Important Features for Protein Foldings in Two Acyl Carrier Proteins from Enterococcus faecalis

The Enteric Bacterium Enterococcus faecalis Elongates and Incorporates Exogenous Short and Medium Chain Fatty Acids Into Membrane Lipids

Enterococcus faecalis incorporates and elongates exogeneous short- and medium-chain fatty acids to chains sufficiently long to enter membrane phospholipid synthesis. The acids are activated by the E. faecalis fatty acid kinase (FakAB) system and converted to acyl-ACP species that can enter the fatty acid synthesis cycle to become elongated. Following elongation the acyl chains are incorporated into phospholipid by the PlsY and PlsC acyltranferases. This process has little effect on de novo fatty acid synthesis in the case of short-chain acids, but a greater effect with medium-chain acids. Incorporation of exogenous short-chain fatty acids in E. faecalis was greatly increased by overexpression of either AcpA, the acyl carrier protein of fatty acid synthesis, or the phosphate acyl transferase PlsX. The PlsX of Lactococcus lactis was markedly superior to the E. faecalis PlsX in incorporation of short-chain but not long-chain acids. These manipulations also allowed unsaturated fatty acids of lengths too short for direct transfer to the phospholipid synthesis pathway to be elongated and support growth of E. faecalis unsaturated fatty acid auxotrophic strains. Short- and medium-chain fatty acids can be abundant in the human gastrointestinal tract and their elongation by E. faecalis would conserve energy and carbon by relieving the requirement for total de novo synthesis of phospholipid acyl chains.

Characterization of active peptides derived from three leeches and comparison of their anti-thrombotic mechanisms using the tail vein thrombosis model in mice and metabonomics

Background and aims: The increasing incidence of cardiovascular diseases has created an urgent need for safe and effective anti-thrombotic agents. Leech, as a traditional Chinese medicine, has the effect of promoting blood circulation and removing blood stasis, but its real material basis and mechanism of action for the treatment of diseases such as blood stasis and thrombosis have not been reported. Methods: In this study, Whitmania Pigra Whitman (WPW), Hirudo nipponica Whitman (HNW) and Whitmania acranutata Whitman (WAW) were hydrolyzed by biomimetic enzymatic hydrolysis to obtain the active peptides of WPW (APP), the active peptides of HNW (APH) and the active peptides of WAW (APA), respectively. Then their structures were characterized by sykam amino acid analyzer, fourier transform infrared spectrometer (FT-IR), circular dichroism (CD) spectrometer and LC-MS. Next, the anti-thrombotic activities of APP, APH and APA were determined by carrageenan-induced tail vein thrombosis model in mice, and the anti-thrombotic mechanisms of high-dose APP group (HAPP), high-dose APH group (HAPH) and high-dose APA group (HAPA) were explored based on UHPLC-Q-Exactive Orbitrap mass spectrometry. Results: The results showed that the amino acid composition of APP, APH and APA was consistent, and the proportion of each amino acid was few different. The results of FT-IR and CD showed that there were no significant differences in the proportion of secondary structures (such as β-sheet and random coil) and infrared absorption peaks between APP, APH and APA. Mass spectrometry data showed that there were 43 common peptides in APP, APH and APA, indicating that the three have common material basis. APP, APH and APA could significantly inhibit platelet aggregation, reduce black-tail length, whole blood viscosity (WBV), plasma viscosity (PV), and Fibrinogen (FIB), and prolong coagulation time, including activated partial thrombin time (APTT), prothrombin time (PT) and thrombin time (TT). In addition, 24 metabolites were identified as potential biomarkers associated with thrombosis development. Among these, 19, 23, and 20 metabolites were significantly normalized after administration of HAPP, HAPH, and HAPA in the mice, respectively. Furthermore, the intervention mechanism of HAPP, HAPH and HAPA on tail vein thrombosis mainly involved in linoleic acid metabolism, primary bile acid biosynthesis and ether lipid metabolism. Conclusion: Our findings suggest that APP, APH and APA can exert their anti-blood stasis and anti-thrombotic activities by interfering with disordered metabolic pathways in vivo, and there is no significant difference in their efficacies.