Proteome analysis reveals differential expression of proteins involved in triacylglycerol accumulation by Rhodococcus jostii RHA1 after addition of methyl viologen.

DÁVILA COSTA J.; SILVA RA; LEICHERT L.; ALVAREZ HM

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Lugar: London; Año: 2017

1350-0872

Rhodococcus jostii RHA1 is able to degrade toxic compounds and accumulate high amount of triacylglycerols (TAG) upon nitrogen starvation. These NADPH-dependent processes are essential for the adaptation of rhodococci to fluctuating environmental conditions. In this study, we used a mass spectrometry (MS)-based, label-free, and quantitative proteomic approach to better understand the integral response of R. jostii RHA1 to the presence of methyl viologen (MV) in relation with the synthesis and accumulation of TAG. The addition of MV promoted a decrease of TAG accumulation in comparison to cells cultivated under nitrogen-limiting conditions in the absence of this pro-oxidant. Proteomic analyses revealed that the abundance of key proteins of fatty acid biosynthesis, the Kennedy pathway, glyceroneogenesis, and methylmalonyl-CoA pathway, among others, decreased in the presence of MV. In contrast, some proteins involved in lipolysis and β-oxidation of fatty acids were up-regulated. Some metabolic pathways linked to the synthesis of NADPH remained activated during oxidative stress as well as under nitrogen starvation conditions. Additionally, exposure to MV resulted in the activation of complete antioxidant machinery comprising of superoxide dismutases, catalases, mycothiol biosynthesis, mycothione reductase, alkyl hydroperoxide reductases, among others. Our study suggests that oxidative stress response affects TAG accumulation under nitrogen limiting conditions through programmed molecular mechanisms when both stresses occur simultaneously.