Species specificity, surface exposure, protein expression, immunogenicity, and participation in biofilm formation of Porphyromonas gingivalis HmuY

BACKGROUND: Porphyromonas gingivalis is a major etiological agent of chronic periodontitis. The aim of this study was to examine the species specificity, surface exposure, protein expression, immunogenicity, and participation in biofilm formation of the P. gingivalis heme-binding protein HmuY. RESULTS: HmuY is a unique protein of P. gingivalis since only low amino-acid sequence homology has been found to proteins encoded in other species. It is exposed on the cell surface and highly abundant in the outer membrane of the cell, in outer-membrane vesicles, and is released into culture medium in a soluble form. The protein is produced constitutively at low levels in bacteria grown under high-iron/heme conditions and at higher levels in bacteria growing under the low-iron/heme conditions typical of dental plaque. HmuY is immunogenic and elicits high IgG antibody titers in rabbits. It is also engaged in homotypic biofilm formation by P. gingivalis. Anti-HmuY antibodies exhibit inhibitory activity against P. gingivalis growth and biofilm formation. CONCLUSIONS: Here it is demonstrated that HmuY may play a significant role not only in heme acquisition, but also in biofilm accumulation on abiotic surfaces. The data also suggest that HmuY, as a surface-exposed protein, would be available for recognition by the immune response during chronic periodontitis and the production of anti-HmuY antibodies may inhibit biofilm formation

Diphosphonucleotide phosphatase/phosphodiesterase (PPD1) from yellow lupin (Lupinus luteus L.) contains an iron–manganese center

AbstractYellow lupin diphosphonucleotide phosphatase/phosphodiesterase (PPD1) represents a novel group of enzymes. Here we report that it possesses one iron atom and one manganese atom (1:1 molar ratio) per subunit. The enzyme exhibits visible absorption maximum at ∼530nm. Prolonged oxidation of PPD1 leads to loss of the charge-transfer band and catalytic activity, whereas after reduction PPD1 remains active. Replacement of conserved amino-acid residues coordinating metals results in the loss of enzymatic activity. Despite low amino-acid sequence homology of PPD1 to well-characterized ∼55-kDa purple acid phosphatases, their overall fold, topology of active center and metal content are highly similar

The correlation between Yerba Mate and cancer - a review

Introduction and objective Yerba Mate (YM) is a popular drink obtained from the dried and ground leaves of the Ilex paraguariens. The beneficial effects of Yerba Mate on the cardiovascular system, lipid-lowering, anti-diabetic, hepatoprotective and stimulating properties are known, however, there are also reports supporting its toxicity, that the consumption of Yerba Mate may predispose to the development of cancer. The purpose of this article is to present and organize information on the correlation between drinking Yerba Mate and cancer. Review methods A review of the available literature was performed by searching the PubMed and Google Scholar databases using the following keywords: Yerba Mate and cancer, Yerba Mate. Abbreviated description of the state of knowledge Substances contained in Yerba Mate have a positive impact on the human body. They exert health-promoting effects, e.g. increasing HDL levels and enhancing the antioxidant effect. A particularly desirable effect of Yerba Mate is its modulating effect on the course of the carcinogenesis process. Current knowledge on this subject is not complete. There are no evidences that substances in Yerba Mate without other risk factors increase the risk of oesophageal cancer. It is worth emphasizing that the properties of the Yerba Mate components are related to the reduction of the development of metastases of other cancers. Summary Despite the carcinogenic PAHs contained in the YM extract, there is no clear evidence that drinking it alone, without taking into account the temperature of the drink, could predispose to the development of esophageal cancer. Many substances found in YM have a beneficial effect on the human body

