Activator-independent gene expression in Neurospora crassa Academic Article uri icon


  • A transgenic position effect that causes activator-independent gene expression has been described previously for three Neurospora crassa phosphate-repressible genes. We report analogous findings for two additional positively regulated genes, qa-2+ and ars-1+, indicating that such position effects are not limited to genes involved in phosphorus metabolism. In addition, we have characterized a number of mutants that display activator-independent gene expression. Each of these mutants contains a chromosomal rearrangement with one breakpoint located in the 5'-upstream region of the affected gene. This suggests that the rearrangements are associated with activator-independent gene expression and that these cis-acting mutations may represent a position effect similar to that responsible for rendering some transgenes independent of their transcriptional activators. We suggest that positively regulated genes in N. crassa are normally held in a transcriptionally repressed state by a cis-acting mechanism until specifically activated. Disruption of this cis-acting mechanism, either by random integration of a gene by transformation or by chromosomal rearrangement, renders these genes independent or partly independent of the transcriptional activator on which they normally depend.

author list (cited authors)

  • Versaw, W. K., & Metzenberg, R. L.

citation count

  • 4

complete list of authors

  • Versaw, WK||Metzenberg, RL

publication date

  • February 1996