scholarly journals Elucidating Peptidoglycan Structure: An Analytical Toolset

2019 ◽  
Vol 27 (7) ◽  
pp. 653-654 ◽  
Author(s):  
Sara Porfírio ◽  
Russell W. Carlson ◽  
Parastoo Azadi
Keyword(s):  
Peptidoglycan Structure

scholarly journals Microlunatus soli sp. nov., isolated from soil

2010 ◽  
Vol 60 (4) ◽  
pp. 824-827 ◽  
Author(s):  
P. Kämpfer ◽  
Chiu-Chung Young ◽  
H.-J. Busse ◽  
Jiunn-Nan Chu ◽  
P. Schumann ◽  
...  
Keyword(s):  
Edible Mushroom ◽  
Diaminopimelic Acid ◽  
Rrna Gene ◽  
Biochemical Tests ◽  
Glycine Residue ◽  
Gene Sequence Analysis ◽  
Peptidoglycan Structure ◽  
Unknown Phospholipid ◽  
Type Strains ◽  
Physiological And Biochemical

A Gram-stain-positive, coccoid, non-endospore-forming actinobacterium (strain CC-12602T) was isolated from a spawn used for growing the edible mushroom Agaricus brasiliensis in the laboratory. On the basis of 16S rRNA gene sequence analysis, strain CC-12602T was shown to belong to the genus Microlunatus and was related most closely to the type strains of Microlunatus ginsengisoli (96.1 % similarity), M. phosphovorus (95.9 %), M. panaciterrae (95.8 %) and M. aurantiacus (95.5 %). The quinone system comprised menaquinone MK-9(H4) as the major component and the polyamine pattern consisted of spermidine and spermine as major compounds. The predominant polar lipids were phosphatidylglycerol and unknown phospholipid PL3. Moderate amounts of diphosphatidylglycerol, an unknown glycolipid and three unknown phospholipids and minor amounts of an unknown phospholipid and a polar lipid were detected. The peptidoglycan type was A3γ′, based on ll-2,6-diaminopimelic acid with an interpeptide bridge consisting of a single glycine residue and a second glycine residue at position 1 of the peptide subunit. Peptidoglycan structure and major fatty acids (anteiso-C15 : 0, iso-C16 : 0 and iso-C15 : 0) supported the affiliation of strain CC-12602T to the genus Microlunatus. The results of physiological and biochemical tests allowed strain CC-12602T to be differentiated phenotypically from recognized Microlunatus species. Strain CC-12602T is therefore considered to represent a novel species of the genus Microlunatus, for which the name Microlunatus soli sp. nov. is proposed. The type strain is CC-12602T (=DSM 21800T =CCM 7685T).

scholarly journals Peptidoglycan Cross-Linking in Glycopeptide-Resistant Actinomycetales

2014 ◽  
Vol 58 (3) ◽  
pp. 1749-1756 ◽  
Author(s):  
Jean-Emmanuel Hugonnet ◽  
Nabila Haddache ◽  
Carole Veckerlé ◽  
Lionel Dubost ◽  
Arul Marie ◽  
...  
Keyword(s):  
Streptomyces Coelicolor ◽  
Residual Activity ◽  
Resistance Mechanisms ◽  
Strain Atcc ◽  
Glycopeptide Resistance ◽  
Content Type ◽  
Peptidoglycan Structure ◽  
Cross Links ◽  
Acyl Donors ◽  
Hydrolysis Of

