Doğal seçilim, rastlantı ve benzerlik eğilimi bakterilerin ürettiği bir böcek öldürücü molekül ailesini birlikte biçimlendiriyor

Many powerful antibiotics come from bacteria, and a large share belong to a family of molecules called nonribosomal peptides. These are built by enzyme complexes known as NRPS, which work like assembly lines, with separate modules adding amino acids one at a time. Unlike ordinary proteins, which change mainly through mutations in single DNA building blocks, these enzymes evolve by exchanging whole gene segments, a process called recombination. A team led by Helge Bode, whose group is at the Max Planck Institute for Terrestrial Microbiology, and Georg Hochberg of the University of Marburg studied GameXPeptides, insect-killing compounds made by bacteria that live inside nematodes. They identified 49 distinct variants and rebuilt the ancestral enzyme in E. coli. Their study shows that selection, random genetic drift and a bias towards recombining similar modules act together. This bias may explain why the same variants evolve again and again: they are easy to produce, rather than especially effective.