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Biochemical and Biophysical Research... Aug 2024MPIase is a glycolipid involved in protein insertion into and preprotein translocation across the cytoplasmic membranes of E. coli. MPIase is upregulated in the cold...
MPIase is a glycolipid involved in protein insertion into and preprotein translocation across the cytoplasmic membranes of E. coli. MPIase is upregulated in the cold conditions to overcome the cold-sensitive protein export. CdsA, a CDP-diacylglycerol synthase, catalyzes the first reaction in MPIase biosynthesis. An open reading frame for a peptide of 50 amino acids is encoded immediately after ispU, a neighboring upstream gene of cdsA, and overlaps cdsA to a large extent. Mutational analysis revealed that the expression of this peptide is essential for upregulation of MPIase in the cold. Consistently, expression of this peptide in trans resulted in cold upregulation of MPIase. We therefore named this peptide MucA after its function (MPIase upregulation in the cold). When the partially purified MucA was added to the reaction of the intermediate in MPIase biosynthesis, a significant increase in the product formation was observed, supporting the function of MucA. The possible role of MucA in MPIase biosynthesis is discussed.
Topics: Cold Temperature; Escherichia coli; Escherichia coli Proteins; Glycolipids; Up-Regulation; Amino Acid Sequence; Peptides; Gene Expression Regulation, Bacterial; Nucleotidyltransferases; Membrane Transport Proteins
PubMed: 38781662
DOI: 10.1016/j.bbrc.2024.150148 -
The Biochemical Journal Jul 2024The reaction centre-light harvesting 1 (RC-LH1) core complex is indispensable for anoxygenic photosynthesis. In the purple bacterium Rhodobacter (Rba.) sphaeroides...
The reaction centre-light harvesting 1 (RC-LH1) core complex is indispensable for anoxygenic photosynthesis. In the purple bacterium Rhodobacter (Rba.) sphaeroides RC-LH1 is produced both as a monomer, in which 14 LH1 subunits form a C-shaped antenna around 1 RC, and as a dimer, where 28 LH1 subunits form an S-shaped antenna surrounding 2 RCs. Alongside the five RC and LH1 subunits, an additional polypeptide known as PufX provides an interface for dimerisation and also prevents LH1 ring closure, introducing a channel for quinone exchange that is essential for photoheterotrophic growth. Structures of Rba. sphaeroides RC-LH1 complexes revealed several new components; protein-Y, which helps to form the quinone channel; protein-Z, of unknown function and seemingly unique to dimers; and a tightly bound sulfoquinovosyl diacylglycerol (SQDG) lipid that interacts with two PufX arginine residues. This lipid lies at the dimer interface alongside weak density for a second molecule, previously proposed to be an ornithine lipid. In this work we have generated strains of Rba. sphaeroides lacking protein-Y, protein-Z, SQDG or ornithine lipids to assess the roles of these previously unknown components in the assembly and activity of RC-LH1. We show that whilst the removal of either protein-Y, protein-Z or ornithine lipids has only subtle effects, SQDG is essential for the formation of RC-LH1 dimers but its absence has no functional effect on the monomeric complex.
Topics: Rhodobacter sphaeroides; Light-Harvesting Protein Complexes; Bacterial Proteins; Protein Multimerization; Glycolipids; Models, Molecular; Crystallography, X-Ray
PubMed: 38780411
DOI: 10.1042/BCJ20240125 -
Pediatric Research May 2024Fat malabsorption in children with cystic fibrosis (CF) leads to poor nutritional status and altered colonic microbiota. This study aimed at establishing the faecal...
BACKGROUND
Fat malabsorption in children with cystic fibrosis (CF) leads to poor nutritional status and altered colonic microbiota. This study aimed at establishing the faecal lipid profile in children with CF, and exploring associations between the faecal lipidome and microbiota.
METHODS
Cross-sectional observational study with children with CF and an age-matched control group. Faecal lipidome was analysed by UHLC-HRMS and microbiota profiling by 16S rRNA amplicon sequencing.
RESULTS
Among 234 identified lipid species, five lipidome clusters (LC) were obtained with significant differences in triacylglycerols (TG), diacylglycerols (DG), monoacylglycerols (MG) and fatty-acids (FA): LC1 subjects with good digestion and absorption: low TG and low MG and FA; LC2 good digestion and poor absorption: low TG and high MG and FA; LC3 Mild digestion and poor absorption: intermediate TG and high MG and FA; LC4 poor digestion and absorption: high TG and high MG and FA; LC5 outliers. Bacteroidota and Verrucomicrobiota decreased over LC1-LC4, while Proteobacteria increased. Nutritional status indicators were significantly higher in LC1 and decreased over LC2-LC4.
