Objective: To explore the role of sgvS in the biosynthesis of 3-hydroxypicolinic acid moiety of viridogrsein, and to analyze the substrate specificity of 3-hydroxypicolinic acid moiety in the viridogrsein biosynthetic pathway.
Methods: Through gene insertion inactivation and in trans complementation strategies, we obtained the gene inactivation mutant sgvS andits complementation mutant deltasgvS :: sgvS. Meanwhile, we fed 3-hydroxypicolinic acid, picolinic acid, 2-piperidinecarboxylic acid, 3-chloropyridinecarboxylic acid, 4-chloropyridinecarboxylic acid, 3,5-chloropyridinecarboxylic acid, nicotinic acid, 2-chloronicotinic acid, 2-fluoronicotinic acid acid, 5-fluoronicotinic acid and 6-fluoronicotinic acid to the sgvS mutant, respectively. The fermentation extracts were analyzed by HPLC.
Results: sgvS mutant abolished the viridogrsein production; viridogrsein production was restored through in trans complementation of sgvS mutant or by feeding 3-hydroxypicolinic acid to the sgvS mutant. No new viridogrsein analogues were observed by feeding other above mentioned 3-hydroxypicolinic acid analogues tothe deltasgvS mutant.
Conclusion: sgvS is necessary for the biosynthesis of 3-hydroxypicolinic acid moiety. The biosynthetic protein, SgvD1, activates 3-hydroxypicolinic acid, showing strict substrate specificity en route to the viridogrsein biosynthesis.