role for Forespore-Specific Gene Expression in Engulfment of the Forespore during Sporulation ofBacillus subtilis

2000 ◽  
Vol 182 (10) ◽  
pp. 2919-2927 ◽  
Author(s):  
Ya-Lin Sun ◽  
Marc D. Sharp ◽  
Kit Pogliano
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Sigma Factor ◽  
Mother Cell ◽  
Spore Production ◽  
Specific Gene ◽  
Ofbacillus Subtilis ◽  
Formation Pathway ◽  
Specific Gene Expression

ABSTRACT During the stage of engulfment in the Bacillus subtilisspore formation pathway, the larger mother cell engulfs the smaller forespore. We have tested the role of forespore-specific gene expression in engulfment using two separate approaches. First, using an assay that unambiguously detects sporangia that have completed engulfment, we found that a mutant lacking the only forespore-expressed engulfment protein identified thus far, SpoIIQ, is able to efficiently complete engulfment under certain sporulation conditions. However, we have found that the mutant is defective, under all conditions, in the expression of the late-forespore-specific transcription factor ςG; thus, SpoIIQ is essential for spore production. Second, to determine if engulfment could proceed in the absence of forespore-specific gene expression, we made use of a strain in which activation of the mother cell-specific sigma factor ςE was uncoupled from forespore-specific gene expression. Remarkably, engulfment occurred in the complete absence of ςF-directed gene expression under the same conditions permissive for engulfment in the absence of SpoIIQ. Our results demonstrate that forespore-specific gene expression is not essential for engulfment, suggesting that the machinery used to move the membranes around the forespore is within the mother cell.

The contribution of biogenic organic matter to aggregation in soil - a review

2021 ◽  
Author(s):  
Tom Guhra ◽  
Katharina Stolze ◽  
Kai Uwe Totsche
Keyword(s):  
Organic Matter ◽  
Extracellular Polymeric Substances ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Close Approach ◽  
Small Scale ◽  
Soil Organisms ◽  
Field Scale ◽  
Formation Pathway

<p>Soil organisms (plants, invertebrates, and microorganisms) are involved in soil structuring and are key factors of aggregation through bioturbation, organic matter (OM) decomposition, and secretion of biogenic OM (e.g., root exudates, mucus and extracellular polymeric substances). At the field scale, soil quality, functions, as well as nutrient cycling usually benefit from the activity of soil organisms that frequently cause substantial changes to soil properties by the formation of aggregates. The biogenic formation pathway of soil aggregates reflects a cascade of small-scale sub-processes (e.g., OM supply, OM adsorption, organo-mineral association formation, their transport, immobilization, and involvement into aggregate structure) that are often portrayed solitarily in literature and demand for a comprehensive framework that consistently describes their synergies and dependencies. Particularly, the role of complexly composed biogenic OM as <strong>bridging/aggregation agent</strong> is controversially discussed in literature, as they may promote as well as inhibit aggregation at the same time. This non-uniform behavior is controlled by the complex interplay of milieu parameters (e.g., ionic strength, temperature, pH and redox-potential) and the physicochemical properties of biogenic OM (e.g., protein-to-polysaccharide-ratio, molecular weight of biopolymers, functional groups, and biopolymer structure). Hence, we discuss biogenic OM with respect to the three different roles in aggregation which can be identified from literature: (I) as <strong>bridging agent</strong> which permits the aggregation due to attraction and surface modifications, (II) as <strong>separation agent</strong> which favors the formation, mobility and transport of organo-mineral associations and inhibits their further involvement into aggregates, and (III) as <strong>gluing agent</strong> which mediates aggregate stability, after an external force provokes a close approach of soil particles. In natural systems, OM may take these roles simultaneously and with varying degree across spatiotemporal scales. Considering this for the discussion of the role of biogenic OM in soil aggregate formation, we will achieve a more detailed and interdisciplinary understanding of its pathways into soil aggregates, which can help to draw comprehensive conclusions from lab and field-scale studies, prospectively.</p>

scholarly journals SpoIIB Localizes to Active Sites of Septal Biogenesis and Spatially Regulates Septal Thinning during Engulfment in Bacillus subtilis

2000 ◽  
Vol 182 (4) ◽  
pp. 1096-1108 ◽  
Author(s):  
Ana R. Perez ◽  
Angelica Abanes-De Mello ◽  
Kit Pogliano
Keyword(s):  
Bacillus Subtilis ◽  
Fusion Protein ◽  
Mother Cell ◽  
Active Sites ◽  
Time Lapse ◽  
Formation Pathway ◽  
Time Lapse Microscopy ◽  
Division Site ◽  
Proposal A