CONCLUSION
Assessing faecal lipidome may be relevant to determine how dietary lipids are digested and absorbed. This new evidence might be a method to support targeted nutritional interventions towards reverting fat maldigestion or malabsorption.
IMPACT
Lipidomic analysis enabled the identification of the lipid species related to maldigestion (triglycerides) or malabsorption (monoglycerides and fatty acids). Children with cystic fibrosis can be grouped depending on the faecal lipidome profile related to dietary fat maldigestion or malabsorption. The lipidome profile in faeces is related to the composition of microbiota and nutritional status indicators.
PubMed: 38778229
DOI: 10.1038/s41390-024-03209-0 -
Molecular Biology of the Cell Jul 2024Lipin 1 is an ER enzyme that produces diacylglycerol, the lipid intermediate that feeds into the synthesis of glycerophospholipids for membrane expansion or...
Lipin 1 is an ER enzyme that produces diacylglycerol, the lipid intermediate that feeds into the synthesis of glycerophospholipids for membrane expansion or triacylglycerol for storage into lipid droplets. CTD-Nuclear Envelope Phosphatase 1 (CTDNEP1) regulates lipin 1 to restrict ER membrane synthesis, but a role for CTDNEP1 in lipid storage in mammalian cells is not known. Furthermore, how NEP1R1, the regulatory subunit of CTDNEP1, contributes to these functions in mammalian cells is not fully understood. Here, we show that CTDNEP1 is reliant on NEP1R1 for its stability and function in limiting ER expansion. CTDNEP1 contains an amphipathic helix at its N-terminus that targets to the ER, nuclear envelope and lipid droplets. We identify key residues at the binding interface of CTDNEP1 and NEP1R1 and show that they facilitate complex formation in vivo and in vitro. We demonstrate that NEP1R1 binding to CTDNEP1 shields CTDNEP1 from proteasomal degradation to regulate lipin 1 and restrict ER size. Unexpectedly, NEP1R1 was not required for CTDNEP1's role in restricting lipid droplet biogenesis. Thus, the reliance of CTDNEP1 function on NEP1R1 depends on cellular demands for membrane production versus lipid storage. Together, our work provides a framework into understanding how the ER regulates lipid synthesis under different metabolic conditions.
Topics: Endoplasmic Reticulum; Nuclear Envelope; Humans; Phosphatidate Phosphatase; Animals; Lipid Metabolism; Mice; Lipid Droplets; HEK293 Cells; Protein Binding; Lipids; Nuclear Proteins
PubMed: 38776127
DOI: 10.1091/mbc.E23-09-0382 -
ACS Infectious Diseases Jun 2024Toward human immunodeficiency virus type-1 (HIV-1) cure, cells latently infected with HIV-1 must be eliminated from people living with HIV-1. We previously developed a...
Toward human immunodeficiency virus type-1 (HIV-1) cure, cells latently infected with HIV-1 must be eliminated from people living with HIV-1. We previously developed a protein kinase C (PKC) activator, diacylglycerol (DAG)-lactone derivative , with high HIV-1 latency-reversing activity, based on YSE028 () as a lead compound and found that the activity was correlated with binding affinity for PKC and stability against esterase-mediated hydrolysis. Here, we synthesized new DAG-lactone derivatives not only containing a tertiary ester group or an isoxazole surrogate but also several symmetric alkylidene moieties to improve HIV-1 latency reversing activity. Compound , with a dimethyl group at the α-position of the ester group, exerted twice higher HIV-1 latency reversing activity than compound , and compound , with the isoxazole moiety, was significantly active. In addition, DAG-lactone derivatives with moderate hydrophobicity and potent biostability showed high biological activity.
Topics: Humans; HIV-1; Virus Latency; Lactones; Anti-HIV Agents; Diglycerides; HIV Infections; Protein Kinase C
PubMed: 38771724
DOI: 10.1021/acsinfecdis.4c00194 -
The Plant Journal : For Cell and... May 2024Diacylglycerol acyltransferase1 (DGAT1) is the major enzyme that synthesizes triacylglycerols (TAG) during Arabidopsis seed development. Mutant dgat1 seeds possess low...
