TY - JOUR A1 - Peters, Simon A1 - Fohmann, Ingo A1 - Rudel, Thomas A1 - Schubert-Unkmeir, Alexandra T1 - A Comprehensive Review on the Interplay between Neisseria spp. and Host Sphingolipid Metabolites JF - Cells N2 - Sphingolipids represent a class of structural related lipids involved in membrane biology and various cellular processes including cell growth, apoptosis, inflammation and migration. Over the past decade, sphingolipids have become the focus of intensive studies regarding their involvement in infectious diseases. Pathogens can manipulate the sphingolipid metabolism resulting in cell membrane reorganization and receptor recruitment to facilitate their entry. They may recruit specific host sphingolipid metabolites to establish a favorable niche for intracellular survival and proliferation. In contrast, some sphingolipid metabolites can also act as a first line defense against bacteria based on their antimicrobial activity. In this review, we will focus on the strategies employed by pathogenic Neisseria spp. to modulate the sphingolipid metabolism and hijack the sphingolipid balance in the host to promote cellular colonization, invasion and intracellular survival. Novel techniques and innovative approaches will be highlighted that allow imaging of sphingolipid derivatives in the host cell as well as in the pathogen. KW - sphingolipids KW - host–pathogen interaction KW - Neisseria meningitidis KW - Neisseria gonorrhoeae Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-250203 SN - 2073-4409 VL - 10 IS - 11 ER - TY - THES A1 - Kaiser, Lena Franziska T1 - Wirkmechanismus von Sphingolipiden und Sphingosin gegen mikrobielle Erreger T1 - Mechanism of the bactericidal effect of sphingolipids and sphingosine against microbial pathogens N2 - Die zunehmende Antibiotikaresistenz vieler Krankheitserreger ist ein weltweites Problem, welches zu einem klinischen Bedarf an neuen antimikrobiellen Substanzen führt. Sphingolipide einschließlich Ceramide stellen eine vielfältige Gruppe strukturverwandter Lipide dar und bestehen aus einem Sphingosin-Grundgerüst, welches mit einer Fettsäure verbunden ist. Sowohl das Sphingosin-Grundgerüst allein als auch Sphingolipide zeigen eine antibakterielle Wirkung gegenüber einer Vielzahl pathogener Mikroorganismen. Die Intensität der Hemmung hängt von der Sphingolipidstruktur und dem Mikroorganismus ab. Neuere Studien konnten zeigen, dass Sphingosin, Ceramide und Ceramid-Analoga in N. meningitidis aufgenommen werden und eine bakteriostatische oder bakterizide Wirkung zeigen. Jedoch ist die antibakterielle Wirkungsweise noch nicht genau bekannt. Um mehr über den Wirkmechanismus zu erfahren haben wir die ultrastrukturellen Veränderungen von N. meningitidis nach Inkubation mit azido-funktionalisierten Sphingolipiden mit elektronenmikroskopischen Verfahren (transmissionselektronenmikroskopische und rasterelektronenmikroskopische Aufnahmen) untersucht. Mittels korrelativer Licht- und Elektronenmikroskopie (CLEM) konnten wir die azido-funktionalisierten Sphingolipide nach Aufnahme in N. meningitidis lokalisieren. Zum Anfärben der funktionalisierten Sphingolipide wurde die kupferfreie Azid-Alkin-Cyccloaddition verwendet. N2 - The increasing antibiotic resistance of many pathogens is a worldwide problem that leads to a clinical need of new anti-microbial compounds. Sphingolipids, including ceramides, represent a diverse group of structurally related lipids and are composed of a sphingosine backbone coupled to a fatty acid. Solely the sphingosine backbone as well as the sphingolipids show antibacterial activity against a wide range of pathogenic microorganisms. The rate of inhibition depends on the sphingolipid structure and the microbial strain. Recent studies revealed the uptake of sphingosine, ceramides and ceramide analogues by N. meningitidis and a bacteriostatic or bactericidal effect. However, the mechanism of the bactericidal effect is still unknown. To elucidate the antibacterial mechanism, we studied the ultrastructural changes after incubation of N. meningitidis with azido-modified sphingolipids by using electron microscopy techniques (transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Due to correlative light-electron microscopy (CLEM) we were able to localize the azido-modified sphingolipids after incorporation in N. meningitidis. Copper-free azide-alkyne cycloaddition was used to stain the azido-modified sphingolipids. KW - Neisseria meningitidis KW - Sphingolipide KW - Sphingosin KW - Antimikrobieller Wirkstoff KW - Mikroskopie KW - sphingolipids Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218970 ER - TY - JOUR A1 - Schlegel, Jan A1 - Peters, Simon A1 - Doose, Sören A1 - Schubert-Unkmeir, Alexandra A1 - Sauer, Markus T1 - Super-resolution microscopy reveals local accumulation of plasma membrane gangliosides at Neisseria meningitidis Invasion Sites JF - Frontiers in Cell and Developmental Biology N2 - Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for epidemic meningitis and sepsis worldwide. A critical step in the development of meningitis is the interaction of bacteria with cells forming the blood-cerebrospinal fluid barrier, which requires tight adhesion of the pathogen to highly specialized brain endothelial cells. Two endothelial receptors, CD147 and the β2-adrenergic receptor, have been found to be sequentially recruited by meningococci involving the interaction with type IV pilus. Despite the identification of cellular key players in bacterial adhesion the detailed mechanism of invasion is still poorly understood. Here, we investigated cellular dynamics and mobility of the type IV pilus receptor CD147 upon treatment with pili enriched fractions and specific antibodies directed against two extracellular Ig-like domains in living human brain microvascular endothelial cells. Modulation of CD147 mobility after ligand binding revealed by single-molecule tracking experiments demonstrates receptor activation and indicates plasma membrane rearrangements. Exploiting the binding of Shiga (STxB) and Cholera toxin B (CTxB) subunits to the two native plasma membrane sphingolipids globotriaosylceramide (Gb3) and raft-associated monosialotetrahexosylganglioside GM1, respectively, we investigated their involvement in bacterial invasion by super-resolution microscopy. Structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM) unraveled accumulation and coating of meningococci with GM1 upon cellular uptake. Blocking of CTxB binding sites did not impair bacterial adhesion but dramatically reduced bacterial invasion efficiency. In addition, cell cycle arrest in G1 phase induced by serum starvation led to an overall increase of GM1 molecules in the plasma membrane and consequently also in bacterial invasion efficiency. Our results will help to understand downstream signaling events after initial type IV pilus-host cell interactions and thus have general impact on the development of new therapeutics targeting key molecules involved in infection. KW - Neisseria meningitidis KW - sphingolipids KW - gangliosides and lipid rafts KW - super-resolution microscopy KW - single-molecule tracking Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201639 VL - 7 IS - 194 ER -