Centrin protein and genes in Trichomonas vaginalis and close relatives

Anti-centrin monoclonal antibodies 20H5 and 11B2 produced against Chlamydom onas centrin decorated the group of basal bodies as well as very closely at tached structures in all trichomonads studied and in the devescovinids Foai na and Devescovina. Moreover, these antibodies decorated the undulating mem brane in Trichomonas vaginalis, Trichomitus batrachorum, and Tritrichomonas foetus, and the cresta in Foaina. Centrin was not demonstrated in the divi ding spindle and paradesmosis. Immunogold labeling, both in pre- and post-e mbedding, confirmed that centrin is associated with the basal body cylinder and is a component of the nine anchoring arms between the terminal plate o f flagellar bases and the plasma-membrane. Centrin is also associated with the hook-shaped fibers attached to basal bodies (F1, F3), the X-fiber, and along sigmoid fibers (F2) at the pelta-axostyle junction, which is the micr otubule organizing center for pelta-axostyle microtubules. There was no lab eling on the striated costa and parabasal fibers nor on microtubular pelta- axostyle, but the fibrous structure inside the undulating membrane was labe led in T. vaginalis. Two proteins of 22-20 kDa corresponding to the centrin molecular mass were recognized by immunoblotting using these antibodies in the three trichomonad species examined. By screening a T. vaginalis cDNA library with 20H5 antibody, two genes enco ding identical protein sequences were found. The sequence comprises the 4 t ypical EF-hand Ca++ -binding domains present in every known centrin. Tricho monad centrin is closer to the green algal cluster (70% identity) than to t he yeast Cdc31 cluster (55% identity) or the Alveolata cluster (46% identit y).