Bioleaching of Pyrite by Iron-Oxidizing Acidophiles under the Influence of Reactive Oxygen Species

After 24h of exposure to acidic media, pyrite generates reactive oxygen species (ROS). Freshly-crushed pyrite with grain sizes between 50-100 μm at a 5 % (w/v), pulp density generated 0.17 ± 0.01 mM H2O2, while 10% pyrite generated 0.29 ± 0.01 mM and 30 % pyrite generated approximately 0.83 ± 0.06 mM. These levels of H2O2 inhibit iron oxidation in iron-grown cells of AcidithiobacillusferrooxidansT but not in pyrite-grown cells. ROS originating from pyrite, which was incubated for 24 h in acidic medium, prohibited pyrite dissolution by iron-grown cells, while pyrite-grown cells were adapted to these concentrations of ROS. Periodical addition of 100 μM H2O2 to pyrite cultures inoculated with pyrite-grown cells did not lower iron dissolution as it was observed with iron-grown cells. By high throughput proteomics analysis, an increased expression of proteins related to oxidative stress management, iron-and sulfur oxidation systems, carbon fixation and biofilm formation was observed in biofilm cells grown on pyrite compared to iron-grown cells.</jats:p

How, where and when is SPINK3 bound and removed from mouse sperm?

Sperm capacitation in mammals is a fundamental requirement to acquire their fertilizing capacity. Little is known about the action mechanism of the molecules that prevent capacitation from occurring prematurely. These molecules are known as decapacitation factors (DFs) and they must be removed from the sperm surface for capacitation to occur successfully. Serine protease inhibitor Kazal type 3 (SPINK3) has been proposed as one of these DFs. Here, we evaluate how this protein binds to mouse sperm and its removal kinetics. We describe that SPINK3 is capable of binding to the membrane of mature epididymal sperm through protein-lipid interactions, specifically to lipid rafts subcellular fraction. Moreover, cholera toxin subunit b (CTB) avoids SPINK3 binding. We observe that SPINK3 is removed from the sperm under in vitro capacitating conditions and by the uterine fluid from estrus females. Our ex vivo studies show the removal kinetics of this protein within the female tract, losing SPINK3 formerly from the apical region of the sperm in the uterus and later from the flagellar region within the oviduct. The presence of acrosome-reacted sperm in the female duct concurs with the absence of SPINK3 over its surface.Fil: Nicolli, Anabella Rita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Alonso, Carlos A. I.. McGill University; CanadáFil: Otamendi, Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Cerletti, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Poetsch, Ansgar. Ruhr Universität Bochum; AlemaniaFil: Sharma, Vikram. University of Plymouth; Reino UnidoFil: Zalazar, Lucia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Perez Martinez, Silvina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Cesari, Andreina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin

From protons to OXPHOS supercomplexes and Alzheimer's disease: Structure–dynamics–function relationships of energy-transducing membranes

AbstractBy the elucidation of high-resolution structures the view of the bioenergetic processes has become more precise. But in the face of these fundamental advances, many problems are still unresolved. We have examined a variety of aspects of energy-transducing membranes from large protein complexes down to the level of protons and functional relevant picosecond protein dynamics. Based on the central role of the ATP synthase for supplying the biological fuel ATP, one main emphasis was put on this protein complex from both chloroplast and mitochondria. In particular the stoichiometry of protons required for the synthesis of one ATP molecule and the supramolecular organisation of ATP synthases were examined. Since formation of supercomplexes also concerns other complexes of the respiratory chain, our work was directed to unravel this kind of organisation, e.g. of the OXPHOS supercomplex I1III2IV1, in terms of structure and function. Not only the large protein complexes or supercomplexes work as key players for biological energy conversion, but also small components as quinones which facilitate the transfer of electrons and protons. Therefore, their location in the membrane profile was determined by neutron diffraction. Physico-chemical features of the path of protons from the generators of the electrochemical gradient to the ATP synthase, as well as of their interaction with the membrane surface, could be elucidated by time-resolved absorption spectroscopy in combination with optical pH indicators. Diseases such as Alzheimer's dementia (AD) are triggered by perturbation of membranes and bioenergetics as demonstrated by our neutron scattering studies

