Lysine catabolism in Haemonchus contortus and Teladorsagia circumcincta

Metabolite profiling of infection-associated metabolic markers of onchocerciasis

The global efforts for onchocerciasis elimination may require additional tools (safe micro and macrofilaricidal drugs, vaccines and biomarkers) as elimination efforts move toward the "end game". Efforts toward the identification of suitable biomarkers have focused on specific protein(s) and/or nucleic acids, but metabolites present an alternative option as they have limited half-lives and are the result of combinatorial effects. In comparison to previously used methodology of LC-MS for metabolomic approaches, we used a non-targeted capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS) to analyze the serum metabolic profiles of Ov-infected and -uninfected individuals (n=20). We identified 286 known metabolites (167 in the cation mode and 119 in the anion mode). In addition, putative metabolites were identified based on KEGG (51), HMDB (37) and HMT (6) databases. One hundred ten of these putative metabolites were quantified based on peak areas of internal standards and their ability to be mapped to known pathways (primary-, carbon-, lipid-, amino acid-, nucleotide and coenzyme-metabolism). Multivariate analysis demonstrated clustering and segregation of some of these metabolites to either the infected or control groups. The levels of serotonin, hypoxanthine, pipecolic acid and inosine were significantly elevated in those with onchocerciasis, whereas the levels of glycerophosphocholine, choline and adenine were significantly lower. This non-targeted metabolomic approach provides a global view of the metabolic variations that occur during Ov infection and thus allow the discovery of key metabolites (and associated pathways) that may serve as useful biomarkers in human onchocerciasis.

Biochemical pathways supporting beta-lactam biosynthesis in the springtail Folsomia candida

Recently, an active set of beta-lactam biosynthesis genes was reported in the genome of the arthropod springtail Folsomia candida (Collembola). Evidence was provided that these genes were acquired through horizontal gene transfer. However, successful integration of fungal- or bacterial-derived beta-lactam biosynthesis into the metabolism of an animal requires the beta-lactam precursor L-α-aminoadipic acid and a phosphopantetheinyl transferase for activation of the first enzyme of the pathway, δ-(L-α-aminoadipoyl)-L-cysteinyl-D-valine synthetase (ACVS). In this study, we characterized these supporting pathways and their transcriptional regulation in F. candida. We identified one phosphopantetheinyl transferase and three pathways for L-α-aminoadipic acid production, distinct from the pathways utilized by microorganisms. We found that after heat shock, the phosphopantetheinyl transferase was co-regulated with ACVS, confirming its role in activating ACVS. Two of the three L-α-aminoadipic acid production pathways were downregulated, while PIPOX, an enzyme participating in the pipecolate pathway, was slightly co-regulated with ACVS. This indicates that L-α-aminoadipic acid may not be a limiting factor in beta-lactam biosynthesis in F. candida, in contrast to microorganisms. In conclusion, we show that all components for L-α-aminoadipic acid synthesis are present and transcriptionally active in F. candida. This demonstrates how springtails could have recruited native enzymes to integrate a beta-lactam biosynthesis pathway into their metabolism after horizontal gene transfer.

Summary: Analysis of phosphopantetheinyl transferases and metabolic pathways for L-α-aminoadipic acid that are required for beta-lactam biosynthesis in the arthropod Folsomia candida.

Significance of the natural occurrence of L- versus D-pipecolic acid: a review

Pipecolic acid naturally occurs in microorganisms, plants, and animals, where it plays many roles, including the interactions between these organisms, and is a key constituent of many natural and synthetic bioactive molecules. This article provides a review of current knowledge on the natural occurrence of pipecolic acid and the known and potential significance of its L- and D-enantiomers in different scientific disciplines. Knowledge gaps with perspectives for future research identified within this article include the roles of the L- versus the D-enantiomer of pipecolic acid in plant resistance, nutrient acquisition, and decontamination of polluted soils, as well as rhizosphere ecology and medical issues.

Molecular and biochemical characterisation of ornithine decarboxylases in the sheep abomasal nematode parasites Teladorsagia circumcincta and Haemonchus contortus

Full length cDNA encoding ornithine decarboxylases (ODC; EC 4.1.1.17) were cloned from the sheep abomasal nematode parasites Teladorsagia circumcincta (TcODC) and Haemonchus contortus (HcODC). The TcODC (1272 bp) and HcODC cDNA (1266 bp) encoded 424 and 422 amino acid proteins respectively. The predicted TcODC amino acid sequence showed 87% identity with HcODC and 65% and 64% with Caenorhabditis elegans and Caenorhabditis briggsae ODC respectively. All binding sites and active regions were completely conserved in both proteins. Soluble N-terminal His-tagged ODC proteins were expressed in Escherichia coli strain BL21, purified and characterised. The recombinant TcODC and HcODC had very similar kinetic properties: K(m) ornithine was 0.2-0.25 mM, optimum [PLP] was 0.3 mM and the pH optima were pH 8. No enzyme activity was detected when arginine was used as substrate. One millimolar difluoromethylornithine (DFMO) completely inhibited TcODC and HcODC activity, whereas 2 mM agmatine did not inhibit activity. The present study showed that ODC is a separate enzyme from arginine decarboxylase and strictly uses ornithine as substrate.