Allantoin metabolism regulation by AllRStrep and its effect on antibiotic production in Streptomyces coelicolor

LAURA NAVONE, HUGO GRAMAJO AND EDUARDO RODRÍGUEZ

Rosario

Congreso; Reunión Anual de la Sociedad de Microbiología General (SAMIGE); 2013

Sociedad de Microbiología General

Streptomyces species are soil bacteria widely known as major producers of antibiotics and bioactive compounds. These bacteria are also characterized by a complex life cycle, including a programmed cell death (PCD) phenomena that allows cells to respond to a nutrient starvation period by committing ?partial? suicide and releasing essentials nutrients into the medium. Previous results indicated that the activation of the purine catabolic enzymes in coordination with the allantoin pathway during PCD allows the complete degradation of nucleotides into reduced carbon and nitrogen derivatives that can be uptaken easily by the ?surviving? population. Previous studies showed no feed-back inhibition on the allantoin pathway, so cells can degrade nucleotides into urea and ammonium and this has a negative effect on antibiotic production in Streptomcyes coelicolor. In this work we have identified AllRStrep as a regulatory protein that controls the allantoin regulon. The gene encoding this regulatory protein is next to allB-alC genes, enconding the allantoinase and allantoicase enzymes involved in the first two steps of allantoin degradation. Here using a combination of genetics and proteomics, we identified the allantoin regulon and other proteins that are up-regulated upon inactivation of AllRStrep. In vitro studies have confirmed that AllRStrep binds to the promoter regions of several genes encoding proteins of allantoin pathway. This allowed the identification of a putative consensus binding sequence. Effectors studies spotted out allantoic acid, the product of allantoinase, as a co-activator of the pathway suggesting a positive feed-back regulation of the pathway. Interestingly, inactivation of AllRStrep strongly impairs antibiotic production in S. coelicolor. Genetic studies suggested that up-regulation of hydroxypyruvate isomerase (Hyi) is responsible of the impairment of antibiotic production in the allRStrep- mutant strain. Together, these results expand our understanding of the relevance of primary metabolic pathways and the connection with secondary metabolism in Streptomyces. How the bacteria senses changes of primary metabolism intermediates and regulates antibiotic production is a great challenge that needs to be continued.