Biosynthesis of 2‐Hydroxy and iso‐Even Fatty Acids is Connected to Sphingolipid Formation in Myxobacteria

Abstract

2-Hydroxy fatty acids can be found in several different organisms, including bacteria. In this study, we have studied the biosynthesis of 2-hydroxy fatty acids in the myxobacteria Myxococcus xanthus and Stigmatella aurantiaca, resulting in the identification of a family of stereospecific fatty acid alpha-hydroxylases. Although the stereospecificities of the hydroxylases differ between these two species, they share a common function in supporting fatty acid alpha-oxidation; that is, the oxidative shortening of fatty acids. Whereas in S. aurantiaca this process takes place during normal vegetative growth, in M. xanthus it takes place only under developmental conditions. We were also able to identify serine palmitoyltransferase encoding genes involved in sphingolipid biosynthesis as well as sphingolipids themselves in both types of myxobacteria, and were able to show that the alpha-hydroxylation reaction is in fact dependent on the presence of fatty acids bound to sphingolipids.

Identification of the phytosphingosine metabolic pathway leading to odd-numbered fatty acids

“…As the function of the DUF962 family has been elucidated here, we will refer to it as the Mpo1 family hereafter. Mpo1 family members exist in bacteria, fungi, plants and protists; 2-hydroxy FAs also exist in these organisms 20 , although its presence in protists has not been examined. It is therefore highly likely that Mpo1 family members are involved in the a-oxidation of 2-hydroxyacyl-CoAs in general.…”

“…Several organisms, including bacteria, fungi, plants and animals, possess 2-hydroxy FAs 20 . In mammals, 2-hydroxy FAs exist in specific tissues such as the epidermis, small intestine and in myelin 7,21,22 .…”

A comprehensive insight into the lipid composition of Myxococcus xanthus by UPLC-ESI-MS

“…A possible signaling function of PI-Cers in myxobacterial fruiting body formation or sporulation remains to be investigated. Although there have been no systematic investigations on putative signaling functions of Cers in bacteria, it was noted that sphingolipids (as determined by the sphingobases) accumulate in developing M. xanthus cells, but are dispensable for fruiting body formation ( 9 ).…”

“…ESI-MS data for the identifi cation and structure elucidation of PGs, PEs, and CLs, as well as glycerolipids (DGs and TGs) are also available (27)(28)(29)(30)(31)(32). The presence of PGs, PEs, and N -acylsphinganines (Cers), as well as the presence of distinctive ␣ -hydroxylated FAs together with the complete FA profi les of the investigated strains have been published ( 9,11,14,15 In general, isobaric molecular species could not be resolved by HPLC, and thus yielded one MS 2 spectra (see Tables 1, 3 ; supplementary Figs. I-VII ) For the creation of the lipid profi les, only the integrals from the negative ion mode for the PEs, PGs, PI-Cers, and Cers and from the positive ion mode for the DGs and TGs were used.…”

“…xanthus DK1622 wild-type and mutant strains were grown in 150 ml CTT media [10 g Casitone (Difco), 8 mM MgSO 4 , 1 mM K 2 HPO 4 , 10 mM Tris-HCl (pH 7.6)] supplemented with 40 g/ml kanamycin when appropriate at 30°C and 230 rpm on a rotary shaker in 1 l conical fl asks to an optical density of OD 600 ‫ف‬ 1.6. Strains ⌬ 0191, Ϫ MXAN_3748, and Ϫ MXAN_1528 are published elsewhere ( 9,12 ).…”