title: Functional analysis of the tubulin-folding cofactor C in Arabidopsis thaliana.
abstract: The biogenesis of microtubules comprises several steps, including the correct folding of alpha- and beta-tubulin and heterodimer formation. In vitro studies and the genetic analysis in yeast revealed that, after translation, alpha- and beta-tubulin are processed by several chaperonins and microtubule-folding cofactors (TFCs) to produce assembly-competent alpha-/beta-tubulin heterodimers. One of the TFCs, TFC-C, does not exist in yeast, and a potential function of TFC-C is thus based only on the biochemical analysis. In this study and in a very recently published study by Steinborn and coworkers, the analysis of the Arabidopsis porcino (por) mutant has shown that TFC-C is important for microtubule function in vivo. The predicted POR protein shares weak amino acid similarity with the human TFC-C (hTFC-C). Our finding that hTFC-C under the control of the ubiquitously expressed 35S promoter can rescue the por mutant phenotype shows that the POR gene encodes the Arabidopsis ortholog of hTFC-C. The analysis of plants carrying a GFP:POR fusion construct showed that POR protein is localized in the cytoplasm and is not associated with microtubules. While, in por mutants, microtubule density was indistinguishable from wild-type, their organization was affected.
authors.affiliation: University of Köln, Botanical Institute III, Gyrhofstr. 15, Germany.
authors.forename: Victor
authors.initials: V
authors.lastname: Kirik
authors.forename: Jaideep
authors.initials: J
authors.lastname: Mathur
authors.forename: Paul E
authors.initials: PE
authors.lastname: Grini
authors.forename: Irene
authors.initials: I
authors.lastname: Klinkhammer
authors.forename: Klaus
authors.initials: K
authors.lastname: Adler
authors.forename: Nicole
authors.initials: N
authors.lastname: Bechtold
authors.forename: Michel
authors.initials: M
authors.lastname: Herzog
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Bonneville
authors.forename: Martin
authors.initials: M
authors.lastname: Hülskamp
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D002455:Cell Division; D003001:Cloning, Molecular; D016384:Consensus Sequence; D019281:Dimerization; D017343:Genes, Plant; D005816:Genetic Complementation Test; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000648:ultrastructure; D008969:Molecular Sequence Data; D008970:Molecular Weight; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000502:physiology; D012098:Reproduction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014404:Tubulin / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D008869:Microtubule-Associated Proteins; C472495:POR protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D014404:Tubulin