ABSTRACT A key step in the Bacillus subtilis spore formation pathway is the engulfment of the forespore by the mother cell, a phagocytosis-like process normally accompanied by the loss of peptidoglycan within the sporulation septum. We have reinvestigated the role of SpoIIB in engulfment by using the fluorescent membrane stain FM 4-64 and deconvolution microscopy. We have found thatspoIIB mutant sporangia display a transient engulfment defect in which the forespore pushes through the septum and bulges into the mother cell, similar to the situation in spoIID,spoIIM, and spoIIP mutants. However, unlike the sporangia of those three mutants, spoIIB mutant sporangia are able to complete engulfment; indeed, by time-lapse microscopy, sporangia with prominent bulges were found to complete engulfment. Electron micrographs showed that in spoIIB mutant sporangia the dissolution of septal peptidoglycan is delayed and spatially unregulated and that the engulfing membranes migrate around the remaining septal peptidoglycan. These results demonstrate that mother cell membranes will move around septal peptidoglycan that has not been completely degraded and suggest that SpoIIB facilitates the rapid and spatially regulated dissolution of septal peptidoglycan. In keeping with this proposal, a SpoIIB-myc fusion protein localized to the sporulation septum during its biogenesis, discriminating between the site of active septal biogenesis and the unused potential division site within the same cell.

scholarly journals Characterization of organic nitrogen in aerosols at a forest site in the southern Appalachian Mountains

2018 ◽  
Author(s):  
Xi Chen ◽  
Mingjie Xie ◽  
Michael D. Hays ◽  
Eric Edgerton ◽  
Donna Schwede ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Organic Nitrogen ◽  
Bulk Water ◽  
Water Soluble ◽  
Organic N ◽  
Forest Site ◽  
Total N ◽  
Formation Pathway ◽  
Nitro Aromatics

Abstract. This study investigates the composition of organic particulate matter in a remote montane forest in the southeastern U.S., focusing on the role of organic nitrogen (N) in sulfur-containing secondary organic aerosol (nitrooxy-organosulfates) and aerosols associated with biomass burning (nitro-aromatics). Bulk water soluble organic N (WSON) represented ~ 14 % w/w of water soluble total N (WSTN) in PM2.5, on average, across seasonal measurement campaigns conducted in the spring, summer, and fall of 2015. Largest contributions of WSON to WSTN were observed in spring (~ 18 % w/w) and lowest in the fall (~ 10 % w/w). On average, identified nitro-aromatic and nitrooxy-organosulfate compounds accounted for a small fraction of WSON, ranging from ~ 1 % in spring to ~ 4 % in fall, though were observed to contribute as much as 28 % w/w of WSON in individual samples. Highest concentrations of oxidized organic N species occurred during summer (average of 0.65 ngN/m3) along with a greater relative abundance of higher generation oxygenated terpenoic acids, indicating an association with more aged aerosol. Highest concentrations of nitro-aromatics (e.g. nitrocatechol and methyl-nitrocatechol), levoglucosan, and aged SOA tracers were observed during fall, associated with aged biomass burning plumes. Nighttime nitrate radical chemistry is the most likely formation pathway for nitrooxy-organosulfates observed at this low NOx site (generally

scholarly journals Efficient Formation Pathway of Methyl Formate: The Role of OH Radicals on Ice Dust

2021 ◽  
Vol 921 (1) ◽  
pp. L13
Author(s):  
A. Ishibashi ◽  
H. Hidaka ◽  
Y. Oba ◽  
A. Kouchi ◽  
N. Watanabe
Keyword(s):  
Methyl Formate ◽  
Oh Radicals ◽  
Formation Pathway

scholarly journals Biosynthesis of Chloro-β-Hydroxytyrosine, a Nonproteinogenic Amino Acid of the Peptidic Backbone of Glycopeptide Antibiotics

2004 ◽  
Vol 186 (18) ◽  
pp. 6093-6100 ◽  
Author(s):  
Oliver Puk ◽  
Daniel Bischoff ◽  
Claudia Kittel ◽  
Stefan Pelzer ◽  
Stefan Weist ◽  
...  
Keyword(s):  
Amino Acid ◽  
Building Blocks ◽  
Mass Spectrometry Analysis ◽  
Ionization Mass ◽  
Glycopeptide Antibiotics ◽  
P450 Monooxygenase ◽  
Spectrometry Analysis ◽  
Formation Pathway ◽  
Time Point

