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Immunological Properties of Microbial Outer Membrane Proteins and Their Effects as Modulators of LPS Immunobiology
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Kathryn Nixdorff, Dagmar Schilling, Waltraud Ruiner
The lipoprotein from Escherichia coli with an apparent molecular mass of 7.2 kDa (Braun lipoprotein) has three fatty acids bound to glycerylcysteine in the N-terminal region of the polypeptide chain (21). As such, this protein represented a prime candidate for interaction with cells, and it was subsequently shown that the lipoprotein was indeed a very effective murine B lymphocyte mitogen when compared to the activity of LPS and purified protein derivative of tuberculin (6). The lipoprotein lost its mitogenic activity when the ester-linked fatty acids were removed by alkaline hydrolysis. Furthermore, it was not mitogenic for C3H/Tif mouse thymus cells but could stimulate B cells from LPS hyporesponsive C3H/HeJ mice. In the same study (6), it was shown that the lipoprotein could effect the differentiation of B cells to polyclonal IgM secretion.
Biology of microbes
Published in Philip A. Geis, Cosmetic Microbiology, 2006
Gram-negative walls. A Gram-negative bacterium has a thin peptidoglycan where the tetrapeptide coming off the NAM is directly linked to the one coming off a NAM on an adjacent strand of NAG–NAM polymer. The complexity of Gram-negative cell walls is astounding. They have outer membranes on the outsides of their thin peptidoglycan layers. Linking this outer membrane to the peptidoglycan is a compound called Braun’s lipoprotein. It is covalently linked to the peptidoglycan with its hydrophobic end stuck in the lipids of the underlying surface of the outer membrane (Figure 2.4).
Reversible cross-tolerance to platelet-activating factor signaling by bacterial toxins
Published in Platelets, 2021
Kandahalli Venkataranganayaka Abhilasha, Mosale Seetharam Sumanth, Anita Thyagarajan, Ravi Prakash Sahu, Kempaiah Kemparaju, Gopal Kedihithlu Marathe
Bacterial toxins are implicated in the pathogenesis of many inflammatory diseases like endotoxemia [1–4]. Such toxins are recognized by the Toll-like receptors (TLRs) [5,6]. Lipopolysaccharide (LPS), an abundant and widely employed endotoxin demonstrates its pro-inflammatory actions via TLR-4 [7] while lipoteichoic acid (LTA), bacterial lipoproteins such as Braun lipoprotein (BLP), and its synthetic analogue Pam3CSK4 signal through TLR-2 [8,9]. Activation of both TLR-4 and TLR-2 leads to signaling via mitogen-activated protein kinases (MAPKs) [10,11], and upregulation of nuclear factor kappa B (NF-κB) driven pro-inflammatory gene products such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-1, IL-6, IL-8, cyclooxygenase type 2 (COX-2), etc [2,12]. Accordingly, bacteria deficient in LPS are less toxic to mice [13].
Improving protein glycan coupling technology (PGCT) for glycoconjugate vaccine production
Published in Expert Review of Vaccines, 2020
Jennifer Mhairi Dow, Marta Mauri, Timothy Alexander Scott, Brendan William Wren
Depletion of the Braun’s lipoprotein gene generated a so called ‘leaky’ E. coli strain capable of releasing glycoconjugates in the supernatant, reducing purification complexity [104,105]. The risk of endotoxin contamination in the end product can be reduced by engineering strains with detoxified lipid A (unpublished work). Metabolic screening and metabolic engineering efforts can be deployed to further optimize and enhance glycoconjugate production yield [106–108]. More recently, PGCT has been performed using host bacteria other than E. coli. Examples to date include the use of Salmonella enterica sv. Paratyphi A [59] and Yersinia enterocolitica O9, which acts as a surrogate for Brucella abortus and Brucella suis due to the similarity with Y. enterocolitica’s O9 glycan repeat unit [109,137]. However, this requires the host to be relatively genetically tractable. Greater knowledge of glycosylation in bacteria continuously feeds into the PGCT toolbox, and the library of tailor-made ‘glycostrains’ continues to grow.