dTDP-rhamnose provides L-rhamnose to the bridge-like structure between mycolyl arabinogalactan and peptidoglycan of the mycobacterial cell wall. dTDP-rhamnose is composed of glucose-1-phosphate and dTTP by four enzymes encoded by rmlA-D. To determine the region(s) of RmlC protein essential for its dTDP-4-keto-6-deoxyglucose epimerase activity, we overexpressed both whole (202 amino acids) and three different truncated (N-terminal 106 or 150 or C-terminal 97 amino acids) RmlC proteins of Mycobacterium tuberculosis. The RmlC enzyme activity in the soluble lysates of DELTArmlC E. coli strain SPHI874 (DE3 PlysS) expressing the wild type or truncated rmlC genes was initially analyzed by three sequential reactions from dTDP-glucose to dTDP-rhamnose in the presence of purified RmlB and RmlD. All three soluble lysates containing the truncated RmlC proteins showed no enzyme activity, while that containing the wild type RmlC was active. This wild type RmlC was then overexpressed and purified. The incubation of the purified RmlC enzyme so obtained with dTDP-4-keto-6-deoxyglucose resulted in the conversion of dTDP-4-keto-rhamnose. The results show that the truncated regions of the RmlC protein are important for the RmlC enzyme activity in M. tuberculosis.
Cell Wall ; Mycobacterium tuberculosis* ; Mycobacterium* ; Peptidoglycan ; Tuberculosis

Monofunctional biosynthetic peptidoglycan transglycosylase (MBPT) catalyzes the formation of the glycan chain in bacterial cell walls from peptidoglycan subunits: N-acetylglucosamine (NAG) and acetylmuramic acid (NAM). Bifunctional glycosyltransferases such as the penicillin binding protein (PBP) have peptidoglycan glycosyltransferase (PGT) on their C terminal end which links together the peptidoglycan subunits while transpeptidase (TP) on the N terminal end cross-links the peptide moieties on the NAM monosaccharide of the peptide subunits to create the bacterial cell wall. The singular function of MBPT resembles the C terminal end of PBP as it too contains and utilizes a similar PGT domain. In this article we analyzed the infectious and non infectious protein sequences of MBPT from 31 different strains of bacteria using a variety of bioinformatic tools. Motif analysis, dot-plot comparison, and phylogenetic analysis identified a number of significant differences between infectious and non-infectious protein sequences. In this paper we have made an attempt to explain, analyze and discuss these differences from an evolutionary perspective. The results of our sequence analysis may open the door for utilizing MBPT as a new target to fight a variety of infectious bacteria.
Bacteria ; Cell Wall ; Glycosyltransferases ; Muramic Acids ; Penicillin-Binding Proteins ; Penicillins ; Peptidoglycan ; Peptidoglycan Glycosyltransferase ; Sequence Analysis

Peptidoglycan (PG), the gram positive bacterial pathogen-associated molecular patterns (PAMP), is detected in a high proportion in macrophage-rich atheromatous regions, and expression of chemokine CXCL8, which triggers monocyte arrest on early atherosclerotic endothelium, is elevated in monocytes/macrophages in human atherosclerotic lesion. The aim of this study was to investigate whether PG induced CXCL8 expression in the cell type and to determine cellular signaling pathways involved in that process. Exposure of THP-1 cell, human monocyte/macrophage cell line, to PG not only enhanced CXCL8 release but also profoundly induced il8 gene transcription. PG-induced release of CXCL8 and induction of il8 gene transcription were blocked by OxPAPC, an inhibitor of TLR-2/4 and TLR4, but not by polymyxin B, an inhibitor of LPS. PG-mediated CXCL8 release was significantly attenuated by inhibitors of PI3K-Akt-mTOR pathways. PKC inhibitors, MAPK inhibitors, and ROS quenchers also significantly attenuated expression of CXCL8. The present study proposes that PG contributes to inflammatory reaction and progression of atherosclerosis by inducing CXCL8 expression in monocytes/macrophages, and that TLR-2, PI3K-Akt-mTOR, PKC, ROS, and MAPK are actively involved in the process.
Atherosclerosis ; Cell Line ; Endothelium ; Humans ; Interleukin-8 ; Monocytes ; Peptidoglycan* ; Polymyxin B

Nucleotide-binding domain 1 (Nod1) is a cytosolic receptor that is responsible for the recognition of a bacterial peptidoglycan motif containing meso-diaminophimelic acid. In this study, we sought to identify the role of Nod1 in host defense in vivo against pulmonary infection by multidrug resistant Acinetobacter baumannii. Wildtype (WT) and Nod1-deficient mice were intranasally infected with 3×107 CFU of A. baumannii and sacrificed at 1 and 3 days post-infection (dpi). Bacterial CFUs, cytokines production, histopathology, and mouse β-defensins (mBD) in the lungs of infected mice were evaluated. The production of cytokines in response to A. baumannii was also measured in WT and Nod1-deficient macrophages. The bacterial clearance in the lungs was not affected by Nod1 deficiency. Levels of IL-6, TNF-α, and IL-1β in the lung homogenates were comparable at days 1 and 3 between WT and Nod1-deficient mice, except the TNF-α level at day 3, which was higher in Nod1-deficient mice. There was no significant difference in lung pathology and expression of mBDs (mBD1, 2, 3, and 4) between WT and Nod1-deficient mice infected with A. baumannii. The production of IL-6, TNF-α, and NO by macrophages in response to A. baumannii was also comparable in WT and Nod1-deficient mice. Our results indicated that Nod1 does not play an important role in host immune responses against A. baumannii infection.
Acinetobacter baumannii* ; Acinetobacter* ; Animals ; Cytokines ; Cytosol ; Interleukin-6 ; Lung ; Macrophages ; Mice* ; Pathology ; Peptidoglycan

