Tools for manipulation of secondary metabolism pathways: rapid promoter replacements and gene deletions in Aspergillus nidulans.

Targeted gene deletions and promoter replacements are proving to be a valuable tool for awakening and analyzing silent secondary metabolism gene clusters in Aspergillus nidulans and, as molecular genetic methods for manipulating the genomes of other fungi are developed, they will likely be as valuable in those organisms. Here we describe procedures for constructing DNA fragments by PCR that can be used to replace genes or promoters quickly and on a large scale. We also describe transformation procedures for A. nidulans that allow these fragments to be introduced into target strains efficiently such that many genes or promoters can be replaced in a single experiment.