title: Deletion of a novel protein kinase with PX and FYVE-related domains increases the rate of differentiation of Trypanosoma brucei.
abstract: Growth control of African trypanosomes in the mammalian host is coupled to differentiation of a non-dividing life cycle stage, the stumpy bloodstream form. We show that a protein kinase with novel domain architecture is important for growth regulation. Zinc finger kinase (ZFK) has a kinase domain related to RAC and S6 kinases flanked by a FYVE-related zinc finger and a phox (PX) homology domain. To investigate the function of the kinase during cyclical development, a stable transformation procedure for bloodstream forms of differentiation-competent (pleomorphic) Trypanosoma brucei strains was established. Deletion of both allelic copies of ZFK by homologous recombination resulted in reduced growth of bloodstream-form parasites in culture, which was correlated with an increased rate of differentiation to the non-dividing stumpy form. Growth and differentiation rates were returned to wild-type level by ectopic ZFK expression. The phenotype is stage-specific, as growth of procyclic (insect form) trypanosomes was unaffected, and Deltazfk/Deltazfk clones were able to undergo full cyclical development in the tsetse fly vector. Deletion of ZFK in a differentiation-defective (monomorphic) strain of T. brucei did not change its growth rate in the bloodstream stage. This suggests a function of ZFK associated with the trypanosomes' decision between either cell cycle progression, as slender bloodstream form, or differentiation to the non-dividing stumpy form.
authors.affiliation: Max-Planck-Institut für Biochemie, Am Klopferspitz 18a, 82152 Martinsried, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Vassella
authors.forename: R
authors.initials: R
authors.lastname: Krämer
authors.forename: C M
authors.initials: CM
authors.lastname: Turner
authors.forename: M
authors.initials: M
authors.lastname: Wankell
authors.forename: C
authors.initials: C
authors.lastname: Modes
authors.forename: M
authors.initials: M
authors.lastname: van den Bogaard
authors.forename: M
authors.initials: M
authors.lastname: Boshart
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins; D051381:Rats; D014346:Trypanosoma brucei brucei / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D014353:Trypanosomiasis, African / Q000469:parasitology; D016335:Zinc Fingers
chemical_list: D015800:Protozoan Proteins; C438379:ZFK protein, Trypanosoma brucei; D017346:Protein Serine-Threonine Kinases