NANOTECHNOLOGY is a hot topic in science. Not a day goes by without news of some clever device forged using components measuring billionths of a metre. But as is often the case, Mother Nature got there long before humans did. Living cells are nanotechnological factories of stunning complexity, containing the assembly lines, power stations, conveyor belts and control rooms necessary to keep life going.
This year’s Nobel prize in physiology or medicine has gone to three researchers who explained how one of these nanotechnological systems works. James Rothman, Randy Schekman and Thomas Südhof explained how cellular bodies called vesicles—little bubbles encased in fat—are used to ship hormones, enzymes and various other manufactured goods around a cell, and to export them to the outside world.
Dr Schekman’s work in the late 1970s explored the genetic mechanisms which control vesicle transport. He used genetic screening—a new-fangled technology at the time—to spot yeast cells whose transport systems were failing, causing jams in some parts of the cell and supply shortages in others. By compared the defective cells with properly functioning ones, Dr Schekman was able to isolate three different classes of genes, mutations in which caused the chaos.
Knowing how a piece of machinery can break down is important in understanding it. But so is knowing how it is meant to work. Dr Rothman discovered the molecular mechanism by which individual vesicles transport their cargoes to where they are needed, whether to other structures within a cell or through the cell wall to the outside. He discovered a pair of protein complexes, one on the vesicles and one set on their specific targets, that bind to each other like the two halves of a zip. If the proteins match, the vesicle opens and disgorges its cargo. If they do not, it remains shut.
Dr Südhof applied these insights to the specific question of how brain cells communicate. Nerve cells talk to each other with a mixture of electrical and chemical signals. When a neuron fires, an electrical impulse travels down its length until it reaches the synapse, the point at which one neuron joins with another. There, the electric signal stimulates the release of neurotransmitters, specialised molecules that cross the synaptic gap and stimulate the second neuron in turn. Dr Südhof described exactly how an arriving electrical impulse stimulates a rush of calcium ions into a cell, which subsequently causes vesicles loaded with neurotransmitters to bind to the cell wall, disgorging their contents across the gap.
Many of the journalists attending the prize ceremony seemed baffled by the details of the announcement. “You’re like Swedish undergrad students,” chided the committee, miffed by the lack of questions. The alternative explanation is that the hacks actually understood the science for once. After all the vesicle transport system described by the three laureates now features in cellular-biology textbooks the world over. It is vital for everything from cell division to the regulation of bodily systems through hormones. Diabetes, botulism and several neurological illnesses are at least partly the consequence of malfunctioning cellular logistics. Knowing how they run is the first step in designing treatments.
