Study of Two dagt Genes Involved in Triacylglycerols Biosynthesis in Rhodococcus opacus PD630

MARTIN HERNANDEZ, ANA ARABOLAZA, EDUARDO RODRÍGUEZ, HUGO GRAMAJO AND HECTOR ALVAREZ

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigadores en Bioquímica y Biología Molecular (SAIB); 2010

Purine metabolism in soil bacteria such as Streptomyces plays an important role in recycling nitrogen compounds from death organisms. However, only a parcial pathway for catabolism of GTP and ATP to allantoin has been reported. In this work we study a set of genes (sco6243, sco6247, sco6248) that is involved in the final conversion of allantoin to glyoxylate, ammonium and malate. In turn, we have also identified a negative transcriptional regulator for this set of genes, AllRStr, which is similar to the regulator protein of the allantoin pathway from E. coli, AllR. sco6243, sco6247 and sco6248 codify a putative malate syntase, allantoinase and allantoicase protein respectively. Growth analyses of mutant strains for each of these genes in minimal media containing purines or allantoin as the sole carbon and nitrogen source have demostrated that these genes are essencial for cell survival under these conditions. Inactivation of AllRStr increases the expression of allantoin pathway genes and strongly impairs antibiotic production. We are currently disrupting these genes in an allRStr mutant background to determine if impaired antibiotic production is due to the overexpression of this metabolic pathway. This results may well suggest that availability of precursors for synthesis of (p)ppGpp or acetyl-CoA are a check point for the production of secondary metabolites in Streptomyces.