How parasitic trypanosomes make the essential amino acid threonine in the tsetse fly

What is it about?

The amino acid threonine is essential for the synthesis of proteins and an important source of two carbon units for the synthesis of fatty acids and cholesterol-like molecules. Tsetse flies feed exclusively on blood, yet there is insufficient threonine to support the growth of their larval offspring. Tsetse flies have bacterial endosymbionts that retain the ability to either synthesise threonine or the precursor homoserine that may supply these nutrients to tsetse fly tissues and to the trypanosome. This article demonstrates that the trypanosome is capable of growth in the absence of threonine, provided either homoserine or bacterial signalling molecules called homoserine lactones are present in the growth medium.

Featured Image

Why is it important?

This investigation explains why this parasite has retained a biosynthetic pathway to convert homoserine (or homoserine lactones) into threonine and offers an explantion for why trypanosomes lacking endosymbionts become resistant to infection with trypanosomes. This may offer novel strategies to reduce transmission of the parasite between mamalain hosts.