Comparison of actinomycin peptide synthetase formation in Streptomyces chrysomallus and Streptomyces antibioticus

Abstract

Actinomycin peptide synthetase genes constitute two oppositely oriented transcriptional units, acmADR, and acmBC, separated by a non-coding intergenic region. Gene constructs of the intergenic region together with its adjoining gene acmA or acmB from the actinomycin biosynthetic gene cluster of Streptomyces chrysomallus were transferred into Streptomyces lividans TK64. Each construct expressed the respective synthetase indicating divergent promoters. Primer extension revealed for both directions −10 and −35 boxes similar to σ 70 -dependent promoters from Streptomyces and E. coli. No conspicuous regulatory sequences were detected. Accordingly, S. chrysomallus-grown in glucose-containing medium-produced the peptide synthetases AcmA and AcmB/C as well as actinomycin during logarithmic growth phase. Alignments with the corresponding intergenic region of the actinomycin biosynthetic gene cluster in Streptomyces antibioticus identified analogous −10 and −35 boxes of σ 70 consensus sequence. However, in S. antibioticus-cultivated in the same conditions-AcmA and AcmB/C were at maximum activity in late log phase and actinomycin formation peaked in stationary phase. The different patterns of formation of actinomycin and its peptide synthetases encoded by the highly homologous actinomycin biosynthetic gene clusters in S. chrysomallus and S. antibioticus suggest strain-specific control of biosynthesis in agreement with absence of pathway-specific regulatory genes. K E Y W O R D Sactinomycin, peptide synthetases, promoter, regulation, Streptomyces

Methyltransferases: Green Catalysts for Friedel–Crafts Alkylations

“…Although Fawaz and Jones, Gerratana et al., and Bachmann et al. suggest 5 as the substrate for the methyltransferase from Streptomyces antibioticus (IMRU 3720, DSMZ 41481), SibL from Streptosporangium sibiricum and Orf19 from Streptomyces refuineus , respectively, Keller and co‐workers describe 3‐hydroxykynurenine (3‐HK; 4 ) as the methyltransferase substrate in Streptomyces chrysomallus ,. Support for 4 comes from a recent structure elucidation of the ternary complex SibL/SAH/3‐HK .…”