Characterization of beta-oxidation pathway in Streptomyces coelicolor.

SIMON MENENDEZ-BRAVO, SANTIAGO COMBA, ANA ARABOLAZA AND HUGO GRAMAJO.

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular (SAIB).; 2012

Whilst the vast majority of bacteria synthesize polyhydroxyalkanoates as a carbon storage compound, actinomycetes have the almost unique capability of accumulate triacylglycerol (TAGs) in the form of lipid droplets. Utilization of stored TAGs involves the beta-oxidation of long chain fatty acids to generate acetyl-CoA. Nevertheless, there is no substantial information regarding genes involved in this process in actinomycetes. By means of methodical bioinformatics approaches using the genes fadA and fadB (coding for the fatty acid beta-oxidation complex) from E. coli as probe, we identified three genes coding for putatives fadB, each one associated to a putative fadA gene, suggesting the existence of three possible operons in Streptomyces coelicolor genome. We tested the capability of simple fadA and fadB knockout mutants to grow on fatty acids of different chain lengths as sole carbon and energy source and we observed no changes in growth rates compared to the wild type strain. However, there is a strong difference in TAG content in submerged liquid culture. While the wild type strain presents a marked depletion of the pool of TAGs at late-stationary phase of growth, this depletion is nearly inexistent in the mutant strains. Further construction and analysis of double and triple fadA/B mutants and analysis of expression profiles constitutes experimentation currently in course.