Structure-based design of a protein immunogen that displays an HIV-1 gp41 neutralizing epitope

Antibody Z13e1 is a relatively broadly neutralizing anti-human immunodeficiency virus type 1 antibody that recognizes the membrane-proximal external region (MPER) of the human immunodeficiency virus type 1 envelope glycoprotein gp41. Based on the crystal structure of an MPER epitope peptide in complex with Z13e1 Fab, we identified an unrelated protein, interleukin (IL)-22, with a surface-exposed region that is structurally homologous in its backbone to the gp41 Z13e1 epitope. By grafting the gp41 Z13e1 epitope sequence onto the structurally homologous region in IL-22, we engineered a novel protein (Z13-IL22-2) that contains the MPER epitope sequence for use as a potential immunogen and as a reagent for the detection of Z13e1-like antibodies. The Z13-IL22-2 protein binds Fab Z13e1 with a K_d of 73 nM. The crystal structure of Z13-IL22-2 in complex with Fab Z13e1 shows that the epitope region is faithfully replicated in the Fab-bound scaffold protein; however, isothermal calorimetry studies indicate that Fab binding to Z13-IL22-2 is not a lock-and-key event, leaving open the question of whether conformational changes upon binding occur in the Fab, in Z13-IL-22, or in both.     

Two GPX-like proteins from Lycopersicon esculentum and Helianthus annuus are antioxidant enzymes with phospholipid hydroperoxide glutathione peroxidase and thioredoxin peroxidase activities.

This study investigated the enzymatic function of two putative plant GPXs, GPXle1 from Lycopersicon esculentum and GPXha2 from Helianthus annuus, which show sequence identities with the mammalian phospholipid hydroperoxide glutathione peroxidase (PHGPX). Both purified recombinant proteins expressed in Escherichia coli show PHGPX activity by reducing alkyl, fatty acid and phospholipid hydroperoxides but not hydrogen peroxide in the presence of glutathione. Interestingly, both recombinant GPXle1 and GPXha2 proteins also reduce alkyl, fatty acid and phospholipid hydroperoxides as well as hydrogen peroxide using thioredoxin as reducing substrate. Moreover, thioredoxin peroxidase (TPX) activities were found to be higher than PHGPX activities in terms of efficiency and substrate affinities, as revealed by their respective Vmax and Km values. We therefore conclude that these two plant GPX-like proteins are antioxidant enzymes showing PHGPX and TPX activities.     

Macroinvertebrate community traits and nitrate removal in stream sediments

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Chemical Composition of Essential Oils of Xanthium spinosum L., an Invasive Species of Corsica

Xanthium spinosum L. is a highly invasive plant originated from South America throughout the world as well as in Corsica Island. The chemical composition of X. spinosum essential oils from 25 Corsican locations was investigated using GC‐FID and GC/MS. Seventy‐four components, which accounted for 96.2% of the total amount, were reported for the first time in the essential oil from aerial parts. The main compounds were eudesma‐4(14),7‐dien‐1β‐ol ( 61 ; 21.3%), germacrene D ( 36 ; 8.8%) and cadalene ( 60 ; 8.7%). Comparison with the literature highlighted the originality of the Corsican essential oil and eudesma‐4(14),7‐dien‐1β‐ol could be used as taxonomical marker to the systematics of the Xanthium genus. The essential oils obtained from separate organs and during the plant vegetative cycle were also studied to gain more knowledge about the correlations between the volatile production and the phenological states of this weed. The production of oxygenated sesquiterpenes was predominant during the plant‐flowering process. The study focuses on direct correlation between the chemical composition of individual 25 oil samples and the morphological differences of the plant. Our results have gained more knowledge about the secondary metabolite production that occurs during the plant life, they could be interesting in order to manage the dispersal of X. spinosum.     

Deregulation of Cdk5 in a mouse model of ALS: toxicity alleviated by perikaryal neurofilament inclusions

Recent studies suggest that increased activity of cyclin-dependent kinase 5 (Cdk5) may contribute to neuronal death and cytoskeletal abnormalities in Alzheimer's disease. We report here such deregulation of Cdk5 activity associated with the hyperphosphorylation of tau and neurofilament (NF) proteins in mice expressing a mutant superoxide dismutase (SOD1(G37R)) linked to amyotrophic lateral sclerosis (ALS). A Cdk5 involvement in motor neuron degeneration is supported by our analysis of three SOD1(G37R) mouse lines exhibiting perikaryal inclusions of NF proteins. Our results suggest that perikaryal accumulations of NF proteins in motor neurons may alleviate ALS pathogenesis by acting as a phosphorylation sink for Cdk5 activity, thereby reducing the detrimental hyperphosphorylation of tau and other neuronal substrates.     

Combined MRI and 31P-MRS Investigations of the ACTA1(H40Y) Mouse Model of Nemaline Myopathy Show Impaired Muscle Function and Altered Energy Metabolism

Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and ³¹Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1–150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (−40%) and specific (−25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level.     

p58IPK-Mediated Attenuation of the Proapoptotic PERK-CHOP Pathway Allows Malignant Progression upon Low Glucose

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Highlights? Transformation-associated glucose shortage triggers ER stress ? The ER stress acts as barrier to malignancy by triggering UPR-dependent apoptosis ? p58^IPK expression removes the UPR barrier by attenuating its PERK-CHOP branch ? This adaptive mechanism enables implementation of UPR cytoprotective features     

TRYPTOPHAN TRANSPORT ACROSS THE BLOOD-BRAIN BARRIER DURING ACUTE HEPATIC FAILURE

Abstract— Tryptophan transport across the blood-brain barrier was studied using a single injection dual isotope label technique, in the following three conditions: normal rats, rats with portacaval shunts, and rats with portacaval shunts followed 65 h later by hepatic artery ligation. In both normal rats and those with acute hepatic failure the tryptophan transport system was found to be comprised of two kinetically distinct components. One component was saturable and obeyed Michaelis-Menten kinetics (normal: V_max= 19.5 nmol.min^?1.g^?1. K_m= 113 μM; hepatic failure: V_max, = 33.8 nmol.min^?1.g^?1, K_m= 108 μM), and the second was a high capacity system which transported tryptophan in direct proportion to concentration over the range tested (normal: K= 0.026 ml.min^?1.g^?1; hepatic failure: K= 0.067 ml.min^?1.g^?1). Since the saturable low capacity component transports several neutral amino acids, and their collective plasma concentration is high in relation to the individual K_ms, tryptophan transport by this component is reduced by competitive inhibition under physiological conditions. Thus it was calculated that in normal rats approx 40% of tryptophan influx occurs via the high capacity system. During acute hepatic failure transport via both components was increased substantially, approximately doubling the rate of tryptophan penetration of the blood-brain barrier at all concentrations tested. The contribution by the high capacity component became even more significant than in normal rats, accounting for about 75% of all tryptophan passage from plasma to brain. Brain tryptophan content was 29.9 nmol/g in normal rats and rose to 45.2 nmol/g in rats with portacaval shunts and 50.5 nmol/g in those with acute hepatic failure, correlating with the increased rate of tryptophan transport. In a previous study we found that plasma competing amino acids were greatly increased during acute hepatic failure. Calculations predict that these increased concentrations would cause a reduction in tryptophan transport by the low capacity system. However, because of the increase in the rate of transport by the high capacity component, net tryptophan entry across the blood-brain barrier was actually increased. This increased rate of transport clearly contributes to the increased content of brain tryptophan found during hepatic failure.