Characterization of a novel separase-interacting protein and candidate new securin, Eip1p, in the fungal pathogen Candida albicans

Abstract

Proper chromosome segregation is crucial for maintaining genomic stability