BACKGROUND: Systemic injection of peptidoglycan (PGN) special polymers, which are the primary structural components of most bacterial cell walls, leads to acute inflammation and pain behavior. This study was conducted to confirm that an intraplantar injection of PGN evoked hindpaw inflammation and hyperalgesia, and to evaluate the effects of bee venom (BV) pretreatment of an acupoint on PGN induced inflammation and hyperalgesia. METHODS: Inflammation and hyperalgesia were induced by injecting PGN into the plantar surface of one hindpaw of the rats. Inflammation and hyperalgesia were then evaluated by measuring the thickness of the hindpaw using a caliper and the paw withdrawal time (PWT) in response to noxious thermal stimulus (48degrees C hot water). In addition, spinal cord c-fos expression was quantitatively analyzed. The BV pretreatment was injected at the acupoint located 5 mm lower and 5 mm lateral to the anterior tubercle of the tibia in the hind limb. RESULTS: The PGN groups showed increased in paw thickness and spinal c-fos expression two hours after PGN injection, as well as decreased PWT in response to noxious thermal stimulus for each tested time. BV pretreatment of the acupoint was found to inhibit hindpaw thickness and led to a significant increase in PWT, but did not significantly inhibit spinal cord c-fos expression induced by PGN injection. CONCLUSIONS: These results indicated that BV pretreatment has both an anti-inflammatory and antinociceptive effect in PGN induced inflammatory pain, which suggests that peptidoglycan may be useful as an inflammatory agent for inflammatory pain models.
Acupuncture Points ; Animals ; Bee Venoms ; Bees ; Cell Wall ; Extremities ; Hyperalgesia ; Inflammation ; Peptidoglycan ; Polymers ; Rats ; Spinal Cord ; Tibia

Mast cells are primary mediators of allergic inflammation. Beta-1,3-glucan (BG) protects against infection and shock by activating immune cells. Activation of the BG receptor induces an increase in intracellular Ca2+, which may induce exocytosis. However, little is known about the precise mechanisms underlying BG activation of immune cells and the possible role of mitochondria in this process. The present study examined whether BG induced mast cell degranulation, and evaluated the role of calcium transients during mast cell activation. Our investigation focused on the role of the mitochondrial calcium uniporter (MCU) in BG-induced degranulation. Black mouse (C57) bone marrow-derived mast cells were stimulated with 0.5 microg/ml BG, 100 microg/ml peptidoglycan (PGN), or 10 microM A23187 (calcium ionophore), and dynamic changes in cytosolic and mitochondrial calcium and membrane potential were monitored. BG-induced mast cell degranulation occurred in a time-dependent manner, and was significantly reduced under calcium-free conditions. Ruthenium red, a mitochondrial Ca2+ uniporter blocker, significantly reduced mast cell degranulation induced by BG, PGN, and A23187. These results suggest that the mitochondrial Ca2+ uniporter has an important regulatory role in BG-induced mast cell degranulation.
Animals ; Calcimycin ; Calcium* ; Cytosol ; Exocytosis ; Inflammation ; Ion Transport* ; Mast Cells* ; Membrane Potentials ; Mice* ; Mitochondria ; Peptidoglycan ; Ruthenium Red ; Shock

Antibiotic resistance is a major global concern that primarily affects public health. Texiobactin is a newly discovered antibiotic produces by soil microbes isolated from natural environment. Drug is active against Gram-positive bacteria as it inhibits biosynthesis of peptidoglycan. Infection of methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae in mice elicits a good response reduce bacterial load. Although extensive efforts have been made to discover new antibiotics but results are still not satisfactory to meet the demands of public health. Recently it has been shown that the discovery of texiobactin by iChip will be a great stone mile to discover more antibiotics.
Animals ; Anti-Bacterial Agents ; Bacterial Load ; Drug Resistance, Microbial ; Gram-Positive Bacteria ; Methicillin-Resistant Staphylococcus aureus ; Mice ; Peptidoglycan ; Public Health ; Soil ; Streptococcus pneumoniae

