For the past couple years, biochemist Richard Ludueña has been in the grips of a compelling notion. “I’ve been working on tubulin my whole career,” says Ludueña, based at the University of Texas Health Science Center in San Antonio. “I’ve always wondered how it evolved.” Specifically, he’s been asking himself one question: What if a primitive form of that protein was one of the first proteins on earth, present in the primordial soup that gave rise to living organisms?
Until recently, tubulin, the building block of microtubules, was thought to be present only in eukaryotes. Ludueña’s theory hinges on a decade-old discovery that overturned that assumption: Folds in the crystal structure of a bacterial protein called FtsZ revealed that FtsZ and tubulin were phylogenetic cousins, sharing a common ancestor, despite their evolutionary distance (Nature, 391:203–6, 1998). All of this suggested that the protein was much older than many suspected. “That ...
