scholarly journals Peptidoglycan structure of Enterococcus faecium expressing vancomycin resistance of the VanB type

1996 ◽  
Vol 313 (3) ◽  
pp. 711-715 ◽  
Author(s):  
Danièle BILLOT-KLEIN ◽  
David SHLAES ◽  
Duncan BRYANT ◽  
David BELL ◽  
Jean van HEIJENOORT ◽  
...  
Keyword(s):  
Cell Wall ◽  
Amino Acid ◽  
Enterococcus Faecium ◽  
Amino Acid Analysis ◽  
Vancomycin Resistance ◽  
Muramic Acid ◽  
Glycopeptide Antibiotics ◽  
Cross Bridge ◽  
Peptidoglycan Structure ◽  
The Cross

Resistance to glycopeptide antibiotics in enterococci is due to the synthesis of UDP-MurNAc-tetrapeptide-D-lactate (where Mur is muramic acid) replacing the normal UDP-MurNAc-pentapeptide precursor. The peptidoglycan structures of an inducible VanB-type glycopeptide-resistant Enterococcus faecium, D366, and its constitutively resistant derivative, MT9, were determined. Using HPLC, 17 muropeptides were identified and were present regardless of whether resistance was expressed or not. The structures of 15 muropeptides were determined using MS and amino acid analysis. The cross-bridge between D-alanine and L-lysine consisted of one asparagine. No monomer pentapeptide or tetrapeptide-D-lactate could be identified. These results obtained with D366 (non-induced) and MT9 indicate that, in the absence of vancomycin, the cell wall synthetic machinery of E. faecium can process the lactate-containing precursor as efficiently as the normal pentapeptide. In contrast, the presence of subinhbitory inducing concentrations of vancomycin interfered with the synthesis of oligomers.

scholarly journals FmhA and FmhC of Staphylococcus aureus incorporate serine residues into peptidoglycan cross-bridges

2020 ◽  
Vol 295 (39) ◽  
pp. 13664-13676 ◽  
Author(s):  
Stephanie Willing ◽  
Emma Dyer ◽  
Olaf Schneewind ◽  
Dominique Missiakas
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Proteins ◽  
Penicillin Binding Proteins ◽  
Daughter Cells ◽  
Cross Bridge ◽  
Resistant Strains ◽  
The Cross ◽  
Cross Bridges ◽  
Adjacent Wall

Staphylococcal peptidoglycan is characterized by pentaglycine cross-bridges that are cross-linked between adjacent wall peptides by penicillin-binding proteins to confer robustness and flexibility. In Staphylococcus aureus, pentaglycine cross-bridges are synthesized by three proteins: FemX adds the first glycine, and the homodimers FemA and FemB sequentially add two Gly-Gly dipeptides. Occasionally, serine residues are also incorporated into the cross-bridges by enzymes that have heretofore not been identified. Here, we show that the FemA/FemB homologues FmhA and FmhC pair with FemA and FemB to incorporate Gly-Ser dipeptides into cross-bridges and to confer resistance to lysostaphin, a secreted bacteriocin that cleaves the pentaglycine cross-bridge. FmhA incorporates serine residues at positions 3 and 5 of the cross-bridge. In contrast, FmhC incorporates a single serine at position 5. Serine incorporation also lowers resistance toward oxacillin, an antibiotic that targets penicillin-binding proteins, in both methicillin-sensitive and methicillin-resistant strains of S. aureus. FmhC is encoded by a gene immediately adjacent to lytN, which specifies a hydrolase that cleaves the bond between the fifth glycine of cross-bridges and the alanine of the adjacent stem peptide. In this manner, LytN facilitates the separation of daughter cells. Cell wall damage induced upon lytN overexpression can be alleviated by overexpression of fmhC. Together, these observations suggest that FmhA and FmhC generate peptidoglycan cross-bridges with unique serine patterns that provide protection from endogenous murein hydrolases governing cell division and from bacteriocins produced by microbial competitors.

scholarly journals Inhibition of Staphylococcus aureus Cell Wall Biosynthesis by Desleucyl-Oritavancin: a Quantitative Peptidoglycan Composition Analysis by Mass Spectrometry

2017 ◽  
Vol 199 (15) ◽  
Author(s):  
James D. Chang ◽  
Erin E. Foster ◽  
Aanchal N. Thadani ◽  
Alejandro J. Ramirez ◽  
Sung Joon Kim
Keyword(s):  
Mass Spectrometry ◽  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Binding Site ◽  
Mode Of Action ◽  
Composition Analysis ◽  
Edman Degradation ◽  
Glycopeptide Antibiotics ◽  
Content Type ◽  
The Cross

