The core components of organelle biogenesis and membrane transport in the hydrogenosomes of Trichomonas vaginalis

Trichomonas vaginalis is a parasitic protist of the Excavata group. It contains an anaerobic form of mitochondria called hydrogenosomes, which produce hydrogen and ATP; the majority of mitochondrial pathways and the organellar genome were lost during the mitochondrion-to-hydrogenosome transition. Consequently, all hydrogenosomal proteins are encoded in the nucleus and imported into the organelles. However, little is known about the membrane machineries required for biogenesis of the organelle and metabolite exchange. Using a combination of mass spectrometry, immunofluorescence microscopy, in vitro import assays and reverse genetics, we characterized the membrane proteins of the hydrogenosome. We identified components of the outer membrane (TOM) and inner membrane (TIM) protein translocases include multiple paralogs of the core Tom40-type porins and Tim17/22/23 channel proteins, respectively, and uniquely modified small Tim chaperones. The inner membrane proteins TvTim17/22/23-1 and Pam18 were shown to possess conserved information for targeting to mitochondrial inner membranes, but too divergent in sequence to support the growth of yeast strains lacking Tim17, Tim22, Tim23 or Pam18. Full complementation was seen only when the J-domain of hydrogenosomal Pam18 was fused with N-terminal region and transmembrane segment of the yeast homolog. Candidates for metabolite exchange across the outer membrane were identified including multiple isoforms of the β-barrel proteins, Hmp35 and Hmp36; inner membrane MCF-type metabolite carriers were limited to five homologs of the ATP/ADP carrier, Hmp31. Lastly, hydrogenosomes possess a pathway for the assembly of C-tail-anchored proteins into their outer membrane with several new tail-anchored proteins being identified. These results show that hydrogenosomes and mitochondria share common core membrane components required for protein import and metabolite exchange; however, they also reveal remarkable differences that reflect the functional adaptation of hydrogenosomes to anaerobic conditions and the peculiar evolutionary history of the Excavata group.     

Immunolocalization of tubulin isoforms and post-translational modifications in the protists Tritrichomonas foetus and Trichomonas vaginalis

In the present report we show the distribution of multiple tubulin isoforms in Trichomonas vaginalis and Tritrichomonas foetus, flagellated parasitic protists of the urogenital tracts of human and cattle, respectively, using immunofluorescence and immunoelectron microscopy. We used several monoclonal and polyclonal anti-tubulin antibodies from different sources and recognizing variant tubulin isoforms. Our results demonstrate that: (1) there is a heterogeneous distribution of the different tubulin isoforms in the main microtubular cell structures, such as axostyle, flagella, basal bodies, and mitotic spindle, (2) the axostyle-pelta junction is a structure with high affinity for glutamylated tubulin antibodies in T. foetus, (3) the spindle labeling is positive to anti-glutamylated tubulin and anti-alpha-tubulin (TAT1 and purchased from Amersham) antibodies in T. vaginalis but it is negative in T. foetus, (4) the nuclear matrix and the cytosol presented positive reaction using glutamylated and TAT1 (anti-alpha-tubulin) antibodies only in T. vaginalis, and (5) the Golgi complex exhibited staining using the glutamylated tubulin antibody. The present data corroborate with the idea of the existence of a heterogeneous population of microtubules in these protists and of a subset of intracytoplasmic microtubules. Microtubule diversity may reflect distinct tubulins, diverse microtubule-associated proteins, or a combination of both.     

The effect of hormones on Trichomonas vaginalis

The hormonal milieu can alter susceptibility to infection. The effect of hormones on Trichomonas vaginalis was studied utilizing axenically cultured clinical isolates. Oestrogens, in physiological concentrations, decreased the growth of the organisms and their attachment to mammalian cells in vitro, and acted as a chemorepellent. The specificity of these effects was verified by their being blocked with anti-oestrogens, by the dose- and time-dependency of the responses, and by the lack of effect with other hormones. These results suggest that oestrogens may decrease the virulence of T. vaginalis; however, interactions between oestrogens and mammalian cells may promote the development of infection. Thus complicated interactions between hormones, micro-organisms and mammalian cells must determine whether exposure to oestrogens predisposes to or prevents the development of infection.     

Freeze-fracture study of Trichomonas vaginalis

The freeze-fracture technique was used to analyse the organization of the plasma membrane, as well as membranes of cytoplasmic organelles, of the pathogenic protozoan Trichomonas vaginalis. Rosettes formed by 4 to 14 intramembranous particles were seen on the fracture faces of the membrane lining the anterior flagella as well as in fracture faces of the plasma membrane enclosing the anterior region of the protozoan and in cytoplasmic organelles. Special organization of the membrane particles were also seen in the region of association of the recurrent flagellum to the cell body.     

阴道毛滴虫染色体组型观察

采用火焰干燥法制备阴道毛滴虫染色体标本,按 Levan等方法,进行核型分析。阴道毛滴虫的染色体数目为n＝10,2n ＝20,染色体的组型为3m、3sm、1st和3T。 Abstract：　The chromosomes ofTrichomonas vaginaliswere prepared by flame-drying method. Data of chromosome were measured and calculated. According to Levan's method, analysis of karyotype was described. The results showed that the chromosome number ofT. vaginalisconsisted of twenty pairs(2n=20) and chromosome type was 3m, 3sm, 1st and 3T.     

阴道毛滴虫染色体组型观察

采用火焰干燥法制备阴道毛滴虫染色体标本,按 Levan等方法,进行核型分析。阴道毛滴虫的染色体数目为n＝10,2n ＝20,染色体的组型为3m、3sm、1st和3T。 Abstract：　The chromosomes ofTrichomonas vaginaliswere prepared by flame-drying method. Data of chromosome were measured and calculated. According to Levan's method, analysis of karyotype was described. The results showed that the chromosome number ofT. vaginalisconsisted of twenty pairs(2n=20) and chromosome type was 3m, 3sm, 1st and 3T.     

Polyamine biosynthesis and inhibition in Trichomonas vaginalis

Polyomines - particularly putrescine, spermidine and spermine - are ubiquitous components of eukaryote and most prokaryote cells, and are essential for optimal cell proliferation. But since routes of polyamine synthesis may differ, for example between parasites and their hosts, selective inhibition of polyamine metabolism offers an attractive target for chemotherapy - as already shown with the success of difluoromethylomithine (DFMO) as an inhibitor of polyamine synthesis in African trypanosomes. Parasitology Today has featured a series of articles reviewing research on polyamine metabolism of various parasites (eg. vol. 3, pp 190-192, pp 312-315; vol. 4, pp 18-20) and here, Nigel Yorlett discusses these metabolic aspects of Trichomonas vaginalis (Fig. 1)-a common parasite of the urogenital tract.     

Genetic identity and differential gene expression between Trichomonas vaginalis and Trichomonas tenax

Background  

Trichomonas vaginalis is a human urogenital pathogen responsible for trichomonosis, the number-one, non-viral sexually transmitted disease (STD) worldwide, while T. tenax is a commensal of the human oral cavity, found particularly in patients with poor oral hygiene and advanced periodontal disease. The extent of genetic identity between T. vaginalis and its oral commensal counterpart is unknown.