Metabolic products of microorganisms. 228. New nikkomycins produced by mutants of Streptomyces tendae.

Abstract

Four new dipeptidyl nikkomycins of the Z-and the X-series with a variation in the amino acid moiety of the molecule were isolated from the mutant Streptomyces tendae 901/395 and characterized.Nikkomycins Kz and Kg contain 2-amino-4-hydroxy-4-(2-pyridyl)butyric acid, and nikkomycins Oz and Os 2-amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)butyric acid. In contrast to nikkomycins Z and X, nikkomycins Kx, and 0x are quite stable at alkaline pH and exhibit a lower biological activity against various test organisms. From the mutant S. tendae 901/C37, which is auxotrophic for methionine and threonine, enhanced amounts of two tripeptidyl nikkomycins, Qz and Qx, were produced which are analogues of nikkomycins J and I and contain a homoserine residue instead of glutamic acid. These nikkomycins exhibit a high pH instability.Nikkomycins are nucleoside peptide antibiotics which act as competitive inhibitors of fungal and insecticidal chitin synthetases1.2,3) From the culture filtrate of Streptomyces tendae a spectrum of active nikkomycins has been isolated4-7). The major components are the two dipeptidyl nikkomycins Z and X composed of 2-amino-4-hydroxy-4-(5-hydroxy-2-pyridyl)-3-methylbutyric acid, an unusual amino acid, and a 5-aminohexuronic acid N-glycosidically bound to uracil in nikkomycin Z or to 5-formyl-4-imidazolin-2-one in nikkomycin X. The tripeptidyl nikkomycins J and I, minor components of the culture broth, are analogues of nikkomycins Z and X with a peptidically bound glutamyl residue linked to the carboxy group of the nucleoside moiety. By mutasynthesis and directed fermentation nikkomycin Z and J analogues containing thymine, 5-hydroxymethyluracil or isoorotic acid as base could be obtained8). In the present paper we describe new nikkomycins produced by mutants of Streptomyces tendae. Materialsand Methods MicroorganismsSpores of the wild type strain Streptomyces tendae Tii 901 were mutagenized by UV light at 365 nm in the presence of 8-methoxypsoralen (MOP) according to TOWNSEND et a1.9 . 1010 spores per 10 ml saline plus 1 mg MOP were incubated for 10 minutes at 27°C and subsequently irradiated by UV light. Mutants were selected among 0.1 % survivors.Mutagenesis with ethyl methane sulfonate (EMS) was performed by incubating 109 spores of S. tendae Tii 901 per 10 ml sodium phosphate buffer, pH 7.0 with 5 % (v/v) EMS at 27°C. Mutants were t

Molecular characterization of co-transcribed genes from Streptomyces tendae Tü901 involved in the biosynthesis of the peptidyl moiety and assembly of the peptidyl nucleoside antibiotic nikkomycin

“…nikV insertion mutants were not able to form nikkomycins containing HPHT as the peptidyl moiety, but instead accumulated nikkomycins O z and O x , which contain a peptidyl moiety consisting of HPHT without the methyl group at carbon-3. These nikkomycins had previously been isolated from culture ®ltrates of the S. tendae mutant TuÈ 901/395 obtained after UV treatment (Bormann et al 1985). The phenotype of nikV mutants can be rationalized by assuming that a primary metabolite, presumably pyruvate, is used as an alternate substrate by NikB, yielding the peptidyl moiety of nikkomycins O x and O z .…”

“…The strains were grown for 6 days in production medium. Peaks corresponding to nikkomycins C z , C x , O z , O x , Z, X, J, and I are indicated times and characteristic ultraviolet spectra, which were identical to those of reference substances (Bormann et al 1985). In addition to nikkomycins O z and O x (150 mg/l), nikV mutants accumulated the nucleoside moieties nikkomycins C z and C x (350 mg/l).…”

Nutritional control of nikkomycin and juglomycin production by Streptomyces tendae in continuous culture

“…New nikkomycins have been found and isolated by using a photodiode array detector (Fiedler 1984) or mutation techniques (Delzer et al 1984;Bormann et al 1985). For many years it has been known that the strain Streptornyces tendae is able to produce juglomycins as well, Offprint requests to: D. Hege-Treskatis another group of antibiotics very different from nikkomycins (Langh~irig 1978;Werner 1982).…”

Compounds active against cell walls of medically important fungi

“…In the case of the polyoxins, several derivatives with different amino acid or amino fatty acid compositions were prepared with the hope of improving uptake and biological activity (81,138,144,221,222). With the nikkomycins, the group led by H. Zahner used a different approach in that they first mutagenized the producing strain of Streptomyces tendae and then ran a directed fermentation providing pyrimidines, purines, imidazoles, or amino acids (24,25,66,67,69,101,114 Complicating the issue of differing susceptibilities is a recent report that suggests that, with S. cerevisiae, the gene products of CHSI and CHS2 show differential susceptibilities to the inhibitory effects of polyoxins and nikkomycins, with Chsl being more susceptible (34). As it has been confirmed that several different medically important fungi also have multiple forms of chitin synthetase (26), it is an obvious statement that a determination of the relative importance of each form to the growth of the cell must be made.…”