ABSTRACTSynthesis of peptidoglycan precursors ending ind-lactate (d-Lac) is thought to be responsible for glycopeptide resistance in members of the orderActinomycetalesthat produce these drugs and in related soil bacteria. More recently, the peptidoglycan of several members of the orderActinomycetaleswas shown to be cross-linked byl,d-transpeptidases that use tetrapeptide acyl donors devoid of the target of glycopeptides. To evaluate the contribution of these resistance mechanisms, we have determined the peptidoglycan structure ofStreptomyces coelicolorA(3)2, which harbors avanHAXgene cluster for the production of precursors ending ind-Lac, andNonomuraeasp. strain ATCC 39727, which is devoid ofvanHAXand produces the glycopeptide A40296. Vancomycin retained residual activity againstS. coelicolorA(3)2 despite efficient incorporation ofd-Lac into cytoplasmic precursors. This was due to ad,d-transpeptidase-catalyzed reaction that generated a stem pentapeptide recognized by glycopeptides by the exchange ofd-Lac ford-Ala and Gly. The contribution ofl,d-transpeptidases to resistance was limited by the supply of tetrapeptide acyl donors, which are essential for the formation of peptidoglycan cross-links by these enzymes. In the absence of a cytoplasmic metallo-d,d-carboxypeptidase, the tetrapeptide substrate was generated by hydrolysis of the C-terminald-Lac residue of the stem pentadepsipeptide in the periplasm in competition with the exchange reaction catalyzed byd,d-transpeptidases. InNonomuraeasp. strain ATCC 39727, the contribution ofl,d-transpeptidases to glycopeptide resistance was limited by the incomplete conversion of pentapeptides into tetrapeptides despite the production of a cytoplasmic metallo-d,d-carboxypeptidase. Since the level of drug production exceeds the level of resistance, we propose thatl,d-transpeptidases merely act as a tolerance mechanism in this bacterium.

Structure and uptake mechanism of bacteriocins targeting peptidoglycan renewal

2012 ◽  
Vol 40 (6) ◽  
pp. 1560-1565 ◽  
Author(s):  
Kornelius Zeth
Keyword(s):  
Outer Membrane ◽  
Periplasmic Space ◽  
Uptake Mechanism ◽  
Inner Membrane ◽  
Cytoplasmic Dna ◽  
Peptidoglycan Structure ◽  
Colicin M ◽  
Translocation Domain ◽  
Energy Dependent ◽  
Activity Domain

Bacteriocins are narrow-spectrum protein antibiotics released to kill related bacteria of the same niche. Uptake of bacteriocins depends critically on the presence of an uptake receptor in the outer membrane, a translocation pore and an energy-dependent activating system of the inner membrane. Most bacteriocins act on the inner membrane as pore-forming toxins or they target cytoplasmic DNA/RNA and ribosomal synthesis respectively. Only two bacteriocins are known to become activated in the periplasmic space and to inhibit the renewal process of the peptidoglycan structure. In Escherichia coli, the Cma (colicin M) phosphatase is activated in the periplasmic space by the FkpA chaperone and subsequently degrades the C55-PP precursor unit of the peptidoglycan. Pst (pesticin) from Yersinia pestis carries a lysozyme homology domain to degrade peptidoglycan. Import of Pst is only achieved if the N-terminal translocation domain can span the outer membrane and if extensive unfolding of the protein during membrane passage is permitted. There is considerable plasticity in the import pathway since a chimaera comprising the activity domain replaced by T4 lysozyme is also translocated and active in killing those bacteria carrying the FyuA receptor.

scholarly journals A Single Dual-Function Enzyme Controls the Production of Inflammatory NOD Agonist Peptidoglycan Fragments by Neisseria gonorrhoeae

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Jonathan D. Lenz ◽  
Kathleen T. Hackett ◽  
Joseph P. Dillard
Keyword(s):  
Immune Responses ◽  
Neisseria Gonorrhoeae ◽  
Resistant Organism ◽  
Endopeptidase Activity ◽  
Peptidoglycan Structure ◽  
Cross Links ◽  
Osmotic Lysis ◽  
Bacterial Cell Shape ◽  
Immune Detection ◽  
Single Enzyme

