The surface charge as well as the electrochemical properties and ligand binding abilities of the Gram-positive cell wall is controlled by the D-alanylation of the lipoteichoic acid. The incorporation of D-Ala into lipoteichoic acid requires the D-alanine:D-alanyl carrier protein ligase (DltA) and the carrier protein (DltC). We have heterologously expressed, purified, and assayed the substrate selectivity of the recombinant proteins DltA with its substrate DltC. We found that apo-DltC is recognized by both endogenous 4'-phosphopantetheinyl transferases AcpS and Sfp. After the biochemical characterization of DltA and DltC, we designed an inhibitor (D-alanylacyl-sulfamoyl-adenosine), which is able to block the D-Ala adenylation by DltA at a K(i) value of 232 nM vitro. We also performed in vivo studies and determined a significant inhibition of growth for different Bacillus subtilis strains when the inhibitor is used in combination with vancomycin.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1742-4658.2005.04700.x

Inhibition of the D-alanine:D-alanyl carrier protein ligase from Bacillus subtilis increases the bacterium's susceptibility to antibiotics that target the cell wall.

Trapping interactions between catalytic domains and carrier proteins of modular biosynthetic enzymes with chemical probes

Novel aminoacyl sulfamides are described. These compounds are effective in the treatment of hyperproliferative disorders, specifically psoriasis. Exemplary compounds of this invention are 5'-deoxy-adenosine 5'-N(N-L-phenylalanyl)sulfamide and 5'-deoxy-adenosine 5'-N-(N-L-tryptophanyl)sulfamide.

Aminoacyl sulfamides for the treatment of hyperproliferative disorders

Nucleocidin, a fairly broad antibacterial and trypanocidal agent produced by Streptomyces calvus, has the unique structure of 4′-α-fluoro-5′-O-sulfamoyl adenosine. This nucleoside antibiotic has been a target for organic synthesis in past decades; however, microbial large-scale production has not been established due to low yield and poor reproducibility. To activate the dormant secondary metabolism of S. calvus, we examined the effect of an rpoB mutation that was induced by ultraviolet light irradiation. The resulting rifampicin-resistant strains showed remarkably improved antibiotic activity, which was extracted by n-butanol and identified by Electron-Spray-Ionization Mass Spectrometry. DNA sequencing identified double mutations, C1309A and C1318A, in the rpoB gene (according to the numbering of Streptomyces coelicolor rpoB). The resulting amino acid substitutions, H437N and R440S, corresponded to two of the previously reported amino acid substitutions that allowed the activation of dormant actinorhodin production in S. lividans 66.

https://www.jstage.jst.go.jp/article/saj/23/2/23_SAJ230205/_pdf

Enhanced Production of the Fluorinated Nucleoside Antibiotic Nucleocidin by a rifR-Resistant Mutant of Streptomyces calvus IFO13200

A newly isolated strain of Streptomyces sp. produces a new nucleoside antibiotic, ascamycin and the corresponding dealanyl derivative. The structure of ascamycin was determined to be 2-chloro-9-beta-[5-O-(N-L-alanyl)sulfamoyl-D-ribofuranosyl]-adenine. Remarkable selective toxicity of ascamycin compared to the dealanyl derivative was accounted for on the basis of a dealanylating enzyme present in the envelope of sensitive bacteria. After dealanylation, it becomes permeable to cell membrane.

H Kusakabe

Papers

Structure and biological activity of ascamycin, a new nucleoside antibiotic