Not Lipoteichoic Acid but Lipoproteins Appear to Be the Dominant Immunobiologically Active Compounds in Staphylococcus aureus

Abstract

Lipoteichoic acid (LTA) derived from Staphylococcus aureus is reported to be a ligand of TLR2. However, we previously demonstrated that LTA fraction prepared from bacterial cells contains lipoproteins, which activate cells via TLR2. In this study, we investigated the immunobiological activity of LTA fraction obtained from S. aureus wild-type strain, lipoprotein diacylglycerol transferase deletion (Δlgt) mutant, which lacks palmitate-labeled lipoproteins, and its complemented strain and evaluated the activity of LTA molecule. LTA fraction was prepared by butanol extraction of the bacteria followed by hydrophobic interaction chromatography. Although all LTA fractions activated cells through TLR2, the LTA from Δlgt mutant was 100-fold less potent than those of wild-type and complemented strains. However, no significant structural difference in LTA was observed in NMR spectra. Further, alanylation of LTA molecule showed no effect in immunobiological activity. These results showed that not LTA molecule but lipoproteins are dominant immunobiologically active TLR2 ligand in S. aureus.

Staphylococcus aureus lipoproteins trigger human corneal epithelial innate response through toll-like receptor-2

“…In addition to LTA, TLR2 is known to be a predominant receptor utilized by lipoproteins derived from various microorganisms, including both gram-negative bacteria, such as Borrelia burgdorferi, Escherichia coli, Neisseria gonorrhoea, and Porphyromonas gingivalis and Gram positive bacteria S. aureus [20]. Consistent with a recent reports showing that not LTA but lipoproteins are dominant, immunobiologically active TLR2 ligand in S. aureus [20,27], in the present study we showed that the lipoproteins isolated from S. aureus stimulate epithelial cells, leading to the activation of TLR-mediated MAPK and NF-kB signaling pathways, and expression of an array of molecules associated with innate immune response. Thus, we conclude that S. aureus lipoproteins are a major activator of TLR2 in HCECs.…”

“…Several S. aureus components including lipoteichoic acid (LTA) [25], peptidoglycan [26], and lipoproteins [20,27] were reported to be the ligands of TLR2. However, it is controversial whether LTA and peptidoglycan serve as PAMPs recognized by a cell surface TLR2 [27][28][29]. We showed previously that HCECs express abundant TLR2 but do not recognize LTA [17].…”

CD36: Implications in cardiovascular disease

“…Recently, there has been some controversy about the exact nature of the ligand on gram positive bacteria. Hoebe et al reported it to be lipoteichoic acid, but one group argues that the actual ligand is a lipoprotein that co-isolates with lipoteichoic acid, and that when bacteria are mutated such that the lipoprotein cannot be biosynthesized, the resulting lipoteichoic acid has only 1/100 of the activating properties as lipoprotein (Hashimoto, et al, 2006). Whether lipoprotein or lipoteichoic acid, macrophages from CD36 KO mice were less efficient at phagocytosis of gram positive Staphylococcus aureus, less able to clear infection, and more susceptible to abscess and death (Stuart, et al, 2005).…”

Synthesis of glycerol phosphate lipoteichoic acid in Staphylococcus aureus

“…Briefly, LTA was extracted from bacterial lysates, subjected to octyl Sepharose chromatography, and eluted with a linear gradient of 1-propanol [15-65% (vol/ vol)] in 50 mM sodium citrate (pH 4.7) (30)(31)(32). Large quantities of LTA could only be purified from S. aureus ANG513 cultures that had been grown in the presence of IPTG, but not from cultures grown without IPTG, as judged by immunoblot and phosphate determinations ( Fig.…”