A widespread class of reverse transcriptase-related cellular genes

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 108 (2011):20311-20316, doi:10.1073/pnas.1100266108.Reverse transcriptases (RTs) polymerize DNA on RNA templates. They fall into several structurally related but distinct classes, and form an assemblage of RT-like enzymes which, in addition to RTs, also includes certain viral RNA-dependent RNA polymerases (RdRP) polymerizing RNA on RNA templates. It is generally believed that most RT-like enzymes originate from retrotransposons or viruses and have no specific function in the host cell, with telomerases being the only notable exception. Here we report on the discovery and properties of a novel class of RT-related cellular genes collectively named rvt. We present evidence that rvt are not components of retrotransposons or viruses, but single-copy genes with a characteristic domain structure, may contain introns in evolutionarily conserved positions, occur in syntenic regions, and evolve under purifying selection. These genes can be found in all major taxonomic groups including protists, fungi, animals, plants, and even bacteria, although they exhibit patchy phylogenetic distribution in each kingdom. We also show that the RVT protein purified from one of its natural hosts, Neurospora crassa, exists in a multimeric form and has the ability to polymerize NTPs as well as dNTPs in vitro, with a strong preference for NTPs, using Mn2+ as a cofactor. The existence of a previously unknown class of single-copy RT-related genes calls for re-evaluation of the current views on evolution and functional roles of RNA-dependent polymerases in living cells.This work was supported by NSF grant MCB-0821956 to I.A

Haloferax volcanii Proteome Response to Deletion of a Rhomboid Protease Gene

Rhomboids are conserved intramembrane serine proteases involved in cell signaling processes. Their role in prokaryotes is scarcely known and remains to be investigated in <i>Archaea</i>. We previously constructed a rhomboid homologue deletion mutant (Δ<i>rhoII</i>) in <i>Haloferax volcanii</i>, which showed reduced motility, increased novobiocin sensitivity, and an N- glycosylation defect. To address the impact of <i>rhoII</i> deletion on <i>H. volcanii</i> physiology, the proteomes of mutant and parental strains were compared by shotgun proteomics. A total of 1847 proteins were identified (45.8% of <i>H. volcanii</i> predicted proteome), from which 103 differed in amount. Additionally, the mutant strain evidenced 99 proteins with altered electrophoretic migration, which suggested differential post-translational processing/modification. Integral membrane proteins that evidenced variations in concentration, electrophoretic migration, or semitryptic cleavage in the mutant were considered as potential RhoII targets. These included a PrsW protease homologue (which was less stable in the mutant strain), a predicted halocyanin, and six integral membrane proteins potentially related to the mutant glycosylation (S-layer glycoprotein, Agl15) and cell adhesion/motility (flagellin1, HVO_1153, PilA1, and PibD) defects. This study investigated for the first time the impact of a rhomboid protease on the whole proteome of an organism

LonB Protease Is a Novel Regulator of Carotenogenesis Controlling Degradation of Phytoene Synthase in Haloferax volcanii

