Self-propagating organelle biogenesis on synthetic beads

How cells build their many organelles remains poorly understood. Centrosomes are a striking example: structurally complex organelles built from more than one hundred different proteins. Here we show that a synthetic bead can generate centrosome-like particles (CLiPs) in early Drosophila embryos if it is programmed to recruit any one of five essential centrosome assembly proteins. CLiPs behave remarkably like centrosomes: organising centrosomal proteins, microtubules and actomyosin, forming spindle poles, and undergoing multiple rounds of duplication - all in synchrony with the embryonic cell cycle. The beads generate CLiPs because they recruit Plk4, the master regulator of centrosome biogenesis, in a specific manner that stimulates its assembly activity. Thus, recruiting a single protein to a synthetic surface is sufficient to seed the self-assembly of a complex, self-propagating entity. These findings suggest a general framework for organelle biogenesis in which simple localised molecular inputs can seed the self-assembly of highly complex cellular structures.