Functional analysis of the tubulin-folding cofactor C in Arabidopsis thaliana.
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.
Kirik
Victor
V
University of Köln, Botanical Institute III, Gyrhofstr. 15, Germany.
Mathur
Jaideep
J
Grini
Paul E
PE
Klinkhammer
Irene
I
Adler
Klaus
K
Bechtold
Nicole
N
Herzog
Michel
M
Bonneville
Jean-Marc
JM
Hülskamp
Martin
M
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*
D029681:Arabidopsis Proteins; D008869:Microtubule-Associated Proteins; C472495:POR protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D014404:Tubulin