Cerletti M, Paggi R, Troetschel C, et al. LonB Protease Is a Novel Regulator of Carotenogenesis Controlling Degradation of Phytoene Synthase in Haloferax volcanii. JOURNAL OF PROTEOME RESEARCH. 2018;17(3):1158-1171.The membrane protease LonB is an essential protein in the archaeon Haloferax volcanii and globally impacts its physiology. However, natural substrates of the archaeal Lon protease have not been identified. The whole proteome turnover was examined in a H. volcanii LonB mutant under reduced and physiological protease levels. LC-MS/MS combined with stable isotope labeling was applied for the identification/quantitation of membrane and cytoplasm proteins. Differential synthesis and degradation rates were evidenced for 414 proteins in response to Lon expression. A total of 58 proteins involved in diverse cellular processes showed a degradation pattern (none/very little degradation in the absence of Lon and increased degradation in the presence of Lon) consistent with a LonB substrate, which was further substantiated for several of these candidates by pull-down assays. The most notable was phytoene synthase (PSY), the rate-limiting enzyme in carotenoid biosynthesis. The rapid degradation of PSY upon LonB induction in addition to the remarkable stabilization of this protein and hyperpigmentation phenotype in the Lon mutant strongly suggest that PSY is a LonB substrate. This work identifies for the first time candidate targets of the archaeal Lon protease and establishes proteolysis by Lon as a novel post-translational regulatory mechanism of carotenogenesis

Structure-Activity Relationships of Triple-Action Platinum(IV) Prodrugs with Albumin-Binding Properties and Immunomodulating Ligands

Chemotherapy with platinum complexes is essential for clinical anticancer therapy. However, due to side effects and drug resistance, further drug improvement is urgently needed. Herein, we report on triple-action platinum­(IV) prodrugs, which, in addition to tumor targeting via maleimide-mediated albumin binding, release the immunomodulatory ligand 1-methyl-d-tryptophan (1-MDT). Unexpectedly, structure–activity relationship analysis showed that the mode of 1-MDT conjugation distinctly impacts the reducibility and thus activation of the prodrugs. This in turn affected ligand release, pharmacokinetic properties, efficiency of immunomodulation, and the anticancer activity in vitro and in a mouse model in vivo. Moreover, we could demonstrate that the design of albumin-targeted multi-modal prodrugs using platinum­(IV) is a promising strategy to enhance the cellular uptake of bioactive ligands with low cell permeability (1-MDT) and to improve their selective delivery into the malignant tissue. This will allow tumor-specific anticancer therapy supported by a favorably tuned immune microenvironment

Notch Coordinates Periodontal Ligament Maturation through Regulating Lamin A

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On the Enigma of Glutathione-Dependent Styrene Degradation in Gordonia rubripertincta CWB2

Heine T, Zimmerling J, Ballmann A, et al. On the Enigma of Glutathione-Dependent Styrene Degradation in Gordonia rubripertincta CWB2. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. 2018;84(9): 16.Among bacteria, only a single styrene-specific degradation pathway has been reported so far. It comprises the activity of styrene monooxygenase, styrene oxide isomerase, and phenylacetaldehyde dehydrogenase, yielding phenylacetic acid as the central metabolite. The alternative route comprises ring-hydroxylating enzymes and yields vinyl catechol as central metabolite, which undergoes meta-cleavage. This was reported to be unspecific and also allows the degradation of benzene derivatives. However, some bacteria had been described to degrade styrene but do not employ one of those routes or only parts of them. Here, we describe a novel "hybrid" degradation pathway for styrene located on a plasmid of foreign origin. As putatively also unspecific, it allows metabolizing chemically analogous compounds (e.g., halogenated and/or alkylated styrene derivatives). Gordonia rubripertincta CWB2 was isolated with styrene as the sole source of carbon and energy. It employs an assembled route of the styrene side-chain degradation and isoprene degradation pathways that also funnels into phenylacetic acid as the central metabolite. Metabolites, enzyme activity, genome, transcriptome, and proteome data reinforce this observation and allow us to understand this biotechnologically relevant pathway, which can be used for the production of ibuprofen. IMPORTANCE The degradation of xenobiotics by bacteria is not only important for bioremediation but also because the involved enzymes are potential catalysts in biotechnological applications. This study reveals a novel degradation pathway for the hazardous organic compound styrene in Gordonia rubripertincta CWB2. This study provides an impressive illustration of horizontal gene transfer, which enables novel metabolic capabilities. This study presents glutathione-dependent styrene metabolization in an (actino-) bacterium. Further, the genomic background of the ability of strain CWB2 to produce ibuprofen is demonstrated