title: The costa of trichomonads: A complex macromolecular cytoskeleton structure made of uncommon proteins.
abstract: BACKGROUND
  The costa is a prominent striated fibre that is found in protozoa of the Trichomonadidae family that present an undulating membrane. It is composed primarily of proteins that have not yet been explored. In this study, we used cell fractionation to obtain a highly enriched costa fraction whose structure and composition was further analysed by electron microscopy and mass spectrometry.
  
  
  RESULTS
  Electron microscopy of negatively stained samples revealed that the costa, which is a periodic structure with alternating electron-dense and electron-lucent bands, displays three distinct regions, named the head, neck and body. Fourier transform analysis showed that the electron-lucent bands present sub-bands with a regular pattern. An analysis of the costa fraction via one- and two-dimensional electrophoresis and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) allowed the identification of 54 hypothetical proteins. Fourteen of those proteins were considered to be major components of the fraction.
  
  
  CONCLUSIONS
  The costa of T. foetus is a complex and organised cytoskeleton structure made of a large number of proteins which is assembled into filamentous structures. Some of these proteins exhibit uncharacterised domains and no function related according to gene ontology, suggesting that the costa structure may be formed by a new class of proteins that differ from those previously described in other organisms. Seven of these proteins contain prefoldin domains displaying coiled-coil regions. This propriety is shared with proteins of the striated fibres of other protozoan as well as in intermediate filaments.
  
  
  CONCLUSIONS
  Our observations suggest the presence of a new class of the cytoskeleton filaments in T. foetus. We believe that our data could auxiliate in determining the specific locations of these proteins in the distinct regions that compose the costa, as well as to define the functional roles of each component. Therefore, our study will help in the better understanding of the organisation and function of this structure in unicellular organisms.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Instituto Nacional de Metrologia, Qualidade e Tecnologia, Inmetro, Rio de Janeiro, Brazil.
authors.forename: Ivone
authors.initials: I
authors.lastname: de Andrade Rosa
authors.affiliation: Unidade de Espectrometria de Massas e Proteômica, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Marjolly Brigido
authors.initials: MB
authors.lastname: Caruso
authors.affiliation: Instituto Nacional de Metrologia, Qualidade e Tecnologia, Inmetro, Rio de Janeiro, Brazil.|UEZO-Universidade Estadual da Zona Oeste, Rio de Janeiro, Brazil.
authors.forename: Eidy
authors.initials: E
authors.lastname: de Oliveira Santos
authors.affiliation: Laboratório Nacional de Computação Cientifica (LNCC/MCT), Petrópolis, Rio de Janeiro, Brazil.
authors.forename: Luiz
authors.initials: L
authors.lastname: Gonzaga
authors.affiliation: Unidade de Espectrometria de Massas e Proteômica, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Instituto Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Russolina Benedeta
authors.initials: RB
authors.lastname: Zingali
authors.affiliation: Laboratório Nacional de Computação Cientifica (LNCC/MCT), Petrópolis, Rio de Janeiro, Brazil.
authors.forename: Ana Tereza R
authors.initials: ATR
authors.lastname: de Vasconcelos
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Instituto Nacional de Metrologia, Qualidade e Tecnologia, Inmetro, Rio de Janeiro, Brazil.|Instituto Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Instituto Nacional de Metrologia, Qualidade e Tecnologia, Inmetro, Rio de Janeiro, Brazil.|Instituto Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|UNIGRANRIO-Universidade do Grande Rio, Caxias, Rio de Janeiro, Brazil.
authors.forename: Marlene
authors.initials: M
authors.lastname: Benchimol
mesh_terms: D002458:Cell Fractionation; D003599:Cytoskeleton / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D053719:Tandem Mass Spectrometry; D016834:Trichomonadida / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D015800:Protozoan Proteins
keywords: Coiled-coils; Cytoskeleton; Mass spectrometry; Trichomonas vaginalis; Tritrichomonas foetus