by PhilipJ on 28 June 2005
As Andre mentioned earlier the cytoskeleton in eukaryotic cells is composed of rodlike molecules, the αβ-tubulin. These microtubules are thought to be unique to higher organisms, and aren’t found in bacterial cells. Instead, bacterial cells have a homologue called FtsZ, which, while playing a similar role as the tubulin, is genetically and physically quite different.
Genomic analysis of Prosthecobacter dejongeii have revealed that BtubA and BtubB (for Bacterial tublin A/B), have a higher sequence similarity to eukaryotic αβ-tubulin. Structural studies show that while dimerization is weak and proper protein folding doesn’t require a chaperone (unlike eukaryotic tubulin), the physical structure is strikingly similar to their eukaryotic relative, including surface loops and forming protofilaments!
The paper concludes that horizontal gene transfer of one or possibly two tubulin genes from a higher organism into Prosthecobacter with subsequent sequence modification is the best explanation for the similarities observed. Cool!
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