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Pristinamycin I biosynthesis in Streptomyces pristinaespiralis: molecular characterization of the first two structural peptide synthetase genes

De Crécy-Lagard V., Blanc V., Gil P., Naudin L., Lorenzon S., Famechon A., Bamas-Jacques N., Crouzet J., Thibaut D.. 1997. Journal of Bacteriology, 179 (3) : p. 705-713.

Two genes involved in the biosynthesis of the depsipeptide antibiotics pristinamycins I (PI) produced by Streptomyces pristinaespiralis were cloned and sequenced. The 1.7-kb snbA gene encodes a 3-hydroxypicolinic acid: AMP ligase, and the 7.7-kb snbC gene encodes PI synthetase 2, responsible for incorporating L-threonine and L-aminobutyric acid in the PI macrocycle. snbA and snbC, which encode the two first structural enzymes of PI synthesis, are not contiguous. Both genes are located in PI-specific transcriptional units, as disruption of one gene or the other led to PI-deficient strains producing normal levels of the polyunsaturated macrolactone antibiotic pristinamycin II, also produced by S. pristinaespiralis. Analysis of the deduced amino acid sequences showed that the SnbA protein is a member of the adenylate-forming enzyme superfamily and that the SnbC protein contains two amino acid-incorporating modules and a C-terminal epimerization domain. A model for the initiation of PI synthesis analogous to the established model of initiation of fatty acid synthesis is proposed. (Résumé d'auteur)

Mots-clés : biosynthèse; clonage moléculaire; gène; antibiotique

Thématique : Physiologie et biochimie animales

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