Sequence analysis and immunofluorescence study of α- and β-tubulins inReticulomyxa filosa: Implications of the high degree of β2-tubulin divergence
✍ Scribed by Linder, Stefan ;Schliwa, Manfred ;Kube-Granderath, Eckhard
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 347 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0886-1544
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✦ Synopsis
We have cloned and sequenced 2 aand 2 b-tubulin isoforms from the giant freshwater amoeba Reticulomyxa filosa. The microtubules of this organism exhibit some unusual properties, including the highest rates of assembly and disassembly known and the inability to be stabilized by taxol. The cloned a-tubulins show a high degree of identity when compared to an a-tubulin consensus sequence. The b-tubulins, however, are more divergent, the b2-tubulin being the most unusual b-tubulin found so far. The deduced amino acid sequence of b2 shows 55% identity to a b-tubulin consensus sequence. It also features 51 unique exchanges which cluster in the C-terminal half of the molecule. Several unique exchanges and two insertions occur in regions adjacent to, or directly implicated in, conserved b-tubulin functions. A phylogenetic analysis places the b-tubulins of R. filosa in the vicinity of b-tubulins from fungi and slime molds. Monoclonal and polyclonal antibodies raised against R. filosa tubulins show that the electrophoretic mobility of aand b-tubulins is reversed with respect to tubulins from most other sources. Immunofluorescence experiments reveal a ubiquitous distribution of both b-tubulins in the amoebal network. Our observations suggest possible links between the aberrant primary structure of the b2-tubulin and the unusual properties of R. filosa microtubules.