[Polyketides--status and perspective]

The increased resistance among pathogenic bacteria is an important reason for research into new drugs and into improved efficiency of the ones already existing. A group of natural products, the polyketides, exhibits a range of antibiotic and other important pharmacological activities. This group of natural products has therefore attracted much attention from researchers world-wide. The biosynthesis of polyketides occurs in a stepwise fashion on gigantic multienzymes. Individual enzymatic entities within these multienzymes are responsible for catalysis of each step in the biosynthetic pathway of the polyketide chain. It has been demonstrated that there is a direct correlation between the DNA-sequence encoding these enzymatic units and the order in which the reactions are catalysed. Polyketide synthases may thus be considered a molecular assembly line, and new polyketides can be designed by changing the modules of the assembly line. An understanding of the rules governing the genetic manipulation of the synthases is of course of the utmost importance for success. The first major steps towards this goal have been taken with the results from a number of new experiments.