Inhibition of septation in Bacillus subtilis by a peptide antibiotic, edeine B(1).

A peptide antibiotic, edeine B(1), exerts a lethal action in Bacillus subtilis causing filamentous morphology. This antibiotic assumes to inhibit cell division by interacting with FtsZ and inhibiting FtsZ polymerization. The temperature-sensitive mutant ftsZ ts1 was shown to be hypersensitive to the antibiotic as compared to the parent 168 with respect to its lethal action and the sensitivity to the antibiotic of the revertant of ftsZ ts1 was shown to be intermediate between those of the parent 168 and the ftsZ ts1. Alteration of FtsZ sequence may be responsible for sensitivity to edeine B(1). The residues at 240, 278, 345 and 346 in the FtsZ sequence of the parent 168 were A240, A278, D345 and A346. Those of ftsZ ts1 were V240, V278, E345 and P346. Those of the revertant of ftsZ ts1 were A240, A278, E345 and P346. The difference in sensitivity to edeine B(1) among these strains is presumably due to the difference in the residues at 240, 278, 345 and 346 in the FtsZ sequence. The sequential events of the inhibition of FtsZ assembly and the inhibition of protein biosynthesis by edeine B(1) may progress synergistically, resulting in cell death.

The immunoregulatory effects of edeine analogues in mice.

The edeines analogs were tested in several in vitro and in vivo assays using the mouse model, with edeine B (peptide W1) and cyclosporine A as reference compounds. The peptides displayed moderate, stimulatory effects on concanavalin A-induced (ConA-induced) splenocyte proliferation, whereas their effects on pokeweed mitogen-induced (PWM-induced) splenocyte proliferation were inhibitory. The peptides inhibited lipopolysacharide-induced (LPS-induced) tumor necrosis factor alpha production but had little effect on interleukin 6 production. In the model of the humoral immune response in vitro to sheep red blood cells, peptide 1 was distinctly stimulatory in the investigated concentrations (1-100 microg/ml), whereas peptides 3 and 4 only stimulated the number of antibody-forming cells at the highest concentration (100 microg/ml). In the model of the delayed type hypersensitivity in vivo to ovalbumin, the peptides were moderately suppressive (3 being the most active). The reference peptide W1 stimulated ConA-induced cell proliferation at 1-10 microg/ml but was inhibitory at 100 microg/ml. It also inhibited PWM-induced cell proliferation in a dose-dependent manner. This peptide had no effect on the humoral immune response in vitro or on cytokine production, but inhibited DTH reaction in vivo. The relationship between structure and activity, and a possible mode of action of the peptides, is discussed in this paper.

Structure activity relationship studies on the antimicrobial activity of novel edeine A and D analogues.

Edeines are pentapeptide amide antibiotics composed of four nonprotein amino acids, glycine, and polyamine. They exhibit antimicrobial and immunosuppressive activities and are universal inhibitors of translation. Moreover, it was proven that the free ionizable carboxy group in the (2R, 6S, 7R)-2,6-diamino-7-hydroxyazelaic acid moiety is not essential for biological activity of these compounds. In this paper we describe the synthesis of four novel edeine A and D analogues in which the above-mentioned acid residue was replaced with the (3R, 4S)- or (3S, 4S)-4,5-diamino-3-hydroxypentanoic acid moiety. In one compound we also introduced into molecule the 3-N,N-dimethyl derivative of (S)-2,3-diaminopropanoic acid to prevent the transpeptidation process, which results in the loss of biological activity of alpha-isomers of edeines. All peptides were synthesized applying the active ester and azide methods and on the basis of the coupling of suitable N-terminal tripeptides with proper C-terminal dipeptide amides. The activities of the newly obtained edeine analogues against selected strains of bacteria and fungi are also presented.

Total synthesis of edeine D.

Syntheses of the peptides with sequences postulated for active and inactive isomer of edeine D were carried out. The peptides obtained were identical with natural product in regard to chromatographic and electrophoretic properties. Biological data for synthesized compounds confirmed that in active and inactive isomer isoserine is linked with the alpha- or beta-amino group of alpha, beta-diaminopropionic acid, respectively.

The antibiotic edeine. XII. Isolation and structure of edeine F.

The peptide antibiotic edeine F produced by Bacillus brevis Vm4, one of the components of edeine antibiotics complex, was isolated from a fermentation broth and was also obtained by amidination of edeine D. Edeine F is composed of amino acids: (S)-beta-phenyl-beta-alanine, (S)-isoserine, (S)-2,3-diaminopropionic acid, (2R,6S)-diamino-(7R)-hydroxyazelaic acid, glycine and a polyamine guanidylspermidine. Enzymatic degradation of antibiotic with carboxypeptidase B, dinitrophenylation of edeine and of its enzymatic degradation products and synthesis of edeine F from edeine D of known structure permitted to postulate the chemical structure for edeine F.

The selectivity of amino acid and peptide amidination with O-methylisourea.

Selectivity of amidination using ornithine as model amino acid was investigated in detail. The results obtained were taken advantage of for studying the reactions with other polyfunctional amino acids: beta-tyrosine, isoserine, 2,3-diaminopropionic acid, 2,6-diamino-7-hydroxyazelaic acid and with the pentapeptide amide, edeine A. It was found that, if the appropriate conditions are maintained, selective amidination of more basic amino groups of polyamino compounds is possible when these groups are bound to the primary alkyl.

Esters and amides of edeine A.

Methods for the synthesis of esters and amides of edeine A were developed and a number of derivatives of this type was obtained and characterized. The antimicrobial activities of the derivatives are comparable to the activity of the native antibiotic and indicate that the presence of free carboxyl group in edeine is not essential for its biological assay.