GABA A receptors are the major ionotropic inhibitory neurotransmitter receptors. The endocannabinoid system is a lipid signaling network that modulates different brain functions. Here we show a direct molecular interaction between the two systems. The endocannabinoid 2-arachidonoyl glycerol (2-AG) potentiates GABA A receptors at low concentrations of GABA. Two residues of the receptor located in the transmembrane segment M4 of β 2 confer 2-AG binding. 2-AG acts in a superadditive fashion with the neurosteroid 3α, 21-dihydroxy-5α-pregnan-20-one (THDOC) and modulates δ-subunit-containing receptors, known to be located extrasynaptically and to respond to neurosteroids. 2-AG inhibits motility in CB 1 /CB 2 cannabinoid receptor double-KO, whereas β 2 -KO mice show hypermotility. The identification of a functional binding site for 2-AG in the GABA A receptor may have far-reaching consequences for the study of locomotion and sedation.retrograde signaling | electrophysiology | allosteric modulation

Background:The transport of endocannabinoids across cell membranes is poorly understood. Results: Using a new methodology, we provide experimental evidence for the bidirectional cell membrane transport of endocannabinoids containing an arachidonoyl chain. Conclusion: Endocannabinoid release and uptake are regulated by a membrane-based target independent of intracellular proteins. Significance: A specific bidirectional membrane transporter for the major endocannabinoids is postulated.

A diverse set of 24 novel phages infecting the fire blight pathogen Erwinia amylovora was isolated from fruit production environments in Switzerland. Based on initial screening, four phages (L1, M7, S6, and Y2) with broad host ranges were selected for detailed characterization and genome sequencing. Phage L1 is a member of the Podoviridae, with a 39.3-kbp genome featuring invariable genome ends with direct terminal repeats. Phage S6, another podovirus, was also found to possess direct terminal repeats but has a larger genome (74.7 kbp), and the virus particle exhibits a complex tail fiber structure. Phages M7 and Y2 both belong to the Myoviridae family and feature long, contractile tails and genomes of 84.7 kbp (M7) and 56.6 kbp (Y2), respectively, with direct terminal repeats. The architecture of all four phage genomes is typical for tailed phages, i.e., organized into function-specific gene clusters. All four phages completely lack genes or functions associated with lysogeny control, which correlates well with their broad host ranges and indicates strictly lytic (virulent) lifestyles without the possibility for host lysogenization. Comparative genomics revealed that M7 is similar to E. amylovora virus ⌽Ea21-4, whereas L1, S6, and Y2 are unrelated to any other E. amylovora phage. Instead, they feature similarities to enterobacterial viruses T7, N4, and ⌽EcoM-GJ1. In a series of laboratory experiments, we provide proof of concept that specific two-phage cocktails offer the potential for biocontrol of the pathogen.

BACKGROUND AND PURPOSEPharmacological activation of cannabinoid CB1 and CB2 receptors is a therapeutic strategy to treat chronic and inflammatory pain. It was recently reported that a mixture of natural triterpenes a-and b-amyrin bound selectively to CB1 receptors with a subnanomolar Ki value (133 pM). Orally administered a/b-amyrin inhibited inflammatory and persistent neuropathic pain in mice through both CB1 and CB2 receptors. Here, we investigated effects of amyrins on the major components of the endocannabinoid system. EXPERIMENTAL APPROACHWe measured CB receptor binding interactions of a-and b-amyrin in validated binding assays using hCB1 and hCB2 transfected CHO-K1 cells. Effects on endocannabinoid transport in U937 cells and breakdown using homogenates of BV2 cells and pig brain, as well as purified enzymes, were also studied. KEY RESULTSThere was no binding of either a-or b-amyrin to hCB receptors in our assays (Ki > 10 mM). The triterpene b-amyrin potently inhibited 2-arachidonoyl glycerol (2-AG) hydrolysis in pig brain homogenates, but not that of anandamide. Although b-amyrin only weakly inhibited purified human monoacylglycerol lipase (MAGL), it also inhibited a,b-hydrolases and more potently inhibited 2-AG breakdown than a-amyrin and the MAGL inhibitor pristimerin in BV2 cell and pig brain homogenates. CONCLUSIONS AND IMPLICATIONSWe propose that b-amyrin exerts its analgesic and anti-inflammatory pharmacological effects via indirect cannabimimetic mechanisms by inhibiting the degradation of the endocannabinoid 2-AG without interacting directly with CB receptors. Triterpenoids appear to offer a very broad and largely unexplored scaffold for inhibitors of the enzymic degradation of 2-AG. LINKED ARTICLESThis article is part of a themed section on Cannabinoids. To view the other articles in this section visit http://dx

The micronutrient selenium is found in proteins as selenocysteine (Sec), the 21st amino acid cotranslationally inserted in response to a UGA codon. In vitro studies in archaea and mouse showed that Sec-tRNA Sec formation is a 3-step process starting with serylation of tRNA Sec by seryl-tRNA synthetase (SerRS), phosphorylation of serine to form phosphoserine (