Fractals are abundant in nature, appearing in various forms such as river deltas and tree branches. These structures exhibit similarity when observed from a distance or upon closer examination. Among these fractals are regular fractals, which maintain identical patterns across different scales, including the spirals of
Romanesco cauliflower (SN: 7/8/21). However, regular fractals had not been observed in nature at the molecular level—until now.
In a study published on April 10 in Nature, evolutionary biochemist Georg Hochberg and colleagues reveal that a protein discovered in the bacterium Synechococcus elongatus
organizes itself into a fractal known as a Sierpiński triangle. When introduced into water, the proteins cluster together to form triangles composed of smaller triangles, comprising as many as 54 individual proteins, and potentially even more.
In the past, researchers have engineered synthetic molecules capable of forming regular fractals. However, the bacterial protein, known as citrate synthase, marks the first instance of such natural fractal elegance.
The scientists failed to discern any practical utility for the pattern and concluded it to be an evolutionary coincidence. Similar chance occurrences arise in other protein assemblies as well. "Various types of intricate structures emerge and disappear over evolutionary timescales, sometimes serving a purpose, sometimes not," notes Hochberg, hailing from the Max Planck Institute for Terrestrial Microbiology in Marburg, Germany. "Their symmetry can captivate us, leading us to believe they hold significance."
