title: Glycogen accumulation and degradation by the trichomonads Trichomonas vaginalis and Trichomonas tenax.
abstract: Several species of trichomonad have been shown to accumulate significant quantities of glycogen during growth, suggesting an important role for this compound in cell physiology. We provide the first analysis of the changes in glycogen content and glycogen phosphorylase activity that occur during in vitro growth of two trichomonad species: Trichomonas vaginalis and Trichomonas tenax. Both species accumulated glycogen following inoculation into fresh medium and utilized this compound during logarithmic growth. Glycogen phosphorylase activity also varied during growth in a species-specific manner. The expression of phosphorylase genes in T. vaginalis remained constant during growth and thus transcriptional control did not explain the observed fluctuations in phosphorylase activity. After cloning, expression, and purification, two recombinant glycogen phosphorylases from T. vaginalis and one recombinant glycogen phosphorylase from T. tenax had robust activity and, in contrast to many other eukaryotic glycogen phosphorylases, did not appear to be regulated by reversible protein phosphorylation. Furthermore, allosteric regulation, if present, was not mediated by compounds known to impact the activity of better characterized phosphorylases.
authors.affiliation: Department of Microbiology & Immunology, Des Moines University, Des Moines, Iowa 50312, USA.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Nielsen
authors.forename: Prajakta
authors.initials: P
authors.lastname: Pradhan
authors.forename: Andrew
authors.initials: A
authors.lastname: Brittingham
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Wilson
mesh_terms: D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006003:Glycogen / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000378:metabolism; D014244:Trichomonas / Q000166:cytology* / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003470:Culture Media; D006003:Glycogen; D024981:Glycogen Phosphorylase