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Antoine Abou Fayad, Jennifer Herrmann, Rolf Müller
Antimicrobial resistance is increasing at an alarming rate. Polymyxin, one of the few antibiotics of last resort, is heavily affected. In this issue of Cell Chemical Biology, Velkov et al. (2018) present a promising alternative: octapeptin lipopeptide antibiotics active against multidrug- and extensively drug-resistant Gram-negative bacteria, which might help overcoming resistance toward polymyxins.
April 19, 2018: Cell Chemical Biology
Tawatchai Thongkongkaew, Wei Ding, Evgeni Bratovanov, Emilia Oueis, Maria Garcia-Altares, Nestor Zaburannyi, Kirsten Harmrolfs, Youming Zhang, Kirstin Scherlach, Rolf Müller, Christian Hertweck
Bacterial infections of agriculturally important plants and mushrooms pose a major threat to human food sources worldwide. However, structures of chemical mediators required by the pathogen for host colonization and infection remain elusive in most cases. Here, we report two types of threonine-tagged lipopeptides conserved among mushroom and rice pathogenic Burkholderia species that facilitate bacterial infection of hosts. Genome mining, metabolic profiling of infected mushrooms and heterologous expression of orphan gene clusters allowed the discovery of these unprecedented metabolites in the mushroom pathogen Burkholderia gladioli (haereogladin, burriogladin), and the plant pathogen Burkholderia glumae (haereoglumin, and burrioglumin)...
April 18, 2018: ACS Chemical Biology
Kosuke Sueyoshi, Miki Yamada, Aki Yamano, Kaori Ozaki, Shimpei Sumimoto, Arihiro Iwasaki, Kiyotake Suenaga, Toshiaki Teruya
Two new pyrrolinone-containing lipopeptides, ypaoamides B (1) and C (2), were isolated from an Okeania sp. marine cyanobacterium collected in Okinawa. Their structures were determined by spectroscopic analysis and Marfey's analysis of acid hydrolysates. Ypaoamides B (1) and C (2) stimulated glucose uptake in cultured rat L6 myotubes. In particular, ypaoamide B (1) showed potent activity and activated AMP-activated protein kinase.
April 18, 2018: Journal of Natural Products
Xue Wang, Haibo Zhou, Hanna Chen, Xiaoshu Jing, Wentao Zheng, Ruijuan Li, Tao Sun, Jiaqi Liu, Jun Fu, Liujie Huo, Yue-Zhong Li, Yuemao Shen, Xiaoming Ding, Rolf Müller, Xiaoying Bian, Youming Zhang
Bacterial genomes encode numerous cryptic biosynthetic gene clusters (BGCs) that represent a largely untapped source of drugs or pesticides. Mining of the cryptic products is limited by the unavailability of streamlined genetic tools in native producers. Precise genome engineering using bacteriophage recombinases is particularly useful for genome mining. However, recombinases are usually host-specific. The genome-guided discovery of novel recombinases and their transient expression could boost cryptic BGC mining...
April 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
Grazia Licciardello, Andrea Caruso, Patrizia Bella, Rodolpho Gheleri, Cinzia P Strano, Alice Anzalone, Emmanouil A Trantas, Panagiotis F Sarris, Nalvo F Almeida, Vittoria Catara
Cyclic lipopeptides (CLPs) are considered as some of the most important secondary metabolites in different plant-associated bacteria, thanks to their antimicrobial, cytotoxic, and surfactant properties. In this study, our aim was to investigate the role of the Quorum Sensing (QS) system, PcoI/PcoR, and the LuxR-type transcriptional regulator RfiA in CLP production in the phytopatogenic bacterium, Pseudomonas corrugata based on our previous work where we reported that the pcoR and rfiA mutants were devoid of the CLPs cormycin and corpeptin production...
2018: Frontiers in Microbiology
Subbaiah Chalivendra, Catherine DeRobertis, Jorge Reyes Pineda, Jong Hyun Ham, Kenneth Damann
The emergence of super-toxigenic strains by recombination is a risk from an intensive use of intraspecific aflatoxin (AF) biocontrol agents (BCAs). Periodical alternation with interspecific-BCAs will be safer since they preclude recombination. We are developing an AF-biocontrol system using rice-associated Bacilli reported previously (RABs). More than 50% of RABs inhibited the growth of multiple A. flavus strains, with RAB4R being the most inhibitory and RAB1 among the least. The fungistatic activity of RAB4R is associated with the lysis of A...
April 16, 2018: Toxins
Alejandro Hernández-Morales, Ramón-Alvar Martínez-Peniche, Jackeline-Lizzeta Arvizu-Gómez, Sofía-María Arvizu-Medrano, Areli Rodríguez-Ontiveros, Miguel-Angel Ramos-López, Juan-Ramiro Pacheco-Aguilar
Bacillus sp. strain MA04 a plant growth-promoting rhizobacteria (PGPR) showed hemolytic activity on blood agar plates, and the supernatant from liquid culture in nutrient broth at 24 h exhibited emulsification activity, suggesting the production of biosurfactants. In antagonist assays, the supernatant showed antifungal activity against phytopathogenic fungi such as Penicillium expansum , Fusarium stilboides , Sclerotium rolfsii y Rhizoctonia solani , finding a reduction of mycelial growth of all fungi tested, ranging from 35 to 69%, this activity was increased with time of culture, accomplishing percentages of inhibition up to 85% with supernatants obtained at 72 h...
