Identification of the Formycin A Biosynthetic Gene Cluster from Streptomyces kaniharaensis Illustrates the Interplay between Biological Pyrazolopyrimidine Formation and de Novo Purine Biosynthesis

Abstract

Formycin A is a potent purine nucleoside antibiotic with a C-glycosidic linkage between the ribosyl moiety and the pyrazolopyrimidine base. Herein, a cosmid is identified from the Streptomyces kaniharaensis genome library that contains the for gene cluster responsible for the biosynthesis of formycin. Subsequent gene deletion experiments and in vitro characterization of the forBCH gene products established their catalytic functions in formycin biosynthesis. Results also demonstrated that PurH from de novo purine biosynthesis plays a key role in pyrazolopyrimidine formation during biosynthesis of formycin A. The participation of PurH in both pathways represents a good example of how primary and secondary metabolism are interlinked.

Comparative investigation into formycin A and pyrazofurin A biosynthesis reveals branch pathways for the construction ofC-nucleoside scaffolds

“…2A, Tables 1, S1). As anticipated, in silico analysis indicated that the genes for FOR-A and COF biosynthesis are linked together as reported by a recent study (19). Moreover, there are 7 additional genes ( forW, forV, forO, forG, cof25, cof26 , and cof29 ) in S. kaniharaensis ATCC 21070 (Table S1), and it is proposed to execute some alternative functions during FOR-A and COF biosynthesis in this strain.…”

“…6A), and related biochemical studies in our laboratory are now ongoing. Once the C -glycosidic bond constructed, the later tailoring enzymatic steps are highly similar to those in the de novo purine pathway, which has already been illustrated in two recent studies (19, 26).…”

“…Moreover, Ochi et al , confirmed that N-3, N-7, and N-8 of FOR-A originate from the ε-amino nitrogen of lysine (18). More recently, Wang et al , identified the FOR-A biosynthetic gene cluster on the basis of previous studies (19), and deciphered the tailoring steps to FOR-A biosynthesis, by which they have established that FOR-A biosynthesis shares a crosstalk with the de novo purine pathway (19). Although a pathway for FOR-A biosynthesis was tentatively proposed, several important aspects have still remained unveiled.…”

The biosynthetic gene cluster of the C-nucleoside antibiotic pyrazomycin with a rare pyrazole moiety

“…This gene cluster contains af our-gene subcluster (pyrOPQS)t hat has been linked to the biosynthesis of coformycin,t he production of which seems to be associated with many nucleoside family natural products (Figure S1 A). [18,19] Moreover, the pyr cluster also contains pyrE,w hich shows sequence homology to genes that encode( b-ribofuranosylamino)benzene 5'-phosphate (b-RFAP) synthase. In the biosynthesis of methanopterin, b-RFAP synthase catalyzes the condensation of p-aminobenzoic acid with phosphoribosylpyrophosphate throughaC -glycosidic linkage.…”

“…[7] We note that the pyr clusters hares many homologous genes with the recently reported formycinb iosynthetic gene cluster (for cluster). [19] In view of the great structural similarity between pyrazomycina nd formycin, it is not unexpected that they might use similarb iosynthetic genes. Ta ken together,o ur in silico analysis suggested that the pyr cluster might be responsible for PZN assembly in S. candidus NRRL 3601.…”