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IN BRIEF

PLP3 Proteins Function in Microtubule Assembly in Arabidopsis

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Phosphoducin-like protein1 (PLP1) in yeast has been shown to modulate the efficiency of β-tubulin and actin folding during mitosis. Homologs of PLP1, called PLP3, are highly conserved in other eukaryotes, including plants and animals, suggesting that they play an important role in development. In this issue, Castellano and Sablowski (pages 969–981) show that Arabidopsis PLP3 proteins associate with tubulin and are required for the production of functional microtubule arrays. Disruption of both genes via RNA inhibition (PLP3a) and T-DNA insertion (PLP3b) disrupted microtubule arrays in vivo and interfered with microtubule-dependent functions, including nuclear division, cytokinesis, and oriented cell expansion. The results suggest that PLP3 proteins play a role in chromosome segregation, cytokinesis, and directional cell expansion.

In animal cells, the spindle assembly checkpoint delays mitosis until all chromosomes are correctly attached to the mitotic spindle (Musacchio and Hardwick, 2002). Interestingly, the results of Castellano and Sablowski suggest that this type of a mitotic checkpoint may be irrelevant in shoot meristem cells, since the disruption of microtubule arrays in the PLP3-disrupted plants severely impacted cell division, but cells continued to cycle through DNA replication and abortive cytokinesis (see figure). Based on homology with yeast PLP1, Arabidopsis PLP3 proteins are likely involved in correct tubulin folding during microtubule assembly.

View larger version (69K): [in this window] [in a new window] [as a PowerPoint slide]   Floral meristems in PLP3-disrupted Arabidopsis plants produce enormous cells and develop abnormally. Optical sections through floral buds stained to show DNA (top panels) or cell walls (bottom panels) show irregularly shaped and grossly enlarged nuclei and formation of partial cell walls (arrows, bottom right), respectively. Bars = 20 µm (top) and 12.5 µm (bottom).

www.plantcell.org/cgi/doi/10.1105/tpc.108.200411

REFERENCES

Castellano, M.M., and Sablowski, R. (2008). Phosducin-like protein 3 is required for microtubule-dependent steps of cell division but not for meristem growth in Arabidopsis. Plant Cell 20: 969–981.[Abstract/Free Full Text]

Musacchio, A., and Hardwick, K.G. (2002). The spindle checkpoint: Structural insights into dynamic signalling. Nat. Rev. Mol. Cell Biol. 3: 731–741.[CrossRef][ISI][Medline]

Related articles in Plant Cell:

Phosducin-Like Protein 3 Is Required for Microtubule-Dependent Steps of Cell Division but Not for Meristem Growth in Arabidopsis

M. Mar Castellano and Robert Sablowski
Plant Cell 2008 20: 969-981. [Abstract] [Full Text]  

This Article Full Text (PDF) All Versions of this Article: 20/4/821    most recent tpc.108.200411v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Plant Cell Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Eckardt, N. A. Search for Related Content PubMed Articles by Eckardt, N. A. Agricola Articles by Eckardt, N. A.