Scientists stunned as bacteria rewire DNA machinery to shape cells

Ancient cyanobacteria repurpose DNA machinery into a cellular scaffold, revealing a fundamental evolutionary innovation in cell biology. | Contesto: cronaca

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• Scientists stunned as bacteria rewire DNA machinery to shape cells

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In a discovery that rewrites a chapter of fundamental biology, scientists have found that cyanobacteria, the ancient microbes responsible for oxygenating Earth's atmosphere, have repurposed a core molecular system once dedicated to separating DNA into a structure that physically shapes the cell itself. The finding, published this week, reveals a profound evolutionary innovation where a critical genetic apparatus was entirely retooled for a new, structural role billions of years after its origin. The research centers on a protein system long understood to be part of the cell's division machinery, specifically involved in partitioning replicated DNA strands into new daughter cells. In most organisms, this system's function is strictly confined to genetic segregation. However, detailed imaging and genetic analysis of modern cyanobacteria showed these proteins assembling into a completely different form: a dynamic, internal scaffold that dictates the cell's physical architecture. This scaffold appears to guide growth and maintain the cell's distinctive elongated, rod-like shape, a function wholly divorced from its ancestral DNA-handling duties. This repurposing represents a significant leap in our understanding of cellular evolution. Cyanobacteria are among the oldest life forms on the planet, with fossils dating back over 3.5 billion years. Their photosynthetic activity is credited with producing the oxygen that enabled the development of complex life. The discovery that they could so radically co-opt a fundamental system suggests a powerful and previously underappreciated evolutionary strategy. "It's like finding the engine of a car has been rebuilt into the frame of the chassis," explained one lead researcher on the project. "The components are the same, but their fundamental purpose in the machinery of life has been utterly transformed." The implications extend beyond a single microbial lineage. The study provides a concrete example of "molecular exaptation," a process where existing biological structures are hijacked for novel functions. This mechanism is a powerful driver of evolutionary complexity but is often difficult to trace in deep time. The...

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Categoria: cronaca