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At least 487 records · Page 27Linked to original sources
PubMed1995

Structure of peptidoglycan from Thermus thermophilus HB8.

The composition and structure of peptidoglycan (murein) extracted from the extreme thermophilic eubacterium Thermus thermophilus HB8 are presented. The structure of 29 muropeptides, accounting for more than 85% of total murein, is reported. The basic monomeric subunit consists of N-acetylglucosamine-N-acetylmuramic acid-L-Ala-D-Glu-L-Orn-D-Ala-D-Ala, acylated at the delta-NH2 group of Orn by a Gly-Gly dipeptide. In a significant proportion (about 23%) of total muropeptides, the N-terminal Gly is substituted by a residue of phenylacetic acid. This is the first time phenylacetic acid is described as a component of bacterial murein. Possible implications for murein physiology and biosynthesis are discussed. Murein cross-linking is mediated by D-Ala-Gly-Gly peptide cross-bridges. Glycan chains are apparently terminated by (1-->6) anhydro N-acetylmuramic acid residues. Neither reducing sugars nor murein-bound macromolecules were detected. Murein from T. thermophilus presents an intermediate complexity between those of gram-positive and gram-negative organisms. The murein composition and peptide cross-bridges of T. thermophilus are typical for a gram-positive bacterium. However, the murein content, degree of cross-linkage, and glycan chain length for T. thermophilus are closer to those for gram-negative organisms and could explain the gram-negative character of Thermus spp.

Acetylglucosamine↗
PubMed1975

Coordinated incorporation of nascent peptidoglycan and teichoic acid into pneumococcal cell walls and conservation of peptidoglycan during growth.

Choline-containing pneumococcal cell wals are sensitive to autolysin, whereas ethanolamine-containing walls are not. Bacteria were labeled with radioactive peptidoglycan precursors while growing either in choline- or in ethanolaminecontaining media. Subsequently, the labeled cells were allowed to grow for four to five generations in nonradioactive medium supplemented with the alternative amino alcohol source (i.e. cells labeled in choline medium yields ethanolamine; cells labeled in ethanolamine medium yields choline). The autolysin sensitivity of the isotope label in cell walls prepared from such bacteria indicates that nascent peptidoglycan and teichoic acid units that are synthesized at the same time are attached to one another, incorporated into the cell surface at the cellular equator, and remain conserved during growth the division of the bacteria.

Alanine↗
PubMed1998

Structures of biologically active muramyl peptides from peptidoglycan of Streptococcus sanguis.

The structures of major muramyl peptides derived from peptidoglycan of the oral pathogen Streptococcus sanguis were determined and the biological activity of the peptides was tested in vitro on human monocytes. The muramyl peptides, produced by muramidase digestion of the purified peptidoglycan, were separated by reversed-phase high-performance liquid chromatography, either in their native form or after reduction with sodium borohydride. Chemical structures of the peptides were elucidated by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, amino acid analysis, post-source decay analysis and Edman sequencing. The study revealed two distinct monomers: N-acetylglucosaminyl-N-acetylmuramyl-Ala-iGln-Lys(Ala-Ala) (1), where the Ala-Ala is connected to the epsilon-amino group of lysine, and N-acetylglucosaminyl-N-acetylmuramyl-Ala-iGln-Lys(Ala-Ala)-Ala-Ala (2), where an additional dialanyl residue is attached to the lysine alpha-carboxyl group. Two sets of higher oligomers (di-, tri- and tetramers), related structurally to monomers 1 or 2 were also detected. In these oligomers, the monomeric subunits are linked together by Ala-Ala-Ala bridges. The native muramyl peptides primed human monocytes in vitro for the increased production of the microbicidal superoxide radical.

Amino Acid Sequence↗
PubMed1975

Specific recognition of choline residues in the cell wall teichoic acid by the N-acetylmuramyl-L-alanine amidase of Pneumococcus.

Pneumococci growing on choline-containing medium are known to incorporate this amino alcohol into the wall teichoic acid and produce autolysin-sensitive cell walls. In contrast, bacteria grown on the choline analogue, ethanolamine, incorporate ethanolamine into the teichoic acid and synthesize cell walls that are resistant to the homologous autolysin. In this communication, we report experiments aimed at understanding the biochemical mechanism of this phenomenon. Ethanolamine-containing (autolysin-resistant) cell walls were methylated in vitro with methyl iodide. Under appropriate conditions, virtually all of the ethanolamine residues could be converted to choline. After methylation, the formerly autolysin-resistant walls could be quantitatively hydrolyzed by the pneumococcal autolysin. Methylated walls also recovered another property typical of cell walls isolated from choline-grown bacteria: they could induce the in vitro "conversion" of an inactive form of autolysin to the catalytically active form (Tomasz, A., and Westphal, M. (1971) Proc. Natl. Acad. Sci. U.S.A. 68, 2627-2630). The results suggest that the autolysin-catalyzed hydrolysis of amide bonds in the peptidoglycan requires an additional interaction between the enzyme protein and choline residues in the teichoric acid portion of the cell wall.

Alanine↗
PubMed1989

Immunodetection of haemocyte subpopulations by N-acetylmuramic acid antibody in Planorbarius corneus (L.) (Gastropoda, Pulmonata).

The cell subpopulations in the haemolymph of Planorbarius corneus were distinguished by means of flow cytometry. An antibody against N-acetylmuramic acid was prepared and used as a cellular marker to recognize the cell types forming the subpopulations. The spreading haemocytes showed a positive reaction for anti-N-acetylmuramic acid; round haemocytes gave a negative reaction.

Animals↗
PubMed2005

A polysaccharide deacetylase homologue, PdaA, in Bacillus subtilis acts as an N-acetylmuramic acid deacetylase in vitro.

A polysaccharide deacetylase homologue, PdaA, was determined to act as an N-acetylmuramic acid deacetylase in vitro. Histidine-tagged truncated PdaA (with the putative signal sequence removed) was overexpressed in Escherichia coli cells and purified. Measurement of deacetylase activity showed that PdaA could deacetylate peptidoglycan treated with N-acetylmuramoyl-L-alanine amidase CwlH but could not deacetylate peptidoglycan treated with or without DL-endopeptidase LytF (CwlE). Reverse-phase high-performance liquid chromatography and mass spectrometry (MS) and MS-MS analyses indicated that PdaA could deacetylate the N-acetylmuramic acid residues of purified glycan strands derived from Bacillus subtilis peptidoglycan.

Amidohydrolases↗