Genes Involved in Formation and Attachment of a Two-Carbon Chain as a Component of Eurekanate, a Branched-Chain Sugar Moiety of Avilamycin A

Abstract

Eurekanate belongs to the important class of branched-chain carbohydrates present in a wide variety of natural sources. It is a component of avilamycin A, a potent inhibitor of bacterial protein synthesis targeting the 50S ribosomal subunit. The present work provides experimental proof for the function of two genes of the avilamycin biosynthetic gene cluster, aviB1 and aviO2, that are both involved in avilamycin structure modification. The functions of both genes were identified by gene inactivation experiments and nuclear magnetic resonance analyses of extracts produced by the mutants. We suggest that both AviO2 and AviB1 are involved in the biosynthesis of eurekanate within avilamycin biosynthesis. Moreover, two other genes (aviO1 and aviO3) have been inactivated, resulting in a breakdown of avilamycin production in the mutants ITO1 and ITO3, which clearly shows the essential role of both enzymes in avilamycin biosynthesis. The exact functions of both aviO1 and aviO3 remained unknown.

The Active Conformation of Avilamycin A Is Conferred by AviX12, a Radical AdoMet Enzyme

“…Compared with gavibamycin N1 and avilamycin A, this compound is lacking the acetyl moiety in ring H, which is replaced by a hydrogen. This result is analogous to the changes reported for the mutations ITB1 and ITO2 (10).…”

“…Gene disruption experiments with putative methyltransferase genes have led to new avilamycin derivatives with enhanced water solubility, named gavibamycins (2). After deletion of aviB1 and aviO2, components of an incomplete pyruvate-dehydrogenase complex, an avilamycin derivative was obtained lacking the terminal acetyl residue at position C-4 of the eurekanate moiety of avilamycin A (10).…”

Biosynthesis of amycolamicin: the biosynthetic origin of a branched α-aminoethyl moiety in the unusual sugar amycolose

“…The twocarbon branch may be biosynthesized from pyruvate, which has been studied using isotope tracer experiments, 13-15 enzyme reactions 16 and gene inactivations. 17 However, these modifications for the two-carbon branched chain are restricted to the aoxoethyl or a-hydroxyethyl branch, and nothing has been reported for the a-aminoethyl branch. In this paper, we report the origin of a branched a-aminoethyl moiety, which we investigated with a feeding experiment that uses the stable-isotope-labeled pyruvate.…”

Oxidative cyclizations in orthosomycin biosynthesis expand the known chemistry of an oxygenase superfamily

“…Deletion of aviO2 (evdO2 homolog) from S. viridochromogenes Tü57 resulted in a new peak in the mass spectrum, interpreted as the loss of the acetyl group on C4 of the H-ring (see Fig. 1A for location) (40). Given that an AKG/Fe(II)-dependent oxygenase is unlikely to catalyze acetylation and that the homologous oxygenase is present in the evd and eve gene clusters despite the absence of an acetyl group on everninomicin congeners, an alternative interpretation of this result is that AviO2 catalyzes a ring closure before acetylation and that this ring closure is required for substrate recognition by an acetylating enzyme.…”