June 2018: Indian Journal of Microbiology
Cornelius Domhan, Philipp Uhl, Anna Meinhardt, Stefan Zimmermann, Christian Kleist, Thomas Lindner, Karin Leotta, Walter Mier, Michael Wink
As evolutionary optimized defense compounds, antimicrobial peptides (AMPs) represent a powerful tool against bacterial infections. Ranalexin, an AMP found in the skin of the American bullfrog (Rana catesbeiana), is primarily active against Gram-positive bacteria with a minimum inhibitory concentration (MIC) of 8 - 16 mg/L but shows weaker activity against Gram-negative bacteria (> 64 mg/L). By substitution of 6 N-terminal amino acids by decanoic (C10:0) to myristic (C14:0) acid, we were able to develop lipopeptide derivatives with enhanced antimicrobial activity...
April 9, 2018: International Journal of Antimicrobial Agents
Jing Sun, Shiquan Qian, Jing Lu, Yanan Liu, Fengxia Lu, Xiaomei Bie, Zhaoxin Lu
Bacillus amyloliquefaciens, a gram-positive and soil-dwelling bacterium, could produce secondary metabolites that suppress plant pathogens. In this study, we provided the whole genome sequence results of B. amyloliquefaciens fmbJ which had one circular chromosome of 4,193,344 bp with 4,249 genes, 87 transfer RNA genes, and 27 rRNA genes. In addition, fmbJ was found to contain several gene clusters of antimicrobial lipopeptides (bacillomycin D, surfactin, and fengycin) and bacillomycin D homologues were further comprehensively identified...
April 12, 2018: Journal of Agricultural and Food Chemistry
Bin Liu, Mikko Karttunen
Daptomycin is a cyclic lipopeptide effective against multidrug Gram-positive bacteria. Despite having a net negative charge, it is selective against negatively charged bacterial membranes. It has been established that daptomycin's antibiotic activity is based on directly targeting the bacterial membranes and that this antibacterial activity depends on calcium ions. Importantly, however, both the precise role of ions and the physical mechanisms responsible for daptomycin's action remain poorly understood. We investigate these issues using three types of molecular dynamics simulations: umbrella sampling free energy calculations for a single daptomycin, unbiased simulations for daptomycin tetramers, and unbiased simulations of micellation of daptomycin both in the absence and presence of calcium ions...
April 5, 2018: Biochimica et Biophysica Acta
Javier Rueda Arregui, Surya Prakasarao Kovvasu, Guru V Betageri
The aim of this study was to develop a proliposomal formulation of lipopeptide antibiotic drug daptomycin (DAP) for oral delivery. Thin film hydration was the selected method for preparation of proliposomes. Different phospholipids including soy-phosphatidylcholine (SPC), hydrogenated egg-phosphatidylcholine (HEPC), and distearoyl-phosphatidylcholine (DSPC) were evaluated in combination with cholesterol. The inclusion of surface charge modifiers in the formulation such as dicetyl phosphate (DCP) and stearylamine (SA) to enhance drug encapsulation was also evaluated...
April 3, 2018: AAPS PharmSciTech
Remmer L Salas, Jan Kathryne Dl Garcia, Ana Carmela R Miranda, Windell L Rivera, Ricky B Nellas, Portia Mahal G Sabido
Anoplin (GLLKRIKTLL-NH2 ) is of current interest due to its short sequence and specificity towards bacteria. Recent studies on anoplin have shown that truncation and acylation compromises its antimicrobial activity and specificity, respectively. In this study, truncated analogues (pal-ano-9 to pal-ano-5) of palmitoylated anoplin (pal-anoplin) were synthesized to determine the effects of C-truncation on its bioactivities. Moreover, secondary structure of each analogue using circular dichroism (CD) spectroscopy was determined to correlate with bioactivities...
March 31, 2018: Peptides
Carolina Lema, Rose Y Reins, Rachel L Redfern
Purpose: To determine high-mobility group box 1 (HMGB1) expression during experimental dry eye (EDE) and dry eye-like culture conditions and elucidate its role in corneal dry eye-related inflammation. Methods: EDE was induced in 8- to 12-week-old C57BL/6 mice. Corneal tissue sections and lysates from EDE and untreated mice were evaluated for HMGB1 expression by immunostaining and quantitative real-time PCR (qPCR). For in vitro studies, human corneal epithelial cells (HCEC) were treated with hyperosmolar media, toll-like receptor (TLR) agonists, or proinflammatory cytokines to determine HMGB1 expression...
