Tryptophan-containing peptide helices: Interactions involving the indole side chain

Two designed peptide sequences containing Trp residues at positions i and i + 5 (Boc-Leu-Trp-Val-Ala-Aib-Leu-Trp-Val-OMe, 1) as well as i and i + 6 (Boc-Leu-Trp-Val-Aib-Ala-Aib-Leu-Trp-Val-OMe, 2) containing one and two centrally positioned Aib residues, respectively, for helix nucleation, have been shown to form stable helices in chloroform solutions. Structures derived from nuclear magnetic resonance (NMR) data reveal six and seven intramolecularly hydrogen-bonded NH groups in peptides 1 and 2, respectively. The helical conformation of octapeptide 1 has also been established in the solid state by X-ray diffraction. The crystal structure reveals an interesting packing motif in which helical columns are stabilized by side chain-backbone hydrogen bonding involving the indole Nε1H of Trp(2) as donor, and an acceptor C=O group from Leu(6) of a neighboring molecule. Helical columns also associate laterally, and strong interactions are observed between the Trp(2) and Trp(7) residues on neighboring molecules. The edge-to-face aromatic interactions between the indoles suggest a potential C-H…π interaction involving the Cζ3H of Trp(2). Concentration dependence of NMR chemical shifts provides evidence for peptide association in solution involving the Trp(2) Nε1H protons, presumably in a manner similar to that observed in the crystal

Temporal Profiling of the Secretome during Adipogenesis in Humans

Adipose tissue plays a key role as a fat-storage depot and as an endocrine organ. Although mouse adipogenesis has been studied extensively, limited studies have been conducted to characterize this process in humans. We carried out a temporal proteomic analysis to interrogate the dynamic changes in the secretome of primary human preadipocytes as they differentiate into mature adipocytes. Using iTRAQ-based quantitative proteomics, we identified and quantified 420 proteins from the secretome of differentiated human adipocytes. Our results revealed that the majority of proteins showed differential expression during the course of differentiation. In addition to adipokines known to be differentially secreted in the course of adipocyte differentiation, we identified a number of proteins whose dynamic expression in this process has not been previously documented. They include collagen triple helix repeat containing 1, cytokine receptor-like factor 1, glypican-1, hepatoma-derived growth factor, SPARC related modular calcium binding protein 1, SPOCK 1, and sushi repeat-containing protein. A bioinformatics analysis using Human Protein Reference Database and Human Proteinpedia revealed that of the 420 proteins identified, 164 proteins possess signal peptides and 148 proteins are localized to the extracellular compartment. Additionally, we employed antibody arrays to quantify changes in the levels of 182 adipokines during human adipogenesis. This is the first large-scale quantitative proteomic stud

Gaspé Flint corn as a seed-to-seed model to study the effect of phosphorus on maize growth and development.

Phosphorus (P) is a vital macronutrient for plant growth and development. Thus, P deficiency represents a bottleneck in the production of maize (Zea mays, L.). Therefore, there is a need for a prompt identification of new P-use efficient lineages and hybrids. The Canadian landrace Gaspé Flint (GF) race of maize was used to identify molecular and morphological traits due to its short life cycle and ease of growing in a hydroponic system under controlled conditions. First, GF was grown in a hydroponic system containing different Pi regimes for 15 d, and harvested tissues were assayed for various morphophysiological and molecular traits. Second, GF was grown in hydroponics under P+ (250 µM) and P-(10 µM) conditions until seed maturity. Pi deficiency led to a lack of synchrony between male and female reproductive organs, reducing fertilization, cob development, and productivity. Although typical Pi deficiency-mediated morphophysiological responses, such as increased root biomass relative to the shoot, accumulation of anthocyanins in the roots and leaves, and elevated acid phosphatase activity in the shoot could be observed in any maize variety, the use of GF abbreviated the analysis of these traits from 120 days in commercial varieties to 40 days. Furthermore, Pi transporters ZmPT5 and ZmPT6 were induced in Pi-deprived roots and leaves and suppressed upon Pi replenishment, suggesting a transcriptional regulation. The study validated the efficacy of GF for accelerating studies on agronomic traits and plant response to stress, from seeds to seeds, in the grass family. The Gaspé Flint corn was confirmed as a plant model to study the effect of phosphorus on the growth and development of maize in a hydroponic system

Isolation of high-affinity phosphate transporters SbPT1 AND SbPT2 in Sorghum bicolor and their characterization in contrasting genotypes.

