Studies on the mode of action of amiclenomycin.

Abstract

Amiclenomycin(AM) was found to be a strong inhibitor of KAPA*-DAPA* aminotransferase of Brevibacterium divaricatum.This transamination was suggested to follow Ping Pong Bi Bi mechanism.Inhibition of this transamination by AM is of a noncompetitive type in a LINEWEAVER-BURK plot of initial velocity, but not in a DIXON plot. The activity of KAPA-DAPA aminotransferase drops abruptly after preincubation with AM, but its activity is restored by dialysis against 10 mm potassium phosphate buffer (pH 7.0). Inhibition by AM is decreased by an increase of KAPA in the reaction mixture, but not by an increase of S-adenosyl-L-methionine (SAM) or pyridoxal-5'-phosphate (PALP). These facts indicate that AM exerts its inhibitory action against KAPA-DAPA aminotransferase by binding to the enzyme, probably to the KAPA-DAPA binding site.As reported in our previous paper1), amiclenomycin was thought to inhibit the KAPA- Materials and MethodsOrganisms. Brevibacterium divaricatum NRRL 2311, Pseudomonas graveolens IFO 3460 and Bacillus subtilis AKU 0236 were obtained through the courtesy of Prof. K. OGATA, Kyoto University. Preparation of enzymes. KAPA-DAPA aminotransferase was prepared from Brer. divaricatum according to the method of IZUMI et al.2) Cells grown at 27°C for 24 hours were washed, disruped in a French press (1,200 kg/cm2) and the enzyme was partially purified (ca 16 times in specific activity) by ammonium sulfate fractionation (50% saturation) and DEAE-cellulose column chromatography.The enzyme was eluted from the column with a gradient from 50 to 250 mm of potassium phosphate buffer (pH 7.0) containing 5 mm of mercaptoethanol. Active fractions were concentrated by the addition of ammonium sulfate to 60 % saturation and dialyzed against a continuous flow of 10 mm potassium phosphate buffer (pH 7.0) containing 5 mm of mercaptoethanol.The enzyme was used within 2-3 weeks after preparation. Ureido ring synthetase which converts DAPA to DTB was prepared from Ps. graleolens by the method of OGATA et al.3,4) The enzyme was partially purified (ca 16 times in specific activity) by ammonium sulfate fractionation (20-50% saturation) and DEAE-cellulose column chromatography.This enzyme preparation contained no KAPA-DAPA aminotransferase activity and was stable for at least 2 months at 4°C.Enzyme assays. The method Of OGATA (personal communication) was employed for KAPA-DAPA transamination. The basal reaction mixture (0.5 ml) contained KAPA 5 nmoles, SAM 500 nmoles, PALP 50 nmoles, potassium phosphate buffer (pH 8.0) 50 pmoles and KAPA-DAPA * KAPA:7-Keto-8-aminopelargonic acid . DAPA: 7, 8-Diaminopelargonic acid.

Inhibition of Mycobacterium tuberculosis Transaminase BioA by Aryl Hydrazines and Hydrazides

“…Amiclenomycin (ACM), a natural product extracted from Streptomyces strains, and a simplified derivative were identified many years ago as mechanism-based inhibitors of Mtb BioA. [9, 13] ACM showed good activity against Mtb cells, but failed in animal models [13] likely due to its low chemical stability. [14] More recently, mechanism-based inhibitors based on ACM with improved chemical stability have been described, but the stability comes at the expense of lower potency.…”

Structural Basis for the Inhibition of the Biosynthesis of Biotin by the Antibiotic Amiclenomycin

“…Recently, both isomers were synthesized, and it was concluded on the basis of their NMR spectra that the natural product had cis rather than trans geometry (24). Inhibition studies of DAPA synthase by ACM indicated that the inhibitor binds to the KAPA/DAPA-binding site of the enzyme (25).…”

Inhibition of 7,8-diaminopelargonic acid aminotransferase by amiclenomycin and analogues

“…In 1974, Okami and co-workers isolated a new amino acid antibiotic, amiclenomycin 1a (Scheme 1), from culture filtrates of Streptomyces lavendulae [1][2][3]. It was also isolated later, incorporated in di-or tripeptide, from Streptomyces venezulae [4,5].…”

“…It was also isolated later, incorporated in di-or tripeptide, from Streptomyces venezulae [4,5]. Okami and co-workers reported that amiclenomycin inhibited the growth of mycobacteria and that its target was DAPA AT (7,8-diaminopelargonic acid aminotransferase), a PLP (pyridoxal-5 -phosphate)-dependent enzyme involved in biotin biosynthesis [1][2][3]. However, the proposed stereochemistry for amiclenomycin proved to be wrong and the mode of action of this antibiotic was not completely understood.…”