Cyclotides are plant peptides comprising a circular backbone and three conserved disulfide bonds that confer them with exceptional stability. They were originally discovered in Oldenlandia affinis based on their use in traditional African medicine to accelerate labor. Recently, cyclotides have been identified in numerous plant species of the coffee, violet, cucurbit, pea, potato, and grass families. Their unique structural topology, high stability, and tolerance to sequence variation make them promising templates for the development of peptide-based pharmaceuticals. However, the mechanisms underlying their biological activities remain largely unknown; specifically, a receptor for a native cyclotide has not been reported hitherto. Using bioactivity-guided fractionation of an herbal peptide extract known to indigenous healers as "kalatakalata," the cyclotide kalata B7 was found to induce strong contractility on human uterine smooth muscle cells. Radioligand displacement and second messenger-based reporter assays confirmed the oxytocin and vasopressin V 1a receptors, members of the G proteincoupled receptor family, as molecular targets for this cyclotide. Furthermore, we show that cyclotides can serve as templates for the design of selective G protein-coupled receptor ligands by generating an oxytocin-like peptide with nanomolar affinity. This nonapeptide elicited dose-dependent contractions on human myometrium. These observations provide a proof of concept for the development of cyclotide-based peptide ligands.yclotides are head-to-tail cyclized plant peptides containing three conserved disulfide bonds in a knotted arrangement known as a cyclic cystine-knot motif (1). This confers them high stability (2) and presumably improves their oral bioactivity relative to their linear counterparts (3). They were first discovered in a decoction of Oldenlandia affinis DC. (Rubiaceae) leaves, an herbal remedy used in traditional African medicine during childbirth (4). The observed induction of labor and shortened delivery time were later studied on isolated rat and rabbit uteri and on human uterine strips (4, 5). The peptides responsible for the contractility effects (5) raised interest because they survived boiling, presumably as a result of their unique 3D structure, which was elucidated in 1995 (6). Since then, several plant species of the coffee (Rubiaceae) (7), violet (Violaceae) (8), legume (Fabaceae) (9), potato (Solanaceae) (10) and grass (Poaceae) families (11) have been identified to produce cyclotides. Currently, ∼300 sequences have been reported (12), and the predicted number of >50,000 cyclotides in Rubiaceae alone (7) suggests them to be one of the largest peptide classes within the plant kingdom. Their high intercysteine sequence variability and structural plasticity (13), together with intrinsic bioactivities, make them interesting templates for the development of novel pharmaceuticals (14).However, five decades after the discovery of cyclotides, there still is not any information about specific molecular targe...

species are a complex group of organisms considered to belong to the aerobic actinomycetes. Of the validly described species, many have been implicated as the cause of serious human infections, especially in immunocompromised patients. The genus has a complicated taxonomic history; this is especially true for , the type species of the genus and previously the most frequently reported nocardial taxon from human specimens. We provide background on the current taxonomy of, with a focus on clinically relevant species, and discuss the currently available methods used to accurately identify isolates to the species, complex, or group level.

bThe erm(41) gene confers inducible macrolide resistance in Mycobacterium abscessus subsp. abscessus, calling into question the usefulness of macrolides for treating M. abscessus subsp. abscessus infections. With an extended incubation (14 days), isolates with MICs of >8 g/ml are considered macrolide resistant by current CLSI guidelines. Our goals were to determine the incidence of macrolide susceptibility in U.S. isolates, the validity of currently accepted MIC breakpoints, and the erm(41) sequences associated with susceptibility. Of 349 isolates (excluding those with 23S rRNA gene mutations), 85 (24%) had clarithromycin MICs of <8 g/ml. Sequencing of the erm(41) genes from these isolates, as well as from isolates with MICs of >16 g/ml, including ATCC 19977 T , revealed 10 sequevars. The sequence in ATCC 19977 T was designated sequevar (type) 1; most macrolide-resistant isolates were of this type. Seven sequevars contained isolates with MICs of >16 g/ml. The T28C substitution in erm(41), previously associated with macrolide susceptibility, was identified in 62 isolates (18%) comprising three sequevars, with MICs of <2 (80%), 4 (10%), and 8 (10%) g/ml. No other nucleotide substitution was associated with macrolide susceptibility. We recommend that clarithromycin susceptibility breakpoints for M. abscessus subsp. abscessus be changed from <2 to <4 g/ml and that isolates with an MIC of 8 g/ml have repeat MIC testing or erm sequencing performed. Our studies suggest that macrolides are useful for treating approximately 20% of U.S. isolates of M. abscessus subsp. abscessus. Sequencing of the erm gene of M. abscessus subsp. abscessus will predict inducible macrolide susceptibility.T hree closely related taxa of rapidly growing mycobacteria (RGM) with a controversial species/subspecies status, i.e., Mycobacterium abscessus subsp. abscessus, "M. abscessus subsp. massiliense," and M. abscessus subsp. bolletii, comprise the heterogeneous M. abscessus group (1, 2). A 2013 phylogenetic analysis based on genomic sequencing corroborated previous recommendations that the three taxa should be separated into three subspecies (3). Of these three subspecies, M. abscessus subsp. abscessus and M. abscessus subsp. bolletii, a relatively rare subspecies in the United States, demonstrate the presence of inducible macrolide resistance conferred by a novel erm gene, erm(41) (4).In contrast, the erm(41) gene is generally present in isolates of M. abscessus subsp. massiliense but contains a large, 397-bp deletion (that includes position 28T) that results in a nonfunctional erm(41) gene, and thus isolates do not show inducible macrolide resistance (2).In 2009, Nash and colleagues described two strains (MAB30 and MC1028) of M. abscessus subsp. abscessus which contained a nonfunctional erm gene (4); the strains were not inducibly resistant to clarithromycin, and even after extended incubation, they demonstrated susceptible clarithromycin MICs. The loss of function of the erm genes was associated with a T-to-C substitution at position 28 of th...

Background-Blood pressure (BP) is a heritable trait of major public health concern. The WNK1 and WNK4 genes, which encode proteins in the WNK family of serine-threonine kinases, are involved in renal electrolyte homeostasis. Mutations in the WNK1 and WNK4 genes cause a rare monogenic hypertensive syndrome, pseudohypoaldosteronism type II. We investigated whether polymorphisms in these WNK genes influence BP in the general population. Methods and Results-Associations between 9 single-nucleotide polymorphisms (SNPs) in WNK1 and 1 in WNK4 with ambulatory BP were studied in a population-based sample of 996 subjects from 250 white European families. The heritability estimates of mean 24-hour systolic BP (SBP) and diastolic BP (DBP) were 63.4% and 67.9%, respectively. We found statistically significant (PϽ0.05) associations of several common SNPs and haplotypes in WNK1 with mean 24-hour SBP and/or DBP. The minor allele (C) of rs880054, with a frequency of 44%, reduced mean 24-hour SBP and DBP by 1.37 (95% confidence interval, Ϫ2.45 to Ϫ0.23) and 1.14 (95% confidence interval, Ϫ1.93 to Ϫ0.38) mm Hg, respectively, per copy of the allele. Conclusions-Common variants in