3 research outputs found
iTRAQ-Based Quantitative Proteomic Analysis of the Antimicrobial Mechanism of Peptide F1 against Escherichia coli
Antimicrobial peptides have received
increasing attention in the
agricultural and food industries due to their potential to control
pathogens. However, to facilitate the development of novel peptide-based
antimicrobial agents, details regarding the molecular mechanisms of
these peptides need to be elucidated. The aim of this study was to
investigate the antimicrobial mechanism of peptide F1, a bacteriocin
found in Tibetan kefir, against Escherichia coli at protein levels using iTRAQ-based quantitative proteomic analysis.
In response to treatment with peptide F1, 31 of the 280 identified
proteins in <i>E. coli</i> showed alterations in their expression,
including 10 down-regulated proteins and 21 up-regulated proteins.
These 31 proteins all possess different molecular functions and are
involved in different molecular pathways, as is evident in referencing
the <i>Kyoto Encyclopedia of Genes and Genomes</i> pathways.
Specifically, pathways that were significantly altered in <i>E. coli</i> in response to peptide F1 treatment include the
tricarboxylic acid cycle, oxidative phosphorylation, glycerophospholipid
metabolism, and the cell cycle–caulobacter pathways, which
was also associated with inhibition of the cell growth, induction
of morphological changes, and cell death. The results provide novel
insights into the molecular mechanisms of antimicrobial peptides
Antibacterial Effects of a Cell-Penetrating Peptide Isolated from Kefir
Kefir
is a traditional fermented milk beverage used throughout
the world for centuries. A cell-penetrating peptide, F3, was isolated
from kefir by Sephadex G-50 gel filtration, DEAE-52 ion exchange,
and reverse-phase high-performance liquid chromatography. F3 was determined
to be a low molecular weight peptide containing one leucine and one
tyrosine with two phosphate radicals. This peptide displayed antimicrobial
activity across a broad spectrum of organisms including several Gram-positive
and Gram-negative bacteria as well as fungi, with minimal inhibitory
concentration (MIC) values ranging from 125 to 500 μg/mL. Cellular
penetration and accumulation of F3 were determined by confocal laser
scanning microscopy. The peptide was able to penetrate the cellular
membrane of Escherichia coli and Staphylococcus aureus. Changes in cell morphology
were observed by scanning electron microscopy (SEM). The results indicate
that peptide F3 may be a good candidate for use as an effective biological
preservative in agriculture and the food industry
DataSheet_1_Nitric oxide-induced lipophagic defects contribute to testosterone deficiency in rats with spinal cord injury.docx
IntroductionMales with acute spinal cord injury (SCI) frequently exhibit testosterone deficiency and reproductive dysfunction. While such incidence rates are high in chronic patients, the underlying mechanisms remain elusive.Methods and resultsHerein, we generated a rat SCI model, which recapitulated complications in human males, including low testosterone levels and spermatogenic disorders. Proteomics analyses showed that the differentially expressed proteins were mostly enriched in lipid metabolism and steroid metabolism and biosynthesis. In SCI rats, we observed that testicular nitric oxide (NO) levels were elevated and lipid droplet-autophagosome co-localization in testicular interstitial cells was decreased. We hypothesized that NO impaired lipophagy in Leydig cells (LCs) to disrupt testosterone biosynthesis and spermatogenesis. As postulated, exogenous NO donor (S-nitroso-N-acetylpenicillamine (SNAP)) treatment markedly raised NO levels and disturbed lipophagy via the AMPK/mTOR/ULK1 pathway, and ultimately impaired testosterone production in mouse LCs. However, such alterations were not fully observed when cells were treated with an endogenous NO donor (L-arginine), suggesting that mouse LCs were devoid of an endogenous NO-production system. Alternatively, activated (M1) macrophages were predominant NO sources, as inducible NO synthase inhibition attenuated lipophagic defects and testosterone insufficiency in LCs in a macrophage-LC co-culture system. In scavenging NO (2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO)) we effectively restored lipophagy and testosterone levels both in vitro and in vivo, and importantly, spermatogenesis in vivo. Autophagy activation by LYN-1604 also promoted lipid degradation and testosterone synthesis.DiscussionIn summary, we showed that NO-disrupted-lipophagy caused testosterone deficiency following SCI, and NO clearance or autophagy activation could be effective in preventing reproductive dysfunction in males with SCI.</p