ABSTRACT Oritavancin is a lipoglycopeptide antibiotic that exhibits potent activities against vancomycin-resistant Gram-positive pathogens. Oritavancin differs from vancomycin by a hydrophobic side chain attached to the drug disaccharide, which forms a secondary binding site to enable oritavancin binding to the cross-linked peptidoglycan in the cell wall. The mode of action of secondary binding site was investigated by measuring the changes in the peptidoglycan composition of Staphylococcus aureus grown in the presence of desleucyl-oritavancin at subinhibitory concentration using liquid chromatography-mass spectrometry (LC-MS). Desleucyl-oritavancin is an Edman degradation product of oritavancin that exhibits potent antibacterial activities despite the damaged d-Ala–d-Ala binding site due to its functional secondary binding site. Accurate quantitative peptidoglycan composition analysis based on 83 muropeptide ions determined that cell walls of S. aureus grown in the presence of desleucyl-oritavancin showed a reduction of peptidoglycan cross-linking, increased muropeptides with a tetrapeptide-stem structure, decreased O-acetylation of MurNAc, and increased N-deacetylation of GlcNAc. The changes in peptidoglycan composition suggest that desleucyl-oritavancin targets the peptidoglycan template to induce cell wall disorder and interferes with cell wall maturation. IMPORTANCE Oritavancin is a lipoglycopeptide antibiotic with a secondary binding site that targets the cross-linked peptidoglycan bridge structure in the cell wall. Even after the loss of its primary d-Ala–d-Ala binding site through Edman degradation, desleucyl-oritavancin exhibits potent antimicrobial activities through its still-functioning secondary binding site. In this study, we characterized the mode of action for desleucyl-oritavancin's secondary binding site using LC-MS. Peptidoglycan composition analysis of desleucyl-oritavancin-treated S. aureus was performed by determining the relative abundances of 83 muropeptide ions matched from a precalculated library through integrating extracted ion chromatograms. Our work highlights the use of quantitative peptidoglycan composition analysis by LC-MS to provide insights into the mode of action of glycopeptide antibiotics.

Peptidoglycan structure in cell walls of parental and filamentous Streptococcus cremoris HP

1974 ◽  
Vol 20 (7) ◽  
pp. 905-913 ◽  
Author(s):  
K. G. Johnson ◽  
I. J. McDonald
Keyword(s):  
Cell Wall ◽  
Glutamic Acid ◽  
Cell Walls ◽  
Free Amino ◽  
Muramic Acid ◽  
Chemical Analyses ◽  
Amino Groups ◽  
Streptococcus Cremoris ◽  
Peptidoglycan Structure ◽  
Filamentous Cell

Cell walls were prepared from parental and filamentous cells of Streptococcus cremoris HP. In addition to aspartic acid, glutamic acid, alanine, and lysine in a 1:2:3:1 ratio, such preparations contained hot formamide-extractable material composed of glucosamine, glucosa-mine-6-phosphate, glucose, galactose, and rhamnose. Parental and filamentous cell walls contained, respectively, 210 and 225 disaccharide units per milligram. The ratio of muramic acid: peptide subunits was about 1.3 for both preparations.Enzymic and chemical analyses revealed that glycan strands are incompletely substituted, peptide cross-bridging is not mediated by D-alanyl-L-alanyl linkages, peptide subunits are linked together to form large moieties, and no significant differences in peptidoglycan structure exist between parental and filamentous cell walls.Analysis by dinitrophenylation techniques disclosed the presence of significant quantities of glucosamine and muramic acid residues with free amino groups in the peptidoglycans of both cell wall preparations. Conversion of such groups by dinitrophenylation or N-acetylation greatly enhanced the response of cell walls to lysozyme digestion.

scholarly journals Detection of clonally related vanB2-containing Enterococcus faecium strains in two Spanish hospitals

2006 ◽  
Vol 55 (9) ◽  
pp. 1237-1243 ◽  
Author(s):  
Carmen Torres ◽  
Susanna Escobar ◽  
Aránzazu Portillo ◽  
Luis Torres ◽  
Antonio Rezusta ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gene Cluster ◽  
Intergenic Region ◽  
Enterococcus Faecium ◽  
Resistance Mechanism ◽  
Vancomycin Resistance ◽  
Pfge Pattern ◽  
Genetic Environment ◽  
Vancomycin Resistant

