Iron Modulates Phenotypic Variation and Phosphorylation of P270 in Double-Stranded RNA Virus-Infected Trichomonas vaginalis

Abstract

Trichomonas vaginalis infected with a double-stranded RNA virus undergoes phenotypic variation on the basis of surface versus cytoplasmic expression of the immunogenic protein P270. Examination of batch cultures by flow cytofluorometry with monoclonal antibody (MAb) to P270 yields both fluorescent and nonfluorescent trichomonads. Greater numbers and intensity of fluorescent organisms with surface P270 reactive with MAb were evident in parasites grown in medium depleted of iron. Placement of iron-limited organisms in medium supplemented with iron gave increased numbers of nonfluorescent trichomonads. Purified subpopulations of trichomonads with and without surface P270 obtained by fluorescence-activated cell sorting reverted to nonfluorescent and fluorescent phenotypes when placed in high- and low-iron media, respectively. No similar regulation by iron of P270 was evident among virus-negative T. vaginalis isolates or virus-negative progeny trichomonads derived from virus-infected isolates. Equal amounts of P270 were detectable by MAb on immunoblots of total proteins from identical numbers of parasites grown in low- and high-iron media. Finally, P270 was found to be highly phosphorylated in high-iron parasites. Iron, therefore, plays a role in modulating surface localization of P270 in virus-harboring parasites.

Enzymes on microbial pathogens andTrichomonas vaginalis: molecular mimicry and functional diversity

“…1C). Further and as expected, the surface expression of P270, the phenotypically varying immunogen mentioned above, was readily detected for non‐permeabilized, low‐iron trichomonads, consistent with an earlier report (Alderete, 1999a). These results are consistent with the summary and published reports given above and reaffirm the surface expression of the SAEs characterized as trichomonad adhesins.…”

“…Four‐trichomonad surface proteins (referred to as AP65, AP51, AP33 and AP23 based on electrophoretic mobilities and collectively as AP proteins) were identified as mediating cytoadherence. Numerous established criteria (Beachey et al ., 1988) to show that the AP proteins were candidate adhesins were fulfilled (Arroyo et al , 1992; Alderete et al ., 1995a; Engbring et al ., 1996; Alderete, 1999a). (1) The proteins reside on the trichomonal surface as evidenced by surface radioiodination and indirect immunofluorescence experiments.…”

“…Controls included omission of the primary antibody followed by all treatments. Prior work has demonstrated the absence of any immunoreactivity with control hybridoma supernatant and normal rabbit serum (Arroyo et al , 1992, 1993, 1995; Alderete, O'Brien et al ., 1995, 1998; O'Brien et al ., 1996; Alderete, 1999).…”

Involvement of multiple DNA elements in iron‐inducible transcription of the ap65‐1 gene in the protozoan parasite Trichomonas vaginalis

“…It is likely that a signal cascade triggered by iron may induce nuclear expression of certain transcription factors, which may be integrated into the pre-existing transcription machinery involved in timely gene expression. As iron has also been shown to enhance protein phosphorylation (Alderete, 1999), it remains to be determined whether a common signal transduction pathway exists in the parasite to control expression of different iron-inducible genes.…”

Trichomonas vaginalisCysteine Proteinases: Iron Response in Gene Expression and Proteolytic Activity

“…PTMs play crucial roles in regulating the diverse protein-protein interactions involved in essentially every cellular process and therefore are required in every microorganism for its development. To date, PTM characterization in T. vaginalis has been reported for only a few proteins, for example, TveIF5a, cytoskeletal proteins, tubulin, and several virulence factors, P270, AP120, and TvCP39 [ 7 , 52 , 57 , 104 ].…”