ABSTRACT Neisseria gonorrhoeae gonococcus (GC) is a Gram-negative betaproteobacterium and causative agent of the sexually transmitted infection gonorrhea. During growth, GC releases lipooligosaccharide (LOS) and peptidoglycan (PG) fragments, which contribute significantly to the inflammatory damage observed during human infection. In ascending infection of human Fallopian tubes, inflammation leads to increased risk of ectopic pregnancy, pelvic inflammatory disease, and sterility. Of the PG fragments released by GC, most are disaccharide peptide monomers, and of those, 80% have tripeptide stems despite the observation that tetrapeptide stems make up 80% of the assembled cell wall. We identified a serine-protease l,d-carboxypeptidase, NGO1274 (LdcA), as the enzyme responsible for converting cell wall tetrapeptide-stem PG to released tripeptide-stem PG. Unlike characterized cytoplasmic LdcA homologs in gammaproteobacteria, LdcA in GC is exported to the periplasm, and its localization is critical for its activity in modifying PG fragments for release. Distinct among other characterized l,d-carboxypeptidases, LdcA from GC is also capable of catalyzing the cleavage of specific peptide cross-bridges (endopeptidase activity). To define the role of ldcA in pathogenesis, we demonstrate that ldcA disruption results in both loss of NOD1-dependent NF-κB activation and decreased NOD2-dependent NF-κB activation while not affecting Toll-like receptor (TLR) agonist release. Since the human intracellular peptidoglycan receptor NOD1 (hNOD1) specifically recognizes PG fragments with a terminal meso-DAP rather than d-alanine, we conclude that LdcA is required for GC to provoke NOD1-dependent responses in cells of the human host. IMPORTANCE The macromolecular meshwork of peptidoglycan serves essential functions in determining bacterial cell shape, protecting against osmotic lysis, and defending cells from external assaults. The conserved peptidoglycan structure, however, is also recognized by eukaryotic pattern recognition receptors, which can trigger immune responses against bacteria. Many bacteria can induce an inflammatory response through the intracellular peptidoglycan receptor NOD1, but Neisseria gonorrhoeae serves as an extreme example, releasing fragments of peptidoglycan into the environment during growth that specifically antagonize human NOD1. Understanding the peptidoglycan breakdown mechanisms that allow Neisseria to promote NOD1 activation, rather than avoiding or suppressing immune detection, is critical to understanding the pathogenesis of this increasingly drug-resistant organism. We identify a peptidoglycan l,d-carboxypeptidase responsible for converting liberated peptidoglycan fragments into the human NOD1 agonist and find that the same enzyme has endopeptidase activity on certain peptidoglycan cross-links, the first described combination of those two activities in a single enzyme. IMPORTANCE The macromolecular meshwork of peptidoglycan serves essential functions in determining bacterial cell shape, protecting against osmotic lysis, and defending cells from external assaults. The conserved peptidoglycan structure, however, is also recognized by eukaryotic pattern recognition receptors, which can trigger immune responses against bacteria. Many bacteria can induce an inflammatory response through the intracellular peptidoglycan receptor NOD1, but Neisseria gonorrhoeae serves as an extreme example, releasing fragments of peptidoglycan into the environment during growth that specifically antagonize human NOD1. Understanding the peptidoglycan breakdown mechanisms that allow Neisseria to promote NOD1 activation, rather than avoiding or suppressing immune detection, is critical to understanding the pathogenesis of this increasingly drug-resistant organism. We identify a peptidoglycan l,d-carboxypeptidase responsible for converting liberated peptidoglycan fragments into the human NOD1 agonist and find that the same enzyme has endopeptidase activity on certain peptidoglycan cross-links, the first described combination of those two activities in a single enzyme.

scholarly journals Helicobacter pylori Csd4 is a peptidoglycan metallocarboxypeptidase

2014 ◽  
Vol 70 (a1) ◽  
pp. C442-C442
Author(s):  
Anson Chan ◽  
Yanjie Liu ◽  
Kris Blair ◽  
Emilisa Frirdich ◽  
Erin Gaynor ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Cell Shape ◽  
Diaminopimelic Acid ◽  
Specific Substrate ◽  
Substrate Molecule ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Peptidoglycan Structure ◽  
Unit Cell Dimensions

The bacterial cell wall is a polymeric structure that determines the overall shape of the cell and undergoes constant remodelling during cell growth, requiring enzymes that cleave the existing peptidoglycan structure. Csd4 is an enzyme important for cell shape as deleting it in Helicobacter pylori causes the helical-shaped cells to become rod-like. Csd4 is a zinc carboxypeptidase that can cleave the tripeptide moiety found in peptidoglycan (i.e. L-Ala-γ-D-Glu-m-DAP) to release meso-diaminopimelic acid (mDAP). Structures of Csd4 were solved by X-ray crystallography up to 1.75 Å resolution in space group P212121 with zinc and substrate/product bound and contain the same unit cell dimensions. Csd4 is a monomeric enzyme with three domains: an N-terminal M14-family carboxypeptidase domain followed by two smaller domains likely important in protein-protein or protein-peptidoglycan interactions. Key interactions are observed between the protein and substrate in the active site, supporting specific substrate recognition by Csd4. A water or hydroxide molecule, which is required for catalytic activity, is also observed bound to the zinc and is poised to interact with the substrate molecule upon activation.

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