April 1, 2018: Investigative Ophthalmology & Visual Science
Wenjing Huang, Yan Lang, Abdul Hakeem, Yan Lei, Lu Gan, Xiangliang Yang
Background: Multidrug resistance (MDR) is one of the major obstacles to successful cancer chemotherapy. Developing efficient strategies to reverse MDR remains a major challenge. Surfactin (SUR), a cyclic lipopeptide biosurfactant, has been found to display anticancer activity. Methods: In this paper, SUR was assembled by solvent-emulsion method to load the anticancer drug doxorubicin (DOX). The cytotoxicity of DOX-loaded SUR nanoparticles (DOX@SUR) against DOX-resistant human breast cancer MCF-7/ADR is measured by MTT assay...
2018: International Journal of Nanomedicine
Weijing Cai, Susan Matthew, Qi-Yin Chen, Valerie J Paul, Hendrik Luesch
Two new cyclic lipopeptides termed laxaphycins B4 (1) and A2 (2) were discovered from a collection of the marine cyanobacterium Hormothamnion enteromorphoides, along with the known compound laxaphycin A. The planar structures were solved based on a combined interpretation of 1D and 2D NMR data and mass spectral data. The absolute configurations of the subunits were determined by chiral LC-MS analysis of the hydrolysates, advanced Marfey's analysis and 1D and 2D ROESY experiments. Consistent with similar findings on other laxaphycin A- and B-type peptides, laxaphycin B4 (1) showed antiproliferative effects against human colon cancer HCT116 cells with IC50 of 1...
March 14, 2018: Bioorganic & Medicinal Chemistry
Tamara Lützenburg, Ines Neundorf, Matthias Scholz
Herein, we report the synthesis and characterization of direct carborane-peptide conjugates. Carboranes are non-natural and extremely hydrophobic compounds and turned out to be suitable pharmacophores for diverse biological applications. In this work, we established an efficient procedure for the coupling of carboranes to peptides on solid support. We identified the coupling of carborane-1-carboxylic acids to amino groups to be superior to those with hydroxy- or sulfhydryl-groups. The carborane-peptide conjugates showed remarkably prolonged, and carborane isomer dependent chromatographic retention times...
March 29, 2018: Chemistry and Physics of Lipids
Mohamed Seghir Daas, Albert Remus R Rosana, Jeella Z Acedo, Malika Douzane, Farida Nateche, Salima Kebbouche-Gana, John C Vederas
Bacillus paralicheniformis F47 was isolated from a salty lake in Ain Baida-Ouargla, southern Algeria. The genome contains genes for the production of several bioactive secondary metabolites, including the siderophore bacillibactin, the lipopeptides fengycin, surfactin, and lichenysin, the antibiotics bacitracin and kanosamine, and a putative circular bacteriocin.
March 29, 2018: Genome Announcements
Yohei Takeda, Masahiro Azuma, Kenji Funami, Hiroaki Shime, Misako Matsumoto, Tsukasa Seya
Mycoplasma fermentans -derived diacylated lipoprotein M161Ag (MALP404) is recognized by human/mouse toll-like receptor (TLR) 2/TLR6. Short proteolytic products including macrophage-activating lipopeptide 2 (MALP2) have been utilized as antitumor immune-enhancing adjuvants. We have chemically synthesized a short form of MALP2 named MALP2s ( S -[2,3-bis(palmitoyloxy)propyl]-CGNNDE). MALP2 and MALP2s provoke natural killer (NK) cell activation in vitro but only poorly induce tumor regression using in vivo mouse models loading NK-sensitive tumors...
2018: Frontiers in Immunology
Johannes Arp, Sebastian Götze, Ruchira Mukherji, Derek J Mattern, María García-Altares, Martin Klapper, Debra A Brock, Axel A Brakhage, Joan E Strassmann, David C Queller, Bettina Bardl, Karsten Willing, Gundela Peschel, Pierre Stallforth
Investigating microbial interactions from an ecological perspective is a particularly fruitful approach to unveil both new chemistry and bioactivity. Microbial predator-prey interactions in particular rely on natural products as signal or defense molecules. In this context, we identified a grazing-resistant Pseudomonas strain, isolated from the bacterivorous amoeba Dictyostelium discoideum. Genome analysis of this bacterium revealed the presence of two biosynthetic gene clusters that were found adjacent to each other on a contiguous stretch of the bacterial genome...
March 28, 2018: Proceedings of the National Academy of Sciences of the United States of America
Ambrin Sarwar, Muhammad Nadeem Hassan, Muhammad Imran, Mazhar Iqbal, Saima Majeed, Günter Brader, Angela Sessitsch, Fauzia Yusuf Hafeez
The potential of the Bacillus genus to antagonize phytopathogens is associated with the production of cyclic lipopeptides. Depending upon the type of lipopeptide, they may serve as biocontrol agents that are eco-friendly alternatives to chemical fertilizers. This study evaluates the biocontrol activity of surfactin-producing Bacillus (SPB) strains NH-100 and NH-217 and purified surfactin A from these strains against rice bakanae disease. Biologically active surfactin fractions were purified by HPLC, and surfactin A variants with chain lengths from C12 to C16 were confirmed by LCMS-ESI...
April 2018: Microbiological Research
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