| 词条 | Lipoteichoic acid |
| 释义 |
Lipoteichoic acid (LTA) is a major constituent of the cell wall of gram-positive bacteria. These organisms have an inner (or cytoplasmic) membrane and, external to it, a thick (up to 80 nanometer) peptidoglycan layer. The structure of LTA varies between the different species of Gram-positive bacteria and may contain long chains of ribitol or glycerol phosphate. LTA is anchored to the cell membrane via a diacylglycerol.[1] It acts as regulator of autolytic wall enzymes (muramidases). It has antigenic properties being able to stimulate specific immune response. LTA may bind to target cells non-specifically through membrane phospholipids, or specifically to CD14 and to Toll-like receptors. Binding to TLR-2 has shown to induce NF-κB expression(a central transcription factor), elevating expression of both pro- and anti-apoptotic genes. Its activation also induces mitogen-activated protein kinases (MAPK) activation along with phosphoinositide 3-kinase activation. StudiesLTA's molecular structure has been found to have the strongest hydrophobic bonds of an entire bacteria. Said et al. showed that LTA causes an IL-10-dependent inhibition of CD4 T-cell expansion and function by up-regulating PD-1 levels on monocytes which leads to IL-10 production by monocytes after binding of PD-1 by PD-L.[2] References1. ^KP Talaro Foundations in Microbiology, McGraw Hill 6thEd. *Department of Oral Biology, Hebrew University-Hadassah Faculty of Dental Medicine, Ein-Kerem Campus, Jerusalem, Israel.2. ^Elias A. Said et al. 2009, PD-1 Induced IL10 Production by Monocytes Impairs T-cell Activation in a Reversible Fashion. Nature Medicine. 2010; 452-9. External links
2 : Organic acids|Cell biology |
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