The response of Trypanosoma brucei to Exogenous Fatty Acids in Low Lipid Conditions

Abstract

Trypanosoma brucei is an extracellular parasite that causes African Sleeping Sickness and is endemic to the sub-Saharan African region. The parasite's extracellular nature forces the parasite to adapt to its host's environment. One of the regulatory mechanisms is to regulate fatty acid synthesis enzymes in response to exogenous fatty acids. Our previous study showed that the insect-host procyclic form (PF) T. brucei regulates the activity and expression level of acetyl-CoA carboxylase (ACC) when grown in media containing different lipid levels. PF in low lipid media has an elevated ACC activity but lower ACC protein level than in high lipid media. We also observed that the addition of C18:0 to PF in low lipid media reduced ACC activity and increased growth rate, which showed an environmental response to the exogenous fatty acid level. Here, we observe the growth and the ACC level of low lipid-adapted PF T. brucei after treatment with fatty acids of different chain lengths. We did not observe a significant change in the ACC protein level. However, we observed significant growth differences with the addition of different fatty acids, and some of these effects were cell density-dependent. These data suggested that the addition of fatty acids changes ACC's activity and PF growth pattern in low lipid, but does not change PF's ACC expression level. Future studies will investigate whether different fatty acids regulate ACC activity by phosphorylation, allosteric regulation, or a combination of both mechanisms.