CONTRIBUTION OF A SPECIFIC XRE TRANSCRIPTIONAL REGULATOR TO THE OLEAGINOUS PHENOTYPE IN RHODOCOCCI.

HERNANDEZ MA; LEDESMA A; ALVAREZ, H. M.

Buenos Aires

Congreso; LVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB), XVI Reunión Anual de la Sociedad Argentina de Microbiología General (SAMIGE); 2021

Oleagenicity is a property attributed to some microorganisms capable of accumulating high levels of intracellular lipids within the so-called lipid droplets (LDs). Some species of the Rhodococcus genus, such as R. opacus and R. jostii, are able to accumulate triacylglycerols (TAG) up to 60% or more of their cellular dry weight. For this reason, oleaginous rhodococci are promising microbial cell factories for the production of lipids to be used as fuels and oleochemicals. Although several genes involved in TAG biosynthesis and accumulation have been well described, it is not clear yet how these processes are regulated. In recent studies we have observed that some global and specific transcriptional regulators (TRs) contribute to the oleaginous phenotype in Rhodococcus. Between these TRs, three of them, known as GlnR, NlpR and TadR, act at different hierarchical levels and their mutation or overexpression significantly affected the TAG content in Rhodococcus. GlnR and NlpR act as putative global TRs, controlling a large set of genes associated with nitrogen, lipid and central metabolism. On the other side, TadR acts at a lower hierarchical level and regulates some specific genes associated with LDs ontogeny and lipid metabolism. Here, we presented some physiological and molecular evidences that confirm their roles on lipid accumulation in these bacteria and how is possible to deregulate this process for the optimization and recovery of these lipids. Based on these results, we proposed a comprehensive and integrative view on the regulatory attributes that explain the extraordinary capacity of these bacteria to synthesize and accumulate TAG at very high levels.