Candida albicans cis-prenyltransferase Rer2 is required for protein glycosylation, cell wall integrity and hypha formation

Abstract

Cis-prenyltransferase is the first enzyme of the mevalonate pathway committed to the biosynthesis of dolichol in eukaryotes. The RER2 gene encoding cis-prenyltransferase (Rer2p) in the human fungal pathogen Candida albicans was characterized. In addition, the ORF19.5236 encoding the second cis-prenyltransferase, which putatively is responsible for the synthesis of longer polyisoprenoids chains, was identified. When cultivated under repressive conditions, the conditional mutant strain expressing the RER2 gene from the regulatable MET3 promoter contained only 4% of cis-prenyltransferase activity and markedly diminished amounts of dolichols, as compared to the wild-type strain. Moreover, transcriptomal analyses revealed changes in the expression of 300 genes, mainly involved in transport, response to stress, filamentous growth and organelle organization. Growth of the conditional strain was blocked completely at 37 °C. The strain was hypersensitive to a wide range of inhibitors, which suggested glycosylation defects and compromised cell wall integrity. Moreover, the rer2 conditional mutant grown in the repressive conditions, unlike the same strain in the absence of repressor, failed to form hyphae. The results indicate that dolichols are essential not only for protein glycosylation and cell wall integrity but also for growth and development of C. albicans. Keywords protein glycosylation; dolichol; cis-prenyltransferase; Candida albicans; cell wall, hypha