Inhibition of polyamine synthesis arrests trichomonad growth and induces destruction of hydrogenosomes

Trichomonad parasites such as Tritrichomonas foetus produce large amounts o f putrescine (1,4-diaminobutane), which is transported out of the cell via an antiport mechanism which results in the uptake of a molecule of spermine . The importance of putrescine to the survival of the parasite and its role in the biology of T. foetus was investigated by use of the putrescine anal ogue 1,4-diamino-2-butanone (DAB). Growth of T. foetus in vitro was signifi cantly inhibited by 20 mM DAB, which was reversed by the addition of exogen ous 40 mM putrescine. High-performance liquid chromatography analysis of 20 mM DAB-treated T. foetus revealed that putrescine, spermidine, and spermin e levels were reduced by 89, 52, and 43%, respectively, compared to those i n control cells. The DAB treatment induced several ultrastructural alterati ons, which were primarily observed in the redox organelles termed hydrogeno somes. These organelles were progressively degraded, giving rise to large v esicles that displayed material immunoreactive with an antibody to P-succin yl-coenzyme A synthetase, a hydrogenosomal enzyme. A protective role for po lyamines as stabilizing agents in the trichomonad hydrogenosomal membrane i s proposed.