Retinal pigment epithelium (RPE) constituting the outer blood-retina barrier plays an important role in ocular defense mechanism. Many studies reported that RPE participates in ongoing immune responses in the retina. However, the exact mechanism is still uncertain. Toll-like receptors (TLRs) participate in the recognition of pathogen-associated molecular patterns (PAMP), such as LPS, zymosan, lipoprotein, and dsRNA. The expression and function of TLRs in human RPE have not been established. In this study, we investigated TLRs expression in human fetal RPE and their recognition of PAMP to determine how human RPE participates in ocular defense mechanism against microbial component. RT-PCR and real time PCR revealed that TLR1 through 5 were constitutively expressed in human fetal RPE, and their expressions were slightly increased by LPS. We determined the TNF-alpha, IL-6, and IL-8 expression in human fetal RPE after treatment with LPS, zymosan, petidoglycan, or poly I:C. RT-PCR demonstrated that LPS and poly I:C treatment increased the production of TNF-alpha, IL-6, and IL-8 in human fetal RPE. LPS showed more potent effects on TNF-alpha and IL-8 production. Peptidoglycan and zymosan did not induce the production of TNF-alpha. CD14, the co-receptor of LPS was weakly expressed and functioned in recognizing LPS in human fetal RPE. These results suggest that human RPE may participate in ocular defense mechanism against microbial component through toll-like receptors.
Epithelial Cells* ; Humans* ; Interleukin-6 ; Interleukin-8 ; Lipoproteins ; Peptidoglycan ; Real-Time Polymerase Chain Reaction ; Retina ; Retinal Pigment Epithelium ; Retinaldehyde* ; Toll-Like Receptors* ; Tumor Necrosis Factor-alpha ; Zymosan

BACKGROUND: Defensin, a major family of antimicrobial peptides, is small cationic, cysteine rich peptides with wide range of antimicrobial activity against Gram negative and Gram positive bacteria, fungi, yeast, and virus. Expression of human defensin-2 is upregulated by bacteria, virus, fungus and pro-inflammatory cytokines. However, this peptide was found to be only bacteriostatic, but not bactericidal, against the Gram positive bacteria. OBJECTIVE: To evaluate human defensin-2 (hBD-2) expression after exposure of human skin keratinocytes to the cell wall component of Gram positive bacteria such as lipoteichoic acid (LTA) and peptidoglycan(PEN), and to compare quantitatively the amount of expression with that after their exposure to the cell wall component of Gram negative bacteria. METHODS: Expression of hBD-2 was measured by reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemistry(IHC). RESULTS: 1. In RT-PCR results, the amount of hBD-2 expression after exposure to LPS was larger than those of PEN and LTA at 6 and 12 hours (p=0.02). At 24 hours, hBD-2 expression showed a peak in PEN stimulated group (p=0.09). 2. In Western blot analysis, hBD-2 expressions, when treated with PEN and LTA, were stronger than that treated with LPS at 6 and 12 hours. 3. In IHC, hBD-2 was stained much stronger in LPS stimulated group than PEN or LTA stimulated groups at 12 hours. CONCLUSION: Our study demonstrated that exposure of human skin keratinocytes to the cell wall components of Gram positive bacteria such as LTA and PEN triggered production of hBD-2 in addition to the cell wall component of Gram negative bacteria such as LPS, however, the amounts of expression were relatively stronger in LPS treated group.
Bacteria ; Blotting, Western ; Cell Wall ; Cysteine ; Cytokines ; Fungi ; Gram-Negative Bacteria ; Gram-Positive Bacteria ; Humans* ; Keratinocytes ; Peptides ; Peptidoglycan* ; Polymerase Chain Reaction ; Reverse Transcription ; Skin ; Thiram ; Yeasts

OBJECTIVE: The aim of this study was to clarify whether stimulation of recombinant IL-17, TLR2 and TLR4 by their specific ligands induces the production of RANKL and IL-6 in the fibroblast-like synoviocytes (FLSs) from RA patients. METHODS: FLSs were isolated from RA synovial tissues and they were stimulated with the IL-17, TLR2 ligand bacterial peptidoglycan (PGN) and TLR4 ligand lipopolysaccharide (LPS). The RANKL levels were assessed by RT-PCR and western blotting. The expressions of IL-17, TLR2, TLR4, RANKL and IL-6 in the RA synovium were quantified by immunohistochemistry and these values were compared with the values obtained in the osteoarthritis synovium. The increased IL-6 production in the culture supernatants of the RA FLSs was quantified by sandwich ELISA. RESULTS: The mRNA and protein levels of RANKL and IL-6 increased in the RA FLSs stimulated with PGN, LPS and IL-17, or PGN plus IL-17 or LPS plus IL-17. The expressions of IL-17, TLR2, TLR4, RANKL and IL-6 were much higher in the RA synovium than those in the osteoarthritis (OA) synovium. CONCLUSION: We observed synergistic effects of TLR-2, TLR-4 and IL-17 upon the induction of RANKL. In conclusion, our data supports the previous evidence of an important role of TLR-2, TLR-4 and IL-17 in the pathogenesis of RA.
Blotting, Western ; Fibroblasts ; Humans ; Immunohistochemistry ; Interleukin-17 ; Interleukin-6 ; Ligands ; Osteoarthritis ; Peptidoglycan ; RNA, Messenger ; Synovial Membrane ; Toll-Like Receptor 2 ; Toll-Like Receptor 4 ; Toll-Like Receptors