The aim of this study was to characterize the resistance mechanism in four clinical and five intestinal vancomycin-resistant Enterococcus faecium strains with VanB phenotype recovered from unrelated patients confined in two Spanish hospitals and to determine their clonal relationships. MIC values for vancomycin and teicoplanin were 16–32 and 0.5 μg ml−1, respectively. The mechanism of vancomycin resistance, as well as the genetic environment of the implicated gene, was analysed by PCR and sequencing. The vanB2 gene was detected in all nine E. faecium strains and the intergenic vanS B–Y B region showed the characteristic mutations of the vanB2 subtype. Two possibly related PFGE patterns, A (seven strains) and B (two strains), were distinguished among these enterococci. The vanX B–ORFC intergenic region was amplified in the nine strains and two amino acid changes were detected in the protein encoded by the vanX B gene in strains of pattern A with respect to those of pattern B. The vanB2 gene cluster was integrated into Tn5382 in all nine strains, being pbp5 gene-linked to this transposon. The ant(6′)-Ia, aph(3′)-IIIa and erm(B) genes were also detected in all of the strains. Both isolates with PFGE pattern B contained the esp gene. In summary, vanB2-containing E. faecium strains with indistinguishable PFGE patterns were recovered from seven patients from two Spanish hospitals.

scholarly journals Die Aminosäuresequenz des Serin und Asparaginsäure enthaltenden Mureins von Bifidobacterium bifidum Orla Jensen/ The amino acid sequence of the serin and aspartic acid containing mureins of Bifidobacterium bifidum ORLA JENSEN

1970 ◽  
Vol 25 (11) ◽  
pp. 1294-1301 ◽  
Author(s):  
Dieter Koch ◽  
Karl Heinz Schleifer ◽  
Otto Kandler
Keyword(s):  
Cell Wall ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Cell Walls ◽  
Teichoic Acid ◽  
Bifidobacterium Bifidum ◽  
Muramic Acid ◽  
Partial Acid Hydrolysis

Cell walls of Bifidobacterium bifidum var. pennsylvanicus were isolated. The polysaccharide consisted of glucose, galactose and rhamnose. Teichoic acid was not present. The murein (peptidoglycan) contained MurNAc, GlcNH2NAc, ᴅ-Glu, Ala. ʟ-Ser, ᴅ-Asp and L-Orn in a ratio of about 1 : 1 : 1 : 2 : 1 : 1 : 1. In one batch a high amount of ʟ-glutamic acid was found. It was not a constituent of the murein since it remained in the lysozyme insensitive residue.The amino acid sequence of the murein was determined by analyzing the oligopeptides arising during partial acid hydrolysis. It was shown that the peptide subunits attached to the muramic acid are the same as in many other mureins: ʟ-Ala-ᴅ-Glu-ʟ-Orn-D-Ala. The interpeptide bridge consisted of β-ᴅ-aspartyl-ʟ-serine. Since about 35% of aspartic acid and 6% of ornithine are N-terminal in the cell wall, it was assumed that only 60% of the peptide subunits are cross-linked. 4 other strains of B. bifidum proved to contain the same type of murein. While all other strains of other species of Bifidobacterium investigated contained other types of murein, it seems likely that the Orn-Ser-Asp type of the murein is typical of B. bifidum.

An ESR study of the peroxidase reaction catalyzed by human methaemoglobin and methaemoglobin-haptoglobin complex

1991 ◽  
Vol 56 (4) ◽  
pp. 923-932
Author(s):  
Jana Stejskalová ◽  
Pavel Stopka ◽  
Zdeněk Pavlíček
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Peroxidase Activity ◽  
Amino Acid Analysis ◽  
Superoxide Radical ◽  
Esr Spectra ◽  
The Other ◽  
Delocalized Electron

The ESR spectra of peroxidase systems of methaemoglobin-ascorbic acid-hydrogen peroxide and methaemoglobin-haptoglobin complex-ascorbic acid-hydrogen peroxide have been measured in the acetate buffer of pH 4.5. For the system with methaemoglobin an asymmetrical signal with g ~ 2 has been observed which is interpreted as the perpendicular region of anisotropic spectrum of superoxide radical. On the other hand, for the system with methaemoglobin-haptoglobin complex the observed signal with g ~ 2 is symmetrical and is interpreted as a signal of delocalized electron. After realization of three repeatedly induced peroxidase processes the ESR signal of the perpendicular part of anisotropic spectrum of superoxide radical is distinctly diminished, whereas the signal of delocalized electron remains practically unchanged. An amino acid analysis of methaemoglobin along with results of the ESR measurements make it possible to derive a hypothesis about the role of haptoglobin in increasing of the peroxidase activity of methaemoglobin.

Sign in / Sign up

Export Citation Format

Share Document