User:Immcarle196/Pathogen-associated molecular pattern
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Pathogen-associated molecular pattern
[edit]Lead
[edit]Pathogen-associated molecular patterns (PAMPs) are small molecular motifs conserved within a class of microbes. These PAMPs are usually encode parts of the organism vital to survival, thus hard to modify, and are not present in the host[1]. They are recognized by toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) in both plants and animals. A vast array of different types of molecules can serve as PAMPs, including glycans and glycoconjugates.
Common PAMPs
[edit]Bacterial lipopolysaccharides (LPSs), also known as endotoxins, are found on the outer cell membranes of gram-negative bacteria, are considered to be the prototypical class of PAMPs. The lipid portion of LPS, lipid-A, is the diglycolamine backbone with multiple acyl chains and is usually the conserved structural motif that is recognized by TLR4, particularly the TLR-MD2 complex[2][3], Microbes can nuse 2 strategies to avoid detection, either masking of Lipid A to prevent immune recognition or directing LPS toward an immunomodulatory receptor[2].
Flagellin is also another PAMP that is recognized via the constant domain, D1 by TLR5[4]. Despite being a protein, its N- and C- terminal ends are highly conserved, due to its necessity for function of flagella[5]. Lipoteichoic acid (LTA) from gram-positive bacteria, peptidoglycan (PG), bacterial lipoproteins (sBLP)[3], a phenol soluble factor from Staphylococcus epidermidis, LPS from porphyromonas gingivitis, and glycosylphosohotidylinotol lipiosd from trypanosoma cruzi, and a component of yeast walls called zymosan, are all recognized by a heterodimer of TLR2 and TLR1 or TLR6[5]. However, LTAs result in a weaker pro-inflammatory response compared to lipopeptides, as they are only recognized by TLR2 instead of the heterodimer[2]. Double-stranded RNA (dsRNA), a universal viral PAMP, is recognized by TLR3. CpG motifs, found in bacterial DNA, need to be internalized to be recognized by TLR9. Viral glycoproteins, as seen in the viral-envelope, as well as fungal PAMPS on the cell surface or fungi are recognized by TLR2 and TLR4[5].
History
[edit]First introduced by Janeway in 1989, PAMP was used to describe microbial components that would be considered foreign in a multicellular host[2]. The term "PAMP" has been criticized on the grounds that most microbes, not only pathogens, express the molecules detected; the term microbe-associated molecular pattern (MAMP), has therefore been proposed. A virulence signal capable of binding to a pathogen receptor, in combination with a MAMP, has been proposed as one way to constitute a (pathogen-specific) PAMP. Plant immunology frequently treats the terms "PAMP" and "MAMP" interchangeably, considering their recognition to be the first step in plant immunity, PTI (PAMP-triggered immunity), a relatively weak immune response that occurs when the host plant does not also recognize pathogenic effectors that damage it or modulate its immune response.
References
[edit]- ^ Tang, Daolin; Kang, Rui; Coyne, Carolyn B.; Zeh, Herbert J.; Lotze, Michael T. (2012-09). "PAMPs and DAMPs: signal 0s that spur autophagy and immunity". Immunological Reviews. 249 (1): 158–175. doi:10.1111/j.1600-065X.2012.01146.x. PMC 3662247. PMID 22889221.
{{cite journal}}: Check date values in:|date=(help)CS1 maint: PMC format (link) - ^ a b c d Silva-Gomes, Sandro; Decout, Alexiane; Nigou, Jérôme (2015), Parnham, Michael (ed.), "Pathogen-Associated Molecular Patterns (PAMPs)", Encyclopedia of Inflammatory Diseases, Basel: Springer, pp. 1–16, doi:10.1007/978-3-0348-0620-6_35-1, ISBN 978-3-0348-0620-6, retrieved 2023-03-09
- ^ a b Ahmad-Nejad, Parviz; Häcker, Hans; Rutz, Mark; Bauer, Stefan; Vabulas, Ramunas M.; Wagner, Hermann (June 20, 2002). "Bacterial CpG-DNA and lipopolysaccharides activate Toll-like receptors at distinct cellular compartments". European Journal of Immunology. 32 (7): 1819--2094 – via Wiley Online.
- ^ Akira, Shizuo; Uematsu, Satoshi; Takeuchi, Osamu (2006-02-24). "Pathogen Recognition and Innate Immunity". Cell. 124 (4): 783–801. doi:10.1016/j.cell.2006.02.015. ISSN 0092-8674.
- ^ a b c Janeway, Charles A.; Medzhitov, Ruslan (2002-04). "Innate Immune Recognition". Annual Review of Immunology. 20 (1): 197–216. doi:10.1146/annurev.immunol.20.083001.084359. ISSN 0732-0582.
{{cite journal}}: Check date values in:|date=(help)