In a simple way to great complexity

ETH microbiologists have succeeded in showing that nature produces one of the most complex known bioactive natural products in a staggeringly simple way. The molecule originates from bacteria living in sea sponges. In future, it may be possible to produce the agent very easily using biotechnology, making it an interesting avenue for cancer research. It is one of the most complex known naturally occurring peptides: a cytotoxic nanotube used by sea sponges living in the Pacific to defend themselves against other creatures. The agent is produced by bacteria that live in symbiosis with the sponges. As part of this process, the bacteria's protein-producing machinery first produces a precursor peptide, which is then modified at no fewer than 49 precisely defined locations by further bacterial enzymes (see box). These modifications determine the form and function of the peptide nanotube and improve its stability.