The correlation between Yerba Mate and cancer - a review

Introduction and objective Yerba Mate (YM) is a popular drink obtained from the dried and ground leaves of the Ilex paraguariens. The beneficial effects of Yerba Mate on the cardiovascular system, lipid-lowering, anti-diabetic, hepatoprotective and stimulating properties are known, however, there are also reports supporting its toxicity, that the consumption of Yerba Mate may predispose to the development of cancer. The purpose of this article is to present and organize information on the correlation between drinking Yerba Mate and cancer. Review methods A review of the available literature was performed by searching the PubMed and Google Scholar databases using the following keywords: Yerba Mate and cancer, Yerba Mate. Abbreviated description of the state of knowledge Substances contained in Yerba Mate have a positive impact on the human body. They exert health-promoting effects, e.g. increasing HDL levels and enhancing the antioxidant effect. A particularly desirable effect of Yerba Mate is its modulating effect on the course of the carcinogenesis process. Current knowledge on this subject is not complete. There are no evidences that substances in Yerba Mate without other risk factors increase the risk of oesophageal cancer. It is worth emphasizing that the properties of the Yerba Mate components are related to the reduction of the development of metastases of other cancers. Summary Despite the carcinogenic PAHs contained in the YM extract, there is no clear evidence that drinking it alone, without taking into account the temperature of the drink, could predispose to the development of esophageal cancer. Many substances found in YM have a beneficial effect on the human body

Unique Structure and Stability of HmuY, a Novel Heme-Binding Protein of Porphyromonas gingivalis

Infection, survival, and proliferation of pathogenic bacteria in humans depend on their capacity to impair host responses and acquire nutrients in a hostile environment. Among such nutrients is heme, a co-factor for oxygen storage, electron transport, photosynthesis, and redox biochemistry, which is indispensable for life. Porphyromonas gingivalis is the major human bacterial pathogen responsible for severe periodontitis. It recruits heme through HmuY, which sequesters heme from host carriers and delivers it to its cognate outer-membrane transporter, the TonB-dependent receptor HmuR. Here we report that heme binding does not significantly affect the secondary structure of HmuY. The crystal structure of heme-bound HmuY reveals a new all-β fold mimicking a right hand. The thumb and fingers pinch heme iron through two apical histidine residues, giving rise to highly symmetric octahedral iron co-ordination. The tetrameric quaternary arrangement of the protein found in the crystal structure is consistent with experiments in solution. It shows that thumbs and fingertips, and, by extension, the bound heme groups, are shielded from competing heme-binding proteins from the host. This may also facilitate heme transport to HmuR for internalization. HmuY, both in its apo- and in its heme-bound forms, is resistant to proteolytic digestion by trypsin and the major secreted proteases of P. gingivalis, gingipains K and R. It is also stable against thermal and chemical denaturation. In conclusion, these studies reveal novel molecular properties of HmuY that are consistent with its role as a putative virulence factor during bacterial infection

Copies of the sequence space ω\omega in FF-lattices with applications to Musielak−Orlicz spaces

Let $E$ be a fixed real function $F$-space, i.e., $E$ is an order ideal in $L_0(S,\Sigma,\mu)$ endowed with a monotone $F$-norm $\|\|$ under which $E$ is topologically complete. We prove that $E$ contains an isomorphic (topological) copy of $\omega$, the space of all sequences, if and only if $E$ contains a lattice-topological copy $W$ of $\omega$. If $E$ is additionally discrete, we obtain a much stronger result: $W$ can be a projection band; in particular, $E$ contains a~complemented copy of $\omega$. This solves partially the open problem set recently by W. Wnuk. The property of containing a copy of $\omega$ by a Musielak−Orlicz space is characterized as follows. (1) A sequence space $\ell_{\Phi}$, where $\Phi = (\varphi_n)$, contains a copy of $\omega$ iff $\inf_{n \in \mathbb{N}} \varphi_n (\infty) = 0$, where $\varphi_n (\infty) = \lim_{t \to \infty} \varphi_n (t)$. (2) If the measure $\mu$ is atomless, then $\omega$ embeds isomorphically into $L_{\mathcal{M}} (\mu)$ iff the function $\mathcal{M}_{\infty}$ is positive and bounded on some set $A\in \Sigma$ of positive and finite measure, where $\mathcal{M}_{\infty} (s) = \lim_{n \to \infty} \mathcal{M} (n, s)$, $s\in S$. In particular, (1)' $\ell_\varphi$ does not contain any copy of $\omega$, and (2)' $L_{\varphi} (\mu)$, with $\mu$ atomless, contains a~copy $W$ of $\omega$ iff $\varphi$ is bounded, and every such copy $W$ is uncomplemented in $L_{\varphi} (\mu)$

Developments in Synthetic Application of Selenium(IV) Oxide and Organoselenium Compounds as Oxygen Donors and Oxygen-Transfer Agents

A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV) oxide and hydroperoxide/organoselenium catalyst systems, as “green reagents” for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV) oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts