Candida albicans Kar2 protein is essential and functions during the translocation of proteins into the endoplasmic reticulum

• Published in: Current genetics Vol. 57; no. 1; pp. 25 - 37
• Main Authors: Morrow, Michael W, Janke, Megan R, Lund, Kyle, Morrison, Emily P, Paulson, Benjamin A
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.02.2011; Springer-Verlag; Springer Nature B.V
• Subjects: Biochemistry; Biomedical and Life Sciences; Candida albicans; Candida albicans - genetics; Candida albicans - metabolism; Cell Biology; Endoplasmic Reticulum - metabolism; ER translocation; Fungal Proteins - genetics; Fungal Proteins - metabolism; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; KAR2; Life Sciences; Microbial Genetics and Genomics; Microbiology; Plant Sciences; Protein Transport; Proteomics; Research Article; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Secretory pathway; Translocation; Translocation assay; Translocation assay; Secretory pathway; ER translocation
• ISSN: 0172-8083; 1432-0983
• DOI: 10.1007/s00294-010-0323-1

Since the secretory pathway is essential for Candida albicans to transition from a commensal organism to a pathogen, an understanding of how this pathway functions may be beneficial for identifying novel drug targets to prevent candidiasis. We have cloned the C. albicans KAR2 gene, which performs many roles during the translocation of proteins into the endoplasmic reticulum (ER) during the first committed step of the secretory pathway in many eukaryotes. Our results show that C. albicans KAR2 is essential, and that the encoded protein rescues a temperature-sensitive growth defect found in a Saccharomyces cerevisiae strain harboring a mutant form of the Kar2 protein. Additionally, S. cerevisiae containing CaKAR2 as the sole copy of this essential gene are viable, and ER microsomes prepared from this strain exhibit wild-type levels of post-translational translocation during in vitro translocation assays. Finally, ER microsomes isolated from a C. albicans strain expressing reduced amounts of KAR2 mRNA are defective for in vitro translocation of a secreted substrate protein, establishing a new method to study ER translocation in this organism. Together, these results suggest that C. albicans Kar2p functions during the translocation of proteins into the ER during the first step of the secretory pathway.