Phosphate (Pi) availability is highly limited in the acidic soils of the Brazilian savannahs (Cerrado) used for sorghum cultivation. Although several sorghum genotypes contrasting for P use-efficiency have been developed from natural genetic variants, the Pi transport pathway mechanisms in these plants remain unclear. High-affinity Pi transporters play a pivotal role in Pi acquisition by roots and its subsequent mobilization to aerial parts of the plant. We investigated the potential roles of high-affinity Pi transporters in Pi use efficiency in contrasting genotypes of sorghum. A cDNA library prepared from Pi-deprived sorghum seedlings was screened with heterologous Zea mays (maize) Pi transporters ZmPTs, leading to isolation of two homologous sorghum genes referred to as SbPT 1 and SbPT2. Southern analysis revealed that a small gene family represents the SbPTs genes in the sorghum genome. There were significant increases in the transcription levels of SbPT1 and SbPT2 in roots of Pi-deprived seedlings of both Pi-use efficient (101B) and Pi-use inefficient (136B) genotypes. A decrease in the transcript levels of these transporters in 101B and 136B upon Pi replenishment suggested their transcriptional regulation by Pi. Although SbPT1 and SbPT2 were induced in the roots, and in young and old leaves of Pi-deprived sorghum, high transcription levels were observed exclusively in the stems of Pi-efficient genotype 101B under Pi-deprivation. This suggests a role of SbPTs in the efficient mobilization of Pi from the root to the shoot, which could be one of the factors conferring higher Pi-use efficiency in this genotype

Multiomics links global surfactant dysregulation with airflow obstruction and emphysema in COPD

RATIONALE: Pulmonary surfactant is vital for lung homeostasis as it reduces surface tension to prevent alveolar collapse and provides essential immune-regulatory and antipathogenic functions. Previous studies demonstrated dysregulation of some individual surfactant components in COPD. We investigated relationships between COPD disease measures and dysregulation of surfactant components to gain new insights into potential disease mechanisms. METHODS: Bronchoalveolar lavage proteome and lipidome were characterised in ex-smoking mild/moderate COPD subjects (n=26) and healthy ex-smoking (n=20) and never-smoking (n=16) controls using mass spectrometry. Serum surfactant protein analysis was performed. RESULTS: Total phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, surfactant protein (SP)-B, SP-A and SP-D concentrations were lower in COPD versus controls (log2 fold change (log2FC) -2.0, -2.2, -1.5, -0.5, -0.7 and -0.5 (adjusted p<0.02), respectively) and correlated with lung function. Total phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, SP-A, SP-B, SP-D, napsin A and CD44 inversely correlated with computed tomography small airways disease measures (expiratory to inspiratory mean lung density) (r= -0.56, r= -0.58, r= -0.45, r= -0.36, r= -0.44, r= -0.37, r= -0.40 and r= -0.39 (adjusted p<0.05)). Total phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, SP-A, SP-B, SP-D and NAPSA inversely correlated with emphysema (% low-attenuation areas): r= -0.55, r= -0.61, r= -0.48, r= -0.51, r= -0.41, r= -0.31 and r= -0.34, respectively (adjusted p<0.05). Neutrophil elastase, known to degrade SP-A and SP-D, was elevated in COPD versus controls (log2FC 0.40, adjusted p=0.0390), and inversely correlated with SP-A and SP-D. Serum SP-D was increased in COPD versus healthy ex-smoking volunteers, and predicted COPD status (area under the curve 0.85). CONCLUSIONS: Using a multiomics approach, we demonstrate, for the first time, global surfactant dysregulation in COPD that was associated with emphysema, giving new insights into potential mechanisms underlying the cause or consequence of disease

Genome size and ploidy influence angiosperm species' biomass under nitrogen and phosphorus limitation

Research Council of Norway. Grant Number: 196468/v40. NERC. Grant Number: NE/J012106/