Identification of an Exceptionally Long Intron in the HAC1 Gene of Candida parapsilosis

Abstract

The unfolded protein response (UPR) responds to the build-up of misfolded proteins in the endoplasmic reticulum. The UPR has wide-ranging functions from fungal pathogenesis to applications in biotechnology. The UPR is regulated through the splicing of an unconventional intron in the HAC1 gene. This intron has been described in many fungal species and is of variable length. Until now it was believed that some members of the CTG-Ser1 clade such as C. parapsilosis did not contain an intron in HAC1 , suggesting that the UPR was regulated in a different manner. Here we demonstrate that HAC1 plays an important role in regulating the UPR in C. parapsilosis . We also identified an unusually long intron (626 bp) in C. parapsilosis HAC1 . Further analysis showed that HAC1 orthologs in several species in the CTG-Ser1 clade contain long introns.