Diacylglycerol acyltransferase1 (DGAT1) is the major enzyme that synthesizes triacylglycerols (TAG) during Arabidopsis seed development. Mutant dgat1 seeds possess low oil content in addition to a high polyunsaturated fatty acid (PUFA) composition. Two genes encoding endoplasmic reticulum localized desaturase enzymes, fatty acid desaturase2 (FAD2) and fatty acid desaturase3 (FAD3), were upregulated in both dgat1-1 and dgat1-2 developing seeds. Crosses between both dgat1 mutant alleles and fad2-1 failed to generate plants homozygous for both dgat1 and fad2. Reciprocal crosses with wild-type plants demonstrated that both male and female dgat1 fad2 gametophytes were viable. Siliques from DGAT1/dgat1-1 fad2-1/fad2-1 and dgat1-1/dgat1-1 FAD2/fad2-1 possessed abnormal looking seeds that were arrested in the torpedo growth stage. Approximately 25% of the seeds exhibited this arrested phenotype, genetically consistent with them possessing the double homozygous dgat1 fad2 genotype. In contrast, double homozygous dgat1-1 fad3-2 mutant plants were viable. Seeds from these plants possessed higher levels of 18:2 while their fatty acid content was lower than dgat1 mutant controls. The results are consistent with a model where in the absence of DGAT1 activity, desaturation of fatty acids by FAD2 becomes essential to provide PUFA substrates for phospholipid:diacylglycerol acyltransferase (PDAT) to synthesize TAG. In a dgat1 fad2 mutant, seed development is aborted because TAG is unable to be synthesized by either DGAT1 or PDAT.
PubMed: 38762880
DOI: 10.1111/tpj.16805 -
Biomedicine & Pharmacotherapy =... Jun 2024Hypoxic-ischemic encephalopathy (HIE), resulting from a lack of blood flow and oxygen before or during newborn delivery, is a leading cause of cerebral palsy and...
Hypoxic-ischemic encephalopathy (HIE), resulting from a lack of blood flow and oxygen before or during newborn delivery, is a leading cause of cerebral palsy and neurological disability in children. Therapeutic hypothermia (TH), the current standard of care in HIE, is only beneficial in 1 of 7-8 cases. Therefore, there is a critical need for more efficient treatments. We have previously reported that omega-3 (n-3) fatty acids (FA) carried by triglyceride (TG) lipid emulsions provide neuroprotection after experimental hypoxic-ischemic (HI) injury in neonatal mice. Herein, we propose a novel acute therapeutic approach using an n-3 diglyceride (DG) lipid emulsions. Importantly, n-3 DG preparations had much smaller particle size compared to commercially available or lab-made n-3 TG emulsions. We showed that n-3 DG molecules have the advantage of incorporating at substantially higher levels than n-3 TG into an in vitro model of phospholipid membranes. We also observed that n-3 DG after parenteral administration in neonatal mice reaches the bloodstream more rapidly than n-3 TG. Using neonatal HI brain injury models in mice and rats, we found that n-3 DG emulsions provide superior neuroprotection than n-3 TG emulsions or TH in decreasing brain infarct size. Additionally, we found that n-3 DGs attenuate microgliosis and astrogliosis. Thus, n-3 DG emulsions are a superior, promising, and novel therapy for treating HIE.
Topics: Animals; Hypoxia-Ischemia, Brain; Animals, Newborn; Fatty Acids, Omega-3; Emulsions; Mice; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Mice, Inbred C57BL; Disease Models, Animal; Male; Brain
PubMed: 38761420
DOI: 10.1016/j.biopha.2024.116749 -
Reproduction (Cambridge, England) Jul 2024The endocrine disruptor, nonylphenol (NP) increases 20:4n-6 release in Sertoli cells via PKA/cPLA2 activation. Our data show that lipid metabolism could be a target of...
IN BRIEF
The endocrine disruptor, nonylphenol (NP) increases 20:4n-6 release in Sertoli cells via PKA/cPLA2 activation. Our data show that lipid metabolism could be a target of NP-induced abnormal reproductive outcomes.
