Ml proteins from Mesorhizobium loti and MucR from Brucella abortus: an AT-rich core DNA-target site and oligomerization ability

Mesorhizobium loti contains ten genes coding for proteins sharing high amino acid sequence identity with members of the Ros/MucR transcription factor family. Five of these Ros/MucR family members from Mesorhizobium loti (Ml proteins) have been recently structurally and functionally characterized demonstrating that Ml proteins are DNA-binding proteins. However, the DNA-binding studies were performed using the Ros DNA-binding site with the Ml proteins. Currently, there is no evidence as to when the Ml proteins are expressed during the Mesorhizobium loti life cycle as well as no information concerning their natural DNA-binding site. In this study, we examine the ml genes expression profile in Mesorhizobium loti and show that ml1, ml2, ml3 and ml5 are expressed during planktonic growth and in biofilms. DNA-binding experiments show that the Ml proteins studied bind a conserved AT-rich site in the promoter region of the exoY gene from Mesorhizobium loti and that the proteins make important contacts with the minor groove of DNA. Moreover, we demonstrate that the Ml proteins studied form higher-order oligomers through their N-terminal region and that the same AT-rich site is recognized by MucR from Brucella abortus using a similar mechanism involving contacts with the minor groove of DNA and oligomerization

Raccomandazioni Italiane sulla Pneumologia Riabilitativa. Evidenze scientifiche e messaggi clinico-pratici

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delta-Tocomonoenol: A new vitamin E from kiwi (Actinidia chinensis) fruits

A new vitamin E, d-tocomonoenol, has been isolated from Actinidia chinensis (kiwi) fruits. The new structure, 2,8-dimethyl-2-(4,8,12-trimethyltridec-11-enyl)chroman-6-ol, has been elucidated on the basis of EIMS, 1D, and 2D NMR spectral data. GC–MS analysis of peels and pulps of kiwi showed that the new compound, together with d-tocopherol, is mainly present in the fruit peel, whilst a-tocopherol is present in a similar amount in both matrices. The compound was tested for its radical-scavenging and antioxidant capabilities, by measuring its ability to scavenge DPPH (2,20-diphenyl-1-picrylhydrazyl radical) and anion superoxide radical, and inhibit the formation of methyl linoleate conjugated diene hydroperoxides and TBARS (thiobarbituric acid reactive species)

Phloroglucinols from Myrtaceae: attractive targets for structural characterization, biological properties and synthetic procedures

Myrtaceae Juss. is a very large family of flowering plants, that are a valuable source of bioactive compounds. From the phytochemical point of view, apart from ubiquitous tannins, flavonoid derivatives and volatile oils, Myrtaceae plants are very rich in phloroglucinol derivatives, divided in two principal subclasses: oligomeric acylphloroglucinols and phloroglucinol-terpene adducts. Despite this large structural variability, many studies on phloroglucinols from the Myrtaceae have focused on unique bioactive acylphloroglucinol compounds, named myrtucommulones. Nevertheless, many studies also reported other interesting phloroglucinol derivatives. Therefore, in this review, a comprehensive description of the chemical features of acylphloroglucinols and meroterpenoid-acylphloroglucinols from the Myrtaceae family is presented along with their biological activities. Moreover, since myrtucommulones and their derivatives have become attractive targets for organic chemists, thanks to their structural features and biological activities, relevant approaches and synthetic procedures are herewith discusse

Gallomyrtucommulones G and H, New Phloroglucinol Glycosides, from Bioactive Fractions of Myrtus communis against Staphylococcus Species

Myrtaceae family is a continuous source of antimicrobial agents. In the search for novel antimicrobial agents against Staphylococcus species, bioactive fractions of Myrtus communis L., growing in the Sardinia island (Italy) have been investigated. Their phytochemical analysis led us to isolate and characterize four alkylphloroglucinol glycosides (1–4), three of them gallomyrtucommulones G–H (1,2), and myrtucommulonoside (4) isolated and characterized for the first time. The structures of the new and known compounds, endopreroxide G3 (5), myricetin-3-O-glycosides (6,7) were determined based on the spectroscopic evidence including 1D-/2D-NMR and HR-MS spectrometry. Enriched fractions as well as pure compounds were tested for their antimicrobial activity by broth micro-dilution assay against Staphylococcus epidermidis and S. aureus. Results reported herein demonstrated that gallomyrtucommulone G (1) showed a selective antimicrobial activity against both S. aureus strains (ATCC 29213 and 43300) until 16 µg/mL while gallomyrtucommulone D (3) showed the best growth inhibition value at 64 µg/mL