Cyclopropane fatty acid synthesis affects cell shape and acid resistance in Leishmania mexicana

Abstract

Cyclopropane fatty acid synthase (CFAS) catalyzes the transfer of a methylene group from S-adenosyl methionine to an unsaturated fatty acid, generating a cyclopropane fatty acid (CFA). The gene encoding CFAS is present in many bacteria and several Leishmania spp. including Leishmania mexicana, Leishmania infantum and Leishmania braziliensis. In this study, we characterised the CFAS-null and -overexpression mutants in L. mexicana, the causative agent for cutaneous leishmaniasis in Mexico and central America. Our data indicate that L. mexicana CFAS modifies the fatty acid chain of plasmenylethanolamine (PME), the dominant class of ethanolamine glycerophospholipids in Leishmania, generating CFA-PME. While the endogenous level of CFA-PME is extremely low in wild type L. mexicana, overexpression of CFAS results in a significant increase. CFAS-null mutants (cfas) exhibit altered cell shape, increased sensitivity to acidic pH, and aberrant growth in serum-free media. In addition, the CFAS protein is preferentially expressed during the proliferative stage of L. mexicana and is required for the cell membrane targeting of lipophosphoglycan. Finally, the maturation and localization of CFAS protein are dependent upon the downstream sequence of the CFAS coding region. Without the downstream sequence, the mis-localised CFAS protein cannot fully rescue the defects of cfas. Our data suggest that CFA modification of phospholipids can significantly affect the parasite's response to certain adverse conditions. These findings are distinct from the roles of CFAS in L. infantum, highlighting the functional divergence in lipid modification among Leishmania spp.

Cyclopropane-Containing Fatty Acids from the Marine Bacterium Labrenzia sp. 011 with Antimicrobial and GPR84 Activity

“…Their modification, catalyzed by the CFAS enzymes, occurs in many bacteria and is recognized to play an important role in the adaptation of bacteria to drastic environmental perturbation such as acid or freeze-drying stress [ 49 , 50 ]. The cyclopropanation reaction of unsaturated lipids is well described for long chain fatty acids of M. tuberculosis and E. coli , and mainly associated with bacterial membranes [ 37 , 51 ]. In general, bacterial CFASs catalyze the transfer of a methyl group from SAM to an inactivated double bond of a lipid chain, followed by deprotonation of the newly attached methyl group and ring closure to form a cyclopropane ring [ 37 ].…”

Lipid and fatty acid metabolism in trypanosomatids

“…Genes involved in modification of FAs were also found in trypanosomatids genome databases, including those involved in the cyclopropanation [ 75 , 76 ] and synthesis of unsaturated FAs, which are FA molecules with one or more carbon-carbon double-bonds [ 77 , 78 ]. For instance, Leishmania spp., except L. major , encode a cyclopropane FA synthase (CFAS), whereas Trypanosoma lack this gene [ 76 ].…”

“…In eukaryotes, CFAS is responsible for the addition of a methylene group to carbon-carbon double-bonds of unsaturated FAs in membrane lipids, forming cyclopropane FA (CFA). CFAs synthesis was shown to affect the cellular shape of L. mexicana and its resistance to acidic environments, although CFAS knockout does not appear to have any impact on parasite infectivity [ 75 ]. In L. infantum promastigotes, on the other hand, absence of CFAS significantly decreased activity of membrane transporters and diminished parasite burdens in the spleen and liver during in vivo infection [ 76 ].…”

Cyclic Fatty Acids in Food: An Under-Investigated Class of Fatty Acids

“…Cyclopropane and the structurally related cyclopropene fatty acids have also been found in certain eukaryotes, including trypanosomatid protozoa and plants [19,20].…”