Carnitine suppression of position-effect variegation in Drosophila melanogaster

Carnitine is a well-known naturally occurring compound, very similar to butyrate, with an essential role in intermediary metabolism mainly at the mitochondrial level. Since butyrate inhibits the enzyme histone deacetylase and is capable of suppressing position-effect variegation in Drosophila melanogaster, we tested a further possible function of carnitine in the nucleus, using an assay for the suppression of position-effect variegation. We tested three physiological forms of carnitine (l-carnitine, l-propionylcarnitine, l-acetylcarnitine) for the ability to suppress two different chromosomal rearrangements, inducing variegation of the white⁺ and brown⁺ genes. The results show that the carnitine derivatives are capable of suppressing the position-effect variegation, albeit with different efficiencies. The carnitine derivatives interact lethally with Su-var(2)1⁰¹, a mutation that induces hyperacetylation of histones, whilst hyperacetylated histories accumulated in both the nuclei of HeLa cells and Drosophila polytene chromosomes treated with the same compounds. These results strongly suggest that the carnitine derivatives suppress position-effect variegation by a mechanism similar to that of butyrate. It is suggested that carnitines may have a functional role in the nucleus, probably at the chromatin level.