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

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Abstract

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.

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Acknowledgments

This research was funded by grant number P20 RR-16455-10 from the National Center for Research Resources (NCRR), a component of the National Institute of Health (NIH). We would like to thank Drs David Butler and Kurt Toenjes (Montana State University-Billings), Dr. Robert Cramer (Montana State University-Bozeman) and Dr. Jeffrey Brodsky (University of Pittsburgh) for providing strains, αScKar2p and αScSec61p antisera, qRT-PCR facility use, technical assistance and critically reviewing this manuscript. In addition, we also thank Drs Karen Arndt and Margaret Shirra (University of Pittsburgh) for assistance with tetrad dissections and Dr. Peter Sudbery (University of Sheffield) for providing plasmid pCaDis. Finally, we would like to thank Drs Qi Zhao and William C. Nierman (TIGR), Frank J. Smith and Aaron P. Mitchell (Carnegie Mellon University), and NIH grant 1R01AI057804 for the UAU1-containing clone, CAGA643.

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  1. Biology Department, The University of Montana Western, 710 South Atlantic Street, Dillon, MT, 59725, USA

    Michael W. Morrow, Megan R. Janke, Kyle Lund, Emily P. Morrison & Benjamin A. Paulson

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  1. Michael W. Morrow
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  2. Megan R. Janke
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  3. Kyle Lund
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Correspondence to Michael W. Morrow.

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Communicated by A. J. P. Brown.

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Morrow, M.W., Janke, M.R., Lund, K. et al. The Candida albicans Kar2 protein is essential and functions during the translocation of proteins into the endoplasmic reticulum. Curr Genet 57, 25–37 (2011). https://doi.org/10.1007/s00294-010-0323-1

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