scholarly journals Crosslinking of peptidoglycan by l , d ‐transpeptidases allows bacteria to bypass the antibacterial activity of many betalactams as well as vancomycin. NMR studies of the Enterococcus faecium l , d ‐transpeptidase have identified the binding sites for the acyl donor and the acyl acceptor of the peptidoglycan cross‐linking reaction. For details, see the article by Triboulet et al . on pp. 90–100 of this issue.

2015 ◽  
Vol 98 (1) ◽  
Keyword(s):  
Antibacterial Activity ◽  
Binding Sites ◽  
Enterococcus Faecium ◽  
Cross Linking ◽  
Acyl Donor ◽  
Nmr Studies ◽  
Acyl Acceptor

scholarly journals Persistent Interactions of Core Histone Tails with Nucleosomal DNA following Acetylation and Transcription Factor Binding

1998 ◽  
Vol 18 (11) ◽  
pp. 6293-6304 ◽  
Author(s):  
Vesco Mutskov ◽  
Delphine Gerber ◽  
Dimitri Angelov ◽  
Juan Ausio ◽  
Jerry Workman ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Molecular Biology ◽  
Binding Sites ◽  
Cross Linking ◽  
Uv Laser ◽  
Histone Tail ◽  
Histone Tails ◽  
Nucleosomal Dna ◽  
Core Histones

ABSTRACT In this study, we examined the effect of acetylation of the NH2 tails of core histones on their binding to nucleosomal DNA in the absence or presence of bound transcription factors. To do this, we used a novel UV laser-induced protein-DNA cross-linking technique, combined with immunochemical and molecular biology approaches. Nucleosomes containing one or five GAL4 binding sites were reconstituted with hypoacetylated or hyperacetylated core histones. Within these reconstituted particles, UV laser-induced histone-DNA cross-linking was found to occur only via the nonstructured histone tails and thus presented a unique tool for studying histone tail interactions with nucleosomal DNA. Importantly, these studies demonstrated that the NH2 tails were not released from nucleosomal DNA upon histone acetylation, although some weakening of their interactions was observed at elevated ionic strengths. Moreover, the binding of up to five GAL4-AH dimers to nucleosomes occupying the central 90 bp occurred without displacement of the histone NH2 tails from DNA. GAL4-AH binding perturbed the interaction of each histone tail with nucleosomal DNA to different degrees. However, in all cases, greater than 50% of the interactions between the histone tails and DNA was retained upon GAL4-AH binding, even if the tails were highly acetylated. These data illustrate an interaction of acetylated or nonacetylated histone tails with DNA that persists in the presence of simultaneously bound transcription factors.

scholarly journals The Aminolysis Reaction of Streptomyces S9 Aminopeptidase Promotes the Synthesis of Diverse Prolyl Dipeptides

2010 ◽  
Vol 76 (12) ◽  
pp. 4109-4112 ◽  
Author(s):  
Jiro Arima ◽  
Masazumi Morimoto ◽  
Hirokazu Usuki ◽  
Nobuhiro Mori ◽  
Tadashi Hatanaka
Keyword(s):  
Conversion Ratio ◽  
Acyl Donor ◽  
Acyl Acceptor ◽  
Broad Specificity

ABSTRACT Prolyl dipeptide synthesis by S9 aminopeptidase from Streptomyces thermocyaneoviolaceus (S9AP-St) has been demonstrated. In the synthesis, S9AP-St preferentially used l-Pro-OBzl as the acyl donor, yielding synthesized dipeptides having an l-Pro-Xaa structure. In addition, S9AP-St showed broad specificity toward the acyl acceptor. Furthermore, S9AP-St produced cyclo (l-Pro-l-His) with a conversion ratio of substrate to cyclo (l-Pro-l-His) higher than 40%.

scholarly journals Identification of the l,d-Transpeptidases Responsible for Attachment of the Braun Lipoprotein to Escherichia coli Peptidoglycan

2007 ◽  
Vol 189 (10) ◽  
pp. 3927-3931 ◽  
Author(s):  
Sophie Magnet ◽  
Samuel Bellais ◽  
Lionel Dubost ◽  
Martine Fourgeaud ◽  
Jean-Luc Mainardi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterococcus Faecium ◽  
Resistant Mutant ◽  
Cross Linking ◽  
Mutant Strains ◽  
Acyl Acceptors

ABSTRACT The l,d-transpeptidase Ldtfm catalyzes peptidoglycan cross-linking in β-lactam-resistant mutant strains of Enterococcus faecium. Here, we show that in Escherichia coli Ldtfm homologues are responsible for the attachment of the Braun lipoprotein to murein, indicating that evolutionarily related domains have been tailored to use muropeptides or proteins as acyl acceptors in the l,d-transpeptidation reaction.

scholarly journals Enhanced antibacterial activity through the controlled alignment of graphene oxide nanosheets

2017 ◽  
Vol 114 (46) ◽  
pp. E9793-E9801 ◽  
Author(s):  
Xinglin Lu ◽  
Xunda Feng ◽  
Jay R. Werber ◽  
Chiheng Chu ◽  
Ines Zucker ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Antibacterial Activity ◽  
Graphene Oxide ◽  
Direct Electron Transfer ◽  
Composite Films ◽  
Experimental Studies ◽  
Cross Linking ◽  
Vertical Orientation ◽  
Electron Transfer Mechanism ◽  
Vertically Aligned

The cytotoxicity of 2D graphene-based nanomaterials (GBNs) is highly important for engineered applications and environmental health. However, the isotropic orientation of GBNs, most notably graphene oxide (GO), in previous experimental studies obscured the interpretation of cytotoxic contributions of nanosheet edges. Here, we investigate the orientation-dependent interaction of GBNs with bacteria using GO composite films. To produce the films, GO nanosheets are aligned in a magnetic field, immobilized by cross-linking of the surrounding matrix, and exposed on the surface through oxidative etching. Characterization by small-angle X-ray scattering and atomic force microscopy confirms that GO nanosheets align progressively well with increasing magnetic field strength and that the alignment is effectively preserved by cross-linking. When contacted with the model bacteriumEscherichia coli, GO nanosheets with vertical orientation exhibit enhanced antibacterial activity compared with random and horizontal orientations. Further characterization is performed to explain the enhanced antibacterial activity of the film with vertically aligned GO. Using phospholipid vesicles as a model system, we observe that GO nanosheets induce physical disruption of the lipid bilayer. Additionally, we find substantial GO-induced oxidation of glutathione, a model intracellular antioxidant, paired with limited generation of reactive oxygen species, suggesting that oxidation occurs through a direct electron-transfer mechanism. These physical and chemical mechanisms both require nanosheet penetration of the cell membrane, suggesting that the enhanced antibacterial activity of the film with vertically aligned GO stems from an increased density of edges with a preferential orientation for membrane disruption. The importance of nanosheet penetration for cytotoxicity has direct implications for the design of engineering surfaces using GBNs.

Sign in / Sign up

Export Citation Format

Share Document