ABSTRACT
Nonylphenol (NP), an endocrine-disrupting chemical, is an environmental contaminant, and many notorious effects on male fertility have been reported in animal models and wild-type species. Here, we evaluated the effects of NP in follicle-stimulating hormone (FSH) signal transduction pathways and lipid metabolism using an in vitro model of rat Sertoli cell (SC) primary culture. Results show that an acute (1 h) SC exposure to NP (10 µM) increased the intra- and extra-cellular concentrations of free fatty acids (FFAs), mainly arachidonic acid (20:4n-6). Phosphatidylinositol seemed to be the major phospholipid source of this 20:4n-6 release by activation of the protein kinase A (PKA)/cytoplasmic phospholipase A2 (cPLA2) pathway. NP also increased diacylglycerols (DAG) levels and the expression (mRNA) of cyclooxygenase 2 (Cox2) and prostaglandin E2 (PGE2) levels. It is noteworthy that accumulation of lipid droplets took place after 24 h NP exposition, which was prevented by both a PKA inhibitor and a PLA2 inhibitor. Like FSH, NP triggers the release of 20:4n-6, which is a substrate for PGE2 synthesis via PKA/PLA2 activation. In addition, NP induces the formation of DAG, which could be required as a cofactor of the PKC-mediated activation of the COX2 inflammatory pathway. Our findings suggest that NP alters lipid homeostasis in SCs by inducing the activation of pro-inflammatory pathways that may trigger adverse effects in testis physiology over time. Concomitantly, the SC enhances the acylation of surplus FFAs (including 20:4n-6) in neutral lipids as a protective mechanism to shield itself from lipotoxicity and pro-inflammatory signals.
Topics: Animals; Male; Sertoli Cells; Cyclic AMP-Dependent Protein Kinases; Phenols; Rats; Arachidonic Acid; Endocrine Disruptors; Phospholipases A2; Cells, Cultured; Lipid Metabolism; Signal Transduction; Follicle Stimulating Hormone
PubMed: 38758690
DOI: 10.1530/REP-23-0292 -
Nature Communications May 2024The regulated release of chemical messengers is crucial for cell-to-cell communication; abnormalities in which impact coordinated human body function. During vesicular...
The regulated release of chemical messengers is crucial for cell-to-cell communication; abnormalities in which impact coordinated human body function. During vesicular secretion, multiple SNARE complexes assemble at the release site, leading to fusion pore opening. How membrane fusion regulators act on heterogeneous SNARE populations to assemble fusion pores in a timely and synchronized manner, is unknown. Here, we demonstrate the role of SNARE chaperones Munc13-1 and Munc18-1 in rescuing individual nascent fusion pores from their diacylglycerol lipid-mediated inhibitory states. At the onset of membrane fusion, Munc13-1 clusters multiple SNARE complexes at the release site and synchronizes release events, while Munc18-1 stoichiometrically interacts with trans-SNARE complexes to enhance N- to C-terminal zippering. When both Munc proteins are present simultaneously, they differentially access dynamic trans-SNARE complexes to regulate pore properties. Overall, Munc proteins' direct action on fusion pore assembly indicates their role in controlling quantal size during vesicular secretion.
Topics: Munc18 Proteins; SNARE Proteins; Membrane Fusion; Nerve Tissue Proteins; Animals; Humans; Molecular Chaperones; Rats
PubMed: 38755165
DOI: 10.1038/s41467-024-46965-7 -
Colloids and Surfaces. B, Biointerfaces Jul 2024Lipid-based drug delivery systems offer the potential to enhance bioavailability, reduce dosing frequency, and improve patient adherence. In aqueous environment,...
Lipid-based drug delivery systems offer the potential to enhance bioavailability, reduce dosing frequency, and improve patient adherence. In aqueous environment, initially dry lipid depots take up water and form liquid crystalline phases. Variation of lipid composition, depot size and hydration-induced phase transitions will plausibly affect the diffusion in and out of the depot. Lipid depots of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) mixtures were hydrated for varying time durations in a phosphate-buffered saline (PBS) buffer and then analyzed with Karl Fischer titration, magnetic resonance imaging (MRI) and gravimetrically. Mathematical modeling of the swelling process using diffusion equations, was used to estimate the parameters of diffusion. Both composition of lipid mixture and depot size affect swelling kinetics… The diffusion parameters obtained in Karl Fischer titration and MRI (with temporal and spatial resolution respectively) are in good agreement. Remarkably, the MRI results show a gradient of water content within the depot even after the end of diffusion process. Apparently contradicting the first Fick's law in its classical form, these results find an explanation using the generalized Fick's law that considers the gradient of chemical potential rather than concentration as the driving force of diffusion.
Topics: Phosphatidylcholines; Glycine max; Kinetics; Diffusion; Water; Magnetic Resonance Imaging; Diglycerides
PubMed: 38754200
DOI: 10.1016/j.colsurfb.2024.113955