Purification,characterization and biological activity of three forms of ferredoxin from the sulfate-reducing bacterium Desulfovibrio gigas

Three forms of ferredoxin FdI, FdI′, and FdII have been isolated from Desulfovibrio gigas, a sulfate reducer. They are separated by a combination of DEAE-cellulose and gel filtration chromatographic procedures. FdI and FdI′ present a slight difference in isoelectric point which enables the separation of the two forms over DEAE-cellulose, while FdII is easily separated from the two other forms by gel filtration. The three forms have the same amino acid composition and are isolated in different aggregation states. Molecular weight determinations by gel filtration gave values of 18 000 for FdI and FdI′ and 24 000 for FdII, whereas a value of 6000 is determined when dissociation is accomplished with sodium dodecyl sulfate. The electronic spectra are different and their ultraviolet-visible absorbance rations are 0.77, 0.87 and 0.68 respectively for FdI, FdI′ and FdII. Despite these differences, the physiological activities of the three forms are similar as far as the reduction of sulfite by molecular hydrogen is concerned.     

Architecture and function of metallopeptidase catalytic domains

The cleavage of peptide bonds by metallopeptidases (MPs) is essential for life. These ubiquitous enzymes participate in all major physiological processes, and so their deregulation leads to diseases ranging from cancer and metastasis, inflammation, and microbial infection to neurological insults and cardiovascular disorders. MPs cleave their substrates without a covalent intermediate in a single‐step reaction involving a solvent molecule, a general base/acid, and a mono‐ or dinuclear catalytic metal site. Most monometallic MPs comprise a short metal‐binding motif (HEXXH), which includes two metal‐binding histidines and a general base/acid glutamate, and they are grouped into the zincin tribe of MPs. The latter divides mainly into the gluzincin and metzincin clans. Metzincins consist of globular ～130–270‐residue catalytic domains, which are usually preceded by N‐terminal pro‐segments, typically required for folding and latency maintenance. The catalytic domains are often followed by C‐terminal domains for substrate recognition and other protein–protein interactions, anchoring to membranes, oligomerization, and compartmentalization. Metzincin catalytic domains consist of a structurally conserved N‐terminal subdomain spanning a five‐stranded β‐sheet, a backing helix, and an active‐site helix. The latter contains most of the metal‐binding motif, which is here characteristically extended to HEXXHXXGXX(H,D). Downstream C‐terminal subdomains are generally shorter, differ more among metzincins, and mainly share a conserved loop—the Met‐turn—and a C‐terminal helix. The accumulated structural data from more than 300 deposited structures of the 12 currently characterized metzincin families reviewed here provide detailed knowledge of the molecular features of their catalytic domains, help in our understanding of their working mechanisms, and form the basis for the design of novel drugs.     

Stimulating action of methyl 12, 12, 12-trifluorofarnesoate on in vitro juvenile hormone III biosynthesis in blattella germanica

Methyl 12, 12, 12-trifluorofarnesoate (MTFF) at a dose of 10 μM, stimulated in vitro juvenile hormone (JH) release in corpora allata (CA) from 6-day-old, freshly ecdysed, and 8-day-old (period of ootheca transport) adult virgin females of Blattella germanica. In addition, MTFF also induced intraglandular accumulation of JH and MF in treated CA. Trifluorofarnesoic acid (TFFA) and trifluorofarnesol (TFF) exhibited the same properties, although to a lesser extent than MTFF. The detection of MTFF in TFFA-treated CA suggested that TFFA and TFF were biotransformed into MTFF by the CA enzymatic system and that this ester might be responsible for the activity observed. Equivalent experiments carried out with farnesoic acid (FA) resulted in a more significant stimulation of JH production. This is not surprising, because exogenous FA is readily epoxidized at C10-C11 double bond and methylated to afford JH. Conversely, analytical data have shown that the C6-C7 double bond of MTFF is epoxidized by the CA enzymatic system, whereas that at C10-C11 remains practically unaltered.     

Chemosystematic implications of flavonoids in Aniba riparia

The trunk wood of Aniba riparia (Nees) Mez (Lauraceae) contains flavokawin-B, (2S)-pinostrombin, (2S)-5, 7-di-O-methylpinocembrin, (2R, 3R)-5, 7-di-O-methylpinobanksin, izalpinin and 3,5, 7-tri-O-methylgalangin. Structural comparison of these flavonoids with the pyrones and neolignans, which characterized all previously examined Aniba spp., leads to a chemical classification of the genus.     

French recommendations for the management of systemic necrotizing vasculitides (polyarteritis nodosa and ANCA-associated vasculitides)

Systemic necrotizing vasculitis comprises a group of diseases resembling polyarteritis nodosa and anti-neutrophil cytoplasmic antibody-associated vasculitis (ANCA): granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and microscopic polyangiitis. The definitive diagnosis is made in cooperation with a reference center for autoimmune diseases and rare systemic diseases or a competency center. The management goals are: to obtain remission and, in the long term, healing; to reduce the risk of relapses; to limit and reduce the sequelae linked to the disease; to limit the side effects and the sequelae linked to the treatments; to improve or at least maintain the best possible quality of life; and to maintain socio-professional integration and/or allow a rapid return to school and/or professional activity. Information and therapeutic education of the patients and those around them are an integral part of the care. All health professionals and patients should be informed of the existence of patient associations. The treatment of vasculitis is based on variable combinations of glucocorticoids and immunosuppressants, chosen and adapted according to the disease concerned, the severity and/or extent of the disease, and the underlying factors (age, kidney function, etc.). Follow-up clinical and paraclinical examinations must be carried out regularly to clarify the progression of the disease, detect and manage treatment failures and possible relapses early on, and limit sequelae and complications (early then late) related to the disease or treatment. A distinction is made between the induction therapy, lasting approximately 3–6 months and aimed at putting the disease into remission, and the maintenance treatment, lasting 12–48 months, or even longer. The role of the increase or testing positive again for ANCA as a predictor of a relapse, which has long been controversial, now seems to have greater consensus: Anti-myeloperoxidase ANCAs are less often associated with a relapse of vasculitis than anti-PR3 ANCA.

     

Meningococcal disease: A paradigm of type‐IV pilus dependent pathogenesis

Neisseria meningitidis (meningococcus) is a Gram‐negative bacterium responsible for two devastating forms of invasive diseases: purpura fulminans and meningitis. Interaction with both peripheral and cerebral microvascular endothelial cells is at the heart of meningococcal pathogenesis. During the last two decades, an essential role for meningococcal type IV pili in vascular colonisation and disease progression has been unravelled. This review summarises 20 years of research on meningococcal type IV pilus‐dependent virulence mechanisms, up to the identification of promising anti‐virulence compounds that target type IV pili.