The human LL-37 peptide exerts antimicrobial activity against Legionella micdadei interacting with membrane phospholipids
Legionella micdadei is responsible for community- or nosocomial-acquired pneumonia as well as the influenza-like illness Pontiac fever. The aim of this study was to investigate the ability of L. micdadei to utilize extracellular choline for phosphatidylcholine (PC) synthesis and its consequences for the phospholipid composition of its membrane system and the interaction with the human LL-37 peptide. Comparative analysis of the PC content using isotopic labeling revealed that in presence of exogenous choline 98% of the total PC was synthesized via the Pcs pathway while the remaining 2% were generated via the PE-methylation (PmtA) pathway. PC species were to a greater extent defined by the Pcs pathway in the outer membrane than in the inner membrane. While no major changes in the bacterial lipid content were observed using 31P NMR, indication for utilization of longer acyl chains and slight increase of PG in response to choline addition was observed by a top-down lipidomics screen. The LL-37 peptide inhibited L. micdadei growth in a dose-dependent manner. Bacteria cultured with exogenous choline were more sensitive to the LL-37 peptide when compared to the standard culture condition. Our biophysical investigations show that the peptide perturbs bacterial-derived phospholipid monolayers and this interaction is dependent on the molar portion of PC. This interaction is responsible for the observed changes in the anti-L. micdadei activity of the LL-37 peptide.
Palusińska-Szysz, M. et al., The human LL-37 peptide exerts antimicrobial activity against Legionella micdadei interacting with membrane phospholipids, Biochim Biophys Acta Mol Cell Biol Lipids (2022)doi: 10.1016/j.bbalip.2022.159138
Pseudomonas species infect a variety of organisms, including mammals and plants. Mammalian pathogens of the Pseudomonas family modify their lipid A during host entry to evade immune responses and to create an effective barrier against different environments, for example by removal of primary acyl chains, addition of phosphoethanolamine (P-EtN) to primary phosphates, and hydroxylation of secondary acyl chains. For Pseudomonas syringae pv. phaseolicola (Pph) 1448A, an economically important pathogen of beans, we observed similar lipid A modifications by mass spectrometric analysis. Therefore, we investigated predicted proteomes of various plant-associated Pseudomonas spp. for putative lipid A-modifying proteins using the well-studied mammalian pathogen Pseudomonas aeruginosa as a reference. We generated isogenic mutant strains of candidate genes and analyzed their lipid A. We show that the function of PagL, LpxO, and EptA is generally conserved in Pph 1448A. PagL-mediated de-acylation occurs at the distal glucosamine, whereas LpxO hydroxylates the secondary acyl chain on the distal glucosamine. The addition of P-EtN catalyzed by EptA occurs at both phosphates of lipid A. Our study characterizes lipid A modifications in vitro and provides a useful set of mutant strains relevant for further functional studies on lipid A modifications in Pph 1448A.
Gerster, T. et al., Remodeling of Lipid A in Pseudomonas syringae pv. phaseolicola In Vitro, International Journal of Molecular Sciences (2022)doi:10.3390/ijms23041996
Lysosome-associated membrane glycoprotein 3 (LAMP3) is a type I transmembrane protein of the LAMP protein family with a cell-type-specific expression in alveolar type II cells in mice and hitherto unknown function. In type II pneumocytes, LAMP3 is localized in lamellar bodies, secretory organelles releasing pulmonary surfactant into the extracellular space to lower surface tension at the air/liquid interface. The physiological function of LAMP3, however, remains enigmatic. We generated Lamp3 knockout mice by CRISPR/Cas9. LAMP3 deficient mice are viable with an average life span and display regular lung function under basal conditions. The levels of a major hydrophobic protein component of pulmonary surfactant, SP-C, are strongly increased in the lung of Lamp3 knockout mice, and the lipid composition of the bronchoalveolar lavage shows mild but significant changes, resulting in alterations in surfactant functionality. In ovalbumin-induced experimental allergic asthma, the changes in lipid composition are aggravated, and LAMP3-deficient mice exert an increased airway resistance. Our data suggest a critical role of LAMP3 in the regulation of pulmonary surfactant homeostasis and normal lung function.
Lunding, L. P. et al., LAMP3 deficiency affects surfactant homeostasis in mice, PLoS Genetics (2021)doi:10.1371/journal.pgen.1009619 Supplementary Material:
- LipidXplorer Output, MFQLs and configuration: LAMP3-Supplement.zip
We introduce Goslin, a polyglot grammar for common lipid shorthand nomenclatures based on the LIPID MAPS nomenclature and the shorthand nomenclature established by Liebisch and co-authors and used by LipidHome and SwissLipids. Goslin was designed to address the following pressing issues in the lipidomics field: 1) to simplify the implementation of lipid name handling for developers of mass spectrometry-based lipidomics tools; 2) to offer a tool that unifies and normalizes the main existing lipid name dialects enabling a lipidomics analysis in a high-throughput fashion and 3) to provide a consistent mapping from lipid shorthand names to lipid building blocks and structural properties. We provide implementations of Goslin in four major programming languages, namely C++, Java, Python 3, and R to kick-start adoption and integration. Further, we set up a web service for users to work with Goslin directly. All implementations are available free of charge under a permissive open source license.