ABSTRACT The role of the putative P450 monooxygenase OxyD and the chlorination time point in the biosynthesis of the glycopeptide antibiotic balhimycin produced by Amycolatopsis balhimycina were analyzed. The oxyD gene is located directly downstream of the bhp (perhydrolase) and bpsD (nonribosomal peptide synthetase D) genes, which are involved in the synthesis of the balhimycin building block β-hydroxytyrosine (β-HT). Reverse transcriptase experiments revealed that bhp, bpsD, and oxyD form an operon. oxyD was inactivated by an in-frame deletion, and the resulting mutant was unable to produce an active compound. Balhimycin production could be restored (i) by complementation with an oxyD gene, (ii) in cross-feeding studies using A. balhimycina JR1 (a null mutant with a block in the biosynthesis pathway of the building blocks hydroxy- and dihydroxyphenylglycine) as an excretor of the missing precursor, and (iii) by supplementation of β-HT in the growth medium. These data demonstrated an essential role of OxyD in the formation pathway of this amino acid. Liquid chromatography-electrospray ionization-mass spectrometry analysis indicated the biosynthesis of completely chlorinated balhimycin by the oxyD mutant when culture filtrates were supplemented with nonchlorinated β-HT. In contrast, supplementation with 3-chloro-β-HT did not restore balhimycin production. These results indicated that the chlorination time point was later than the stage of free β-HT, most likely during heptapeptide synthesis.

scholarly journals Biochemical characterizations of ER-resident peroxidases, GPx7 and GPx8, reveal their distinct and regulated oxidative activities

2020 ◽  
Author(s):  
Shingo Kanemura ◽  
Elza Firdiani Sofia ◽  
Naoya Hirai ◽  
Masaki Okumura ◽  
Hiroshi Kadokura ◽  
...  
Keyword(s):  
Protein Disulfide Isomerase ◽  
Bond Formation ◽  
Physiological Role ◽  
Oxidation Activity ◽  
Disulfide Isomerase ◽  
Formation Pathway ◽  
Oxidative Protein Folding ◽  
Redox Active ◽  
Protein Disulfide

AbstractIn the mammalian endoplasmic reticulum (ER), the diverse network comprising more than 20 members of the protein disulfide isomerase (PDI) family and more than five PDI oxidases has evolved to promote oxidative protein folding. While the canonical disulfide bond formation pathway constituted by Ero1α and PDI has been well studied so far, mechanistic and physiological bases of newly identified PDI oxidases, glutathione peroxidase-7 (GPx7) and -8 (GPx8), are only poorly understood. We here demonstrated that human GPx7 has much higher reactivity with H2O2 than human GPx8, leading to efficient PDI oxidation. GPx7 forms a catalytic tetrad at the redox active site to react with H2O2 efficiently and stabilize a resultantly generated sulfenylated species. While it was previously postulated that the GPx7 catalysis involved a highly reactive peroxidatic cysteine, a resolving cysteine was found to act to regulate the PDI oxidation activity of GPx7. The present study also revealed that GPx7 formed complexes preferentially with PDI and P5 in H2O2-treated cells. Altogether, human GPx7 functions as an H2O2-dependent PDI oxidase in cells whereas PDI oxidation may not be the central physiological role of human GPx8.

scholarly journals The Role of INAPERTURATE POLLEN1 as a Pollen Aperture Factor Is Conserved in the Basal Eudicot Eschscholzia californica (Papaveraceae)

2021 ◽  
Vol 12 ◽  
Author(s):  
Ismael Mazuecos-Aguilera ◽  
Ana Teresa Romero-García ◽  
Božena Klodová ◽  
David Honys ◽  
María C. Fernández-Fernández ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Pollen Germination ◽  
Pollen Grains ◽  
Functional Study ◽  
Virus Induced Gene Silencing ◽  
Tetrad Stage ◽  
Eschscholzia Californica ◽  
Formation Pathway ◽  
Basal Eudicot

Pollen grains show an enormous variety of aperture systems. What genes are involved in the aperture formation pathway and how conserved this pathway is in angiosperms remains largely unknown. INAPERTURATE POLLEN1 (INP1) encodes a protein of unknown function, essential for aperture formation in Arabidopsis, rice and maize. Yet, because INP1 sequences are quite divergent, it is unclear if their function is conserved across angiosperms. Here, we conducted a functional study of the INP1 ortholog from the basal eudicot Eschscholzia californica (EcINP1) using expression analyses, virus-induced gene silencing, pollen germination assay, and transcriptomics. We found that EcINP1 expression peaks at the tetrad stage of pollen development, consistent with its role in aperture formation, which occurs at that stage, and showed, via gene silencing, that the role of INP1 as an important aperture factor extends to basal eudicots. Using germination assays, we demonstrated that, in Eschscholzia, apertures are dispensable for pollen germination. Our comparative transcriptome analysis of wild-type and silenced plants identified over 900 differentially expressed genes, many of them potential candidates for the aperture pathway. Our study substantiates the importance of INP1 homologs for aperture formation across angiosperms and opens up new avenues for functional studies of other aperture candidate genes.

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