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CmlI is an N-oxygenase in the biosynthesis of chloramphenicol.

ABSTRACT: The N-oxygenation of an amine group is one of the steps in the biosynthesis of the antibiotic chloramphenicol. The non-heme di-iron enzyme CmlI was identified as the enzyme catalyzing this reaction through bioinformatics studies and reconstitution of enzymatic activity. In vitro reconstitution was achieved using phenazine methosulfate and NADH as electron mediators, while in vivo activity was demonstrated in Escherichia coli using two substrates. Kinetic analysis showed a biphasic behavior of the enzyme. Oxidized hydroxylamine and nitroso compounds in the reaction were detected both in vitro and in vivo based on LC-MS. The active site metal was confirmed to be iron based on a ferrozine assay. These findings provide new insights into the biosynthesis of chloramphenicol and could lead to further development of CmlI as a useful biocatalyst.

SUBMITTER: Lu H

PROVIDER: S-EPMC3863359 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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CmlI is an <i>N</i>-oxygenase in the biosynthesis of chloramphenicol.

Lu Haige H Chanco Emmanuel E Zhao Huimin H

Tetrahedron 20120901 37

The N-oxygenation of an amine group is one of the steps in the biosynthesis of the antibiotic chloramphenicol. The non-heme di-iron enzyme CmlI was identified as the enzyme catalyzing this reaction through bioinformatics studies and reconstitution of enzymatic activity. In vitro reconstitution was achieved using phenazine methosulfate and NADH as electron mediators, while in vivo activity was demonstrated in <i>Escherichia coli</i> using two substrates. Kinetic analysis showed a biphasic behavio ...[more]

PMID: 24347692

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Project description:In members of genus Streptomyces, AdpA is a master transcriptional regulator that controls the expression of hundreds of genes involved in morphological differentiation, secondary metabolite biosynthesis, chromosome replication, etc. However, the function of AdpASv, an AdpA ortholog of Streptomyces venezuelae, is unknown. This bacterial species is a natural producer of chloramphenicol and has recently become a model organism for studies on Streptomyces. Here, we demonstrate that AdpASv is essential for differentiation and antibiotic biosynthesis in S. venezuelae and provide evidence suggesting that AdpASv positively regulates its own gene expression. We speculate that the different modes of AdpA-dependent transcriptional autoregulation observed in S. venezuelae and other Streptomyces species reflect the arrangement of AdpA binding sites in relation to the transcription start site. Lastly, we present preliminary data suggesting that AdpA may undergo a proteolytic processing and we speculate that this may potentially constitute a novel regulatory mechanism controlling cellular abundance of AdpA in Streptomyces. IMPORTANCEStreptomyces are well-known producers of valuable secondary metabolites which include a large variety of antibiotics and important model organisms for developmental studies in multicellular bacteria. The conserved transcriptional regulator AdpA of Streptomyces exerts a pleiotropic effect on cellular processes, including the morphological differentiation and biosynthesis of secondary metabolites. Despite extensive studies, the function of AdpA in these processes remains elusive. This work provides insights into the role of a yet unstudied AdpA ortholog of Streptomyces venezuelae, now considered a novel model organism. We found that AdpA plays essential role in morphological differentiation and biosynthesis of chloramphenicol, a broad-spectrum antibiotic. We also propose that AdpA may undergo a proteolytic processing that presumably constitutes a novel mechanism regulating cellular abundance of this master regulator.

Dataset Information

CmlI is an N-oxygenase in the biosynthesis of chloramphenicol.

Publications

CmlI is an <i>N</i>-oxygenase in the biosynthesis of chloramphenicol.

Similar Datasets

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