Overexpression of a phosphatidic acid phosphatase type 2 leads to an increase in triacylglycerols production in oleaginous Rhodococcus strains

MARTÍN A. HERNÁNDEZ, SANTIAGO COMBA, ANA ARABOLAZA, HUGO GRAMAJO, HÉCTOR M. ALVAREZ.

APPLIED MICROBIOLOGY AND BIOTECHNOLOGY

SPRINGER

Lugar: Berlin; Año: 2015 vol. 99 p. 2191 - 2207

0175-7598

Oleaginous Rhodococcus strains are able to accumulate large amounts oftriacylglycerols (TAG). Phosphatidic acid phosphatase enzyme (PAP) catalyzes thedephosphorylation of phosphatidic acid (PA) to yield diacylglycerol (DAG), a key precursor for TAG biosynthesis. Studies to establish its role in lipid metabolism have been mainly focused in eukaryotes but not in bacteria. In this work, we identified and characterized a putative PAP type 2 encoded by the ro00075 gene in R. jostii RHA1.Heterologous expression of ro00075 in E. coli resulted in an increase of four fold in thePAP activity and an increase of two fold in the DAG content. Conditional deletion of ro00075 gene in RHA1 led to a decrease of DAG and TAG contents, whereas its overexpression in strain RHA1 and R. opacus PD630 promoted an increase of 10 to 15% (by cellular dry weight) of TAG content. On the other hand, the expression of ro00075 gene in the non-oleaginous strain R. fascians F7 promoted an increase of 7 % of total fatty acid content at expenses of DAG and TAG fractions. Moreover, the coexpression of ro00075/atf2 genes resulted in an increase of four fold in the total fatty acid content at expenses of TAG fraction. The results of this study suggest that ro00075 gene encodes for a PAP2 enzyme actively involved in TAG biosynthesis. Overexpression of this gene, as single gene or with an atf gene, provides analternative approach to increase the biosynthesis and accumulation of bacterial oils as a potential source of raw material for biofuels production.