The atf2 gene is involved in triacylglycerol biosynthesis and accumulation in the oleaginous Rhodococcus opacus PD630

Abstract

Rhodococcus opacus PD630 is an oleaginous bacterium able to accumulate large amounts of triacylglycerols (TAG) in different carbon sources. The last reaction for TAG biosynthesis is catalyzed by the bifunctional wax ester synthase/acyl-CoA:diacylglycerol acyltransferase (WS/DGAT) enzymes encoded by atf genes. R. opacus PD630 possesses at least 17 putative atf homologous genes in its genome, but only atf1 and atf2 exhibited a significant DGAT activity when expressed in E. coli, as revealed in a previous study. The contribution of atf1 gene to TAG accumulation by strain PD630 has been demonstrated previously, although additional Atfs may also contribute to lipid accumulation, since the atf1-disrupted mutant is still able to produce significant amounts of TAG (Alvarez et al., Microbiology 154:2327-2335, 2008). In this study, we investigated the in vivo role of atf2 gene in TAG accumulation by R. opacus PD630 by using different genetic strategies. The atf2-disrupted mutant exhibited a decrease in TAG accumulation (up to 25-30 %, w/w) and an approximately tenfold increase in glycogen formation in comparison with the wild-type strain. Surprisingly, in contrast to single mutants, a double mutant generated by the disruption of atf1 and atf2 genes only showed a very low effect in TAG and in glycogen accumulation under lipid storage conditions. Overexpression of atf1 and atf2 genes in strain PD630 promoted an increase of approximately 10 % (w/w) in TAG accumulation, while heterologous expression of atf2 gene in Mycobacterium smegmatis caused an increase in TAG accumulation during cultivation in nitrogen-rich media. This study demonstrated that, in addition to atf1 gene, atf2 is actively involved in TAG accumulation by the oleaginous R. opacus PD630.

MAB_3551c encodes the primary triacylglycerol synthase involved in lipid accumulation in Mycobacterium abscessus

“…The amino acid sequence of MAB_3551c showed the highest percentage identity to the M. tuberculosis Tgs1, although all of the M. abscessus Tgs homologs shared relatively low primary sequence identity among each other as well as with M. tuberculosis Tgs1. High sequence dissimilarity was previously observed among other Ws/Dgat members (Hernández et al, ; Villa et al ., ; Alvarez, ). For simplicity, we defined MAB_3551c as Tgs1 in this study and categorized the remaining Tgs according to decreasing identity to MAB_3551c.…”

Integrated omics study delineates the dynamics of lipid droplets in Rhodococcus opacus PD630

“…Since TAG accumulates to high levels in MSM cultures, the increased expression of these four genes suggests that they may be involved in TAG synthesis. LPD05741, also named artf2 , had been verified to be involved in TAG biosynthesis and accumulation in PD630 (59). The elevation of LPD05741 is consistent with this study.…”

The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci

“…In the last years, several genes/proteins and their contributions on TAG metabolism have been well described in R. opacus PD630 or R. jostii RHA1 used as models. Examples of these studies include proteins such as diacylglycerol acyltransferase enzymes (DGAT) (Alvarez et al , ; Hernández et al ., ; Amara et al ), a NADPH‐dependent glyceraldehyde‐3‐phosphate dehydrogenase (TadD) (MacEachran and Sinskey, ), a phosphatidic acid phosphatase type 2 enzyme (PAP2) (Hernández et al ., ), an ATP‐binding cassette transporter (Lpt1) (Villalba and Alvarez, ) and structural proteins involved in lipid body ontogeny (TadA) (MacEachran et al , ; Ding et al , ). Besides enzymes, transporters and structural proteins, the TAG‐accumulating machinery of rhodococci may include an unknown regulatory network probably integrated by global and specific regulatory proteins, which could coordinate the transition to a TAG‐producing phenotype.…”