Biosynthesis of virginiae butanolide A, a butyrolactone autoregulator from Streptomyces

Abstract

Virginiae butanolide A (VB A) (3) is one of the virginiamycin-inducing factors from Streptomyces virginiae and has a unique 2,3-disubstituted butanolide skeleton which is common to other signal molecules in Streptomyces. The biosynthesis of 3 in Streptomyces antibioticus, a high producer of 3, was studied by experiments with labeled precursors. I3C and *H NMR results as well as CI-MS analyses of dibenzoate samples indicated that the probable biosynthetic pathway to 3 involved coupling between a 8-keto acid derivative and a C3 unit from glycerol, such as dihydroxyacetone or a derivative.Signal molecules which regulate secondary metabolite production or cytodifferentiation of Streptomyces have been known for nearly 20 years. The first one was A factor (1) found by Khokhlov et al., which induces formation of streptomycin, aerial mycelium, and spores in Streptomyces griseus.' After the discovery of A factor, Grlfe et al. isolated factor 1 (2) from the Recently we found a strain of Streptomyces antibioticus which produces several milligrams of VB A per liter of culture broth,9 and this finding has made it possible to elucidate the biosynthesis of 3 by feeding experiments with Wlabeled precursors. We have detected. (8) (a) Kim, H. S.; Tada, H.; Nihira, T.; Yamada, Y. J. Anribiot. 1990, 43,692-706. (b) Kim, H. S.; Nihira, T.; Tada, H.; Yamada, Y. Ibid. 1989, 42, 769-778. (c) Miyake, K.; Horinouchi, S.; Yoshida, M.; Chiba, N.; Mori, K.; Nogawa, N.; Morikawa, N.; Beppu, T.Abstract: Pyrrolosine, a C-nucleoside recently isolated from Streptomyces albus, was assigned structure 1 by Ikegami and ceworkers largely on the basis of single-crystal X-ray diffraction. This is also the structure previously assigned to the synthetic C-nucleoside, 9-deazainosine. Because the physical and biological properties of the two compounds differ, Ikegami and co-workers suggested that the structure of 9-deazainosine should be reinvestigated. However, it is shown in this paper that the structure they proposed for pyrrolosine is incorrect. Furthermore, on the basis of the reported physical properties, it is shown that pyrrolosine is actually the known furo[3,2-d]pyrimidine C-nucleoside adenosine analogue 2. This conclusion, which is more consistent

barS1, a Gene for Biosynthesis of a γ-Butyrolactone Autoregulator, a Microbial Signaling Molecule Eliciting Antibiotic Production inStreptomycesSpecies

“…Regarding the biosynthetic pathway of the autoregulators, we have previously established a plausible pathway mainly by feeding precursors labeled with radioactive or stable isotopes (27,28) (Fig. 1B).…”

“…VB-A produced by rBarS1 was purified as dibenzoate by C 18 reverse-phase HPLC (32), and the chemical structure was verified by 600 MHz 1 H-nuclear magnetic resonance and CI-MS with the data reported previously (27). The product was then analyzed by chiral HPLC to determine the optical purity.…”

“…Dibenzoyl derivatives of VB-C 4 , VB-C 5 , VB-C 6 , VB-A, VB-D (VB-C 7 ), VB-type isomer of SCB1, VB-C 8 , and VB-C 9 were eluted at 9.78, 12.5, 16.5, 21.0, 23.0, 27.2, 30.4, and 44.1 min, respectively. (Ϯ)-6-Dehydro-VB-A, racemic A-factor C 4 ϳC 9 , racemic A-factor, racemic VB-A, racemic VB-C 4 ϳC 9 , and racemic VB-type isomer of SCB1 were chemically synthesized as described elsewhere (23,27,36). Racemic standards of VB dibenzoates were prepared similarly by benzoylation of corresponding racemic VBs, and their identities were confirmed by chemical ionization-mass spectrometry (CI-MS).…”

Biosynthesis of γ-butyrolactone autoregulators that switch on secondary metabolism and morphological development in Streptomyces

“…However, the AfsA function has been controversial (12,13). Concerning the biosynthesis pathway, Sakuda et al (1,14,15) proposed a route on the basis of feeding experiments in VB-producing Streptomyces antibioticus (see pathway A in Fig. 1).…”

Estudos sobre a síntese de butirolactonas auto-reguladoras de bactérias Streptomyces.

“…29 Entretanto, tem sido muito difícil estudar a biossíntese desses compostos, pois esses autoreguladores geralmente são produzidos apenas em quantidades de traços nas culturas de células; por exemplo, somente alguns microgramas da "virginiae" butanolida A (1) foram obtidos a partir de 1 litro de cultura de Streptomyces virginiae. 30 Por causa disso, a obtenção de amostras sintéticas dessas moléculas são muito importantes para a investigação de suas funções biológicas.…”