Claudia Huber - Academia.edu (original) (raw)

Papers by Claudia Huber

Green Chemistry

Pseudopterosins (Ps), marine diterpene glycosides derived from the marine octocoral Antillogorgia... more Pseudopterosins (Ps), marine diterpene glycosides derived from the marine octocoral Antillogorgia elisabethae, have potent anti-inflammatory activity demonstrated in phase II clinical trials.

Metabolites

The increasing global emergence of multidrug resistant (MDR) pathogens is categorized as one of t... more The increasing global emergence of multidrug resistant (MDR) pathogens is categorized as one of the most important health problems. Therefore, the discovery of novel antimicrobials is of the utmost importance. Lichens provide a rich source of natural products including unique polyketides and polyphenols. Many of them display pharmaceutical benefits. The aim of this study was directed towards the characterization of sunflower oil extracts from the fruticose lichen, Usnea barbata. The concentration of the major polyketide, usnic acid, was 1.6 mg/mL extract as determined by NMR analysis of the crude mixture corresponding to 80 mg per g of the dried lichen. The total phenolics and flavonoids were determined by photometric assays as 4.4 mg/mL (gallic acid equivalent) and 0.27 mg/mL (rutin equivalent) corresponding to 220 mg/g and 13.7 mg/g lichen, respectively. Gram-positive (e.g., Enterococcus faecalis) and Gram-negative bacteria, as well as clinical isolates of infected chickens were s...

Science (New York, N.Y.), Jan 2, 2018

Biological inorganic carbon fixation proceeds through a number of fundamentally different autotro... more Biological inorganic carbon fixation proceeds through a number of fundamentally different autotrophic pathways that are defined by specific key enzymatic reactions. Detection of the enzymatic genes in (meta)genomes is widely used to estimate the contribution of individual organisms or communities to primary production. Here we show that the sulfur-reducing anaerobic deltaproteobacterium is capable of both acetate oxidation and autotrophic carbon fixation, with the tricarboxylic acid cycle operating either in the oxidative or reductive direction, respectively. Under autotrophic conditions, the enzyme citrate synthase cleaves citrate adenosine triphosphate independently into acetyl coenzyme A and oxaloacetate, a reaction that has been regarded as impossible under physiological conditions. Because this overlooked, energetically efficient carbon fixation pathway lacks key enzymes, it may function unnoticed in many organisms, making bioinformatical predictions difficult, if not impossible.

Scientific reports, Jan 22, 2018

A correction to this article has been published and is linked from the HTML and PDF versions of t... more A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Molecular Microbiology, 2015

Thermophilic Campylobacter species colonize the intestine of agricultural and domestic animals co... more Thermophilic Campylobacter species colonize the intestine of agricultural and domestic animals commensally but cause severe gastroenteritis in humans. In contrast to other enteropathogenic bacteria, Campylobacter has been considered to be nonglycolytic, a metabolic property originally used for their taxonomic classification. Contrary to this dogma, we demonstrate that several Campylobacter coli strains are able to utilize glucose as a growth substrate. Isotopologue profiling experiments with 13 C-labeled glucose suggested that these strains catabolize glucose via the pentose phosphate and Entner-Doudoroff (ED) pathways and use glucose efficiently for de novo synthesis of amino acids and cell surface carbohydrates. Whole genome sequencing of glycolytic C. coli isolates identified a genomic island located within a ribosomal RNA gene cluster that encodes for all ED pathway enzymes and a glucose permease. We could show in vitro that a nonglycolytic C. coli strain could acquire glycolytic activity through natural transformation with chromosomal DNA of C. coli and C. jejuni subsp. doylei strains possessing the ED pathway encoding plasticity region. These results reveal for the first time the ability of a Campylobacter species to catabolize glucose and provide new insights into how genetic macrodiversity through intra-and interspecies gene transfer expand the metabolic capacity of this food-borne pathogen.

Database The Journal of Biological Databases and Curation

Supplementary Article: 'Isotopo' a Database Application for Facile Analysis and Managemen... more Supplementary Article: 'Isotopo' a Database Application for Facile Analysis and Management of Mass Isotopomer Data. Database, Oxford University Press, 2014.

KAHL:PLANT METABOLOMICS O-BK, 2013

ABSTRACT

Molecular Microbiology, 2014

The non-glycolytic food-borne pathogen Campylobacter jejuni successfully colonizes the intestine ... more The non-glycolytic food-borne pathogen Campylobacter jejuni successfully colonizes the intestine of various hosts in spite of its restricted metabolic properties. While several amino acids are known to be used by C. jejuni as energy sources, none of these have been found to be essential for growth. Here we demonstrated through phenotype microarray analysis that cysteine utilization increases the metabolic activity of C. jejuni. Furthermore, cysteine was crucial for its growth as C. jejuni was unable to synthesize it from sulphate or methionine. Our study showed that C. jejuni compensates this limited anabolic capacity by utilizing sulphide, thiosulphate, glutathione and the dipeptides γGlu-Cys, Cys-Gly and Gly-Cys as sulphur sources and cysteine precursors. A panel of C. jejuni mutants in putative peptidases and peptide transporters were generated and tested for their participation in the catabolism of the cysteine-containing peptides, and the predicted transporter protein CJJ81176_0236 was discovered to facilitate the growth with the dipeptide Cys-Gly, Ile-Arg and Ile-Trp. It was named Campylobacter peptide transporter A (CptA) and is the first representative of the oligopeptide transporter OPT family demonstrated to participate in the glutathione-derivative Cys-Gly catabolism in prokaryotes. Our study provides new insights into how host- and microbiota-derived substrates like sulphide, thiosulphate and short peptides are used by C. jejuni to compensate its restricted metabolic capacities.

Life

Experimental studies of primordial metabolic evolution are based on multi-component reactions whi... more Experimental studies of primordial metabolic evolution are based on multi-component reactions which typically result in highly complex product mixtures. The detection and structural assignment of these products crucially depends on sensitive and selective analytical procedures. Progress in the instrumentation of these methods steadily lowered the detection limits to concentrations in the pico molar range. At the same time, conceptual improvements in chromatography, nuclear magnetic resonance (NMR) and mass spectrometry dramatically increased the resolution power as well as throughput, now, allowing the simultaneous detection and structural determination of hundreds to thousands of compounds in complex mixtures. In retrospective, the development of these analytical methods occurred stepwise in a kind of evolutionary process that is reminiscent of steps occurring in the evolution of metabolism under chemoautotrophic conditions. This can be nicely exemplified in the analytical procedur...

Science, 1998

In experiments modeling volcanic or hydrothermal settings amino acids were converted into their p... more In experiments modeling volcanic or hydrothermal settings amino acids were converted into their peptides by use of coprecipitated (Ni,Fe)S and CO in conjunction with H 2 S (or CH 3 SH) as a catalyst and condensation agent at 100°C and pH 7 to 10 under anaerobic, ...