Inhibition of Biofilm Formation by Modified Oxylipins from the Shipworm Symbiont Teredinibacter turnerae

The bioactivity-guided purification of the culture broth of the shipworm endosymbiont Teredinibacter turnerae strain 991H.S.0a.06 yielded a new fatty acid, turneroic acid (1), and two previously described oxylipins (2–3). Turneroic acid (1) is an 18-carbon fatty acid decorated by a hydroxy group and an epoxide ring. Compounds 1–3 inhibited bacterial biofilm formation in Staphylococcus epidermidis, while only 3 showed antimicrobial activity against planktonic S. epidermidis. Comparison of the bioactivity of 1–3 with structurally related compounds indicated the importance of the epoxide moiety for selective and potent biofilm inhibition.

Inhibition of Biofilm Formation by Modified Oxylipins from the Shipworm Symbiont Teredinibacter turnerae

Bioactivity-guided purification of the culture broth of the shipworm endosymbiont Teredinibacter turnerae 991H.S.0a.06 yielded a new fatty acid, turneroic acid (1), and two previously described oxylipins (2-3). Turneroic acid (1) is an 18-carbon fatty acid decorated by a hydroxy group and an epoxide ring. Compounds 1-3 inhibited bacterial biofilm formation in Staphylococcus epidermidis, while only 3 showed antimicrobial activity against planktonic S. epidermidis. Comparison of the bioactivity of 1-3 with structurally related compounds indicated the importance of the epoxide moiety for selective and potent biofilm inhibition.Abstract Figure

N-myristoyltransferase: Tracing Steps Backwards to Find a Way Forward

N-myristoylation refers to the attachment of a 14-carbon fatty acid onto the N-terminal glycine residue of a target protein. The myristoylation reaction, catalyzed by N-myristoyltrasnferase (NMT), is essential for regulating cellular activities such as signal transduction, proliferation, migration, differentiation, and transformation. Although a considerable amount of research is performed on the overexpression of NMT in pathogenic conditions, a fundamental knowledge gap exists on the evolution of NMT and the functional impact of myristoylation for normal cellular development and functions. We performed evolutionary analyses of the NMT gene and found that most non-vertebrates harbor a single nmt gene and all vertebrates examined harbor two genes; nmt1 and nmt2. For the first time, we report that teleosts harbor two copies of nmt1, named nmt1a and nmt1b. We traced the evolutionary history of the chromosomal fragments hosting NMT1 and NMT2 in humans and found that NMT1 and NMT2 trace back to a single vertebrate ancestral chromosome. We also report the presence of putative nuclear localization sequence (NLS) and amino acid residues flanking NLS. The presence of phosphorylatable amino acid residues flanking the NLS suggests that nuclear localization of NMT is regulated by phosphorylation. The nuclear localization of NMT suggest its potential role in gene transcription.

Hydroxysteroid (17β) dehydrogenase 12 is essential for metabolic homeostasis in adult mice

Hydroxysteroid 17β dehydrogenase 12 (HSD17B12) is suggested to be involved in the elongation of very long chain fatty acids. Previously, we have shown a pivotal role for the enzyme during mouse development. In the present study we generated a conditional Hsd17b12 knockout (HSD17B12cKO) mouse model by breeding mice homozygous for a floxed Hsd17b12 allele with mice expressing the tamoxifen-inducible Cre recombinase at the ROSA26 locus. Gene inactivation was induced by administering tamoxifen to adult mice. The gene inactivation led to a 20% loss of body weight within 6 days, associated with drastic reduction in both white (83% males, 75% females) and brown (65% males, 60% females) fat, likely due to markedly reduced food and water intake. Furthermore, the knockout mice showed sickness behavior and signs of liver toxicity, specifically microvesicular hepatic steatosis and increased serum alanine aminotransferase (4.6-fold in males, 7.7-fold in females). The hepatic changes were more pronounced in females than males. Proinflammatory cytokines, such as interleukin-6 (IL-6), IL-17, and granulocyte colony-stimulating factor, were increased in the HSD17B12cKO mice indicating an inflammatory response. Serum lipidomics study showed an increase in the amount of dihydroceramides, despite the dramatic overall loss of lipids. In line with the proposed role for HSD17B12 in fatty acid elongation, we observed accumulation of ceramides, dihydroceramides, hexosylceramides, and lactosylceramides with shorter than 18-carbon fatty acid side chains in the serum. The results indicate that HSD17B12 is essential for proper lipid homeostasis and HSD17B12 deficiency rapidly results in fatal systemic inflammation and lipolysis in adult mice.

Identification of anti-inflammatory compound/compounds in hexane fraction of Jatropha curcas root extract

Jatropha curcas is a medicinal plant with many therapeutic properties such as anti-inflammatory, anti-malaria, anti-cancer and antioxidant. The root extract has been shown to possess high anti-inflammatory activity. Previously, the compounds responsible for this activity have not been fully elucidated. Two fractions (Fraction 1 and Fraction 2) obtained from a preparative HPLC of the root extract showed significant anti-inflammatory and cytotoxic activities in RAW 264.7 murine macrophage cells with Fraction 1 giving higher nitric oxide (NO) inhibition compared to Fraction 2 and L-NAME. Further purification steps involving column chromatography, thin layer chromatography and analytical HPLC of Fraction 1 produced two fractions labeled as Fraction A and Fraction B. Both fractions showed anti-inflammatory activity without cytotoxic activity in RAW 264.7 cells. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis showed that Fraction A contained a group of 18 carbon fatty acid compounds consisting of 2 oxooctadecanoic acids; 15, 16 dihydroxy 9Z, 12Z octadecadienoic acid; octadecadienoic isomer and 15,16 dihydroxy 9Z, 12Z octadecadienoic acid, 15S, 16S. The 18-carbon fatty acid structure was confirmed by nuclear magnetic resonance (NMR) spectral data. The IC50 value of compounds in Fraction A for anti-inflammatory activity in RAW 264.7 cell line was 434.8±0.75 µg/mL. From the analysis, it can be concluded that Fraction A can be classified under 18 carbon long chain fatty acid group based on LC MS/MS and NMR analysis. This active compound shows an inhibition towards NO activity.

Enzymatic protein depalmitoylation by acyl protein thioesterases

Protein palmitoylation is a dynamic post-translational modification, where the 16-carbon fatty acid, palmitate, is added to cysteines of proteins to modulate protein sorting, targeting and signalling. Palmitate removal from proteins is mediated by acyl protein thioesterases (APTs). Although initially identified as lysophospholipases, increasing evidence suggests APT1 and APT2 are the major APTs that mediate the depalmitoylation of diverse cellular substrates. Here, we describe the conserved functions of APT1 and APT2 across organisms and discuss the possibility that these enzymes are members of a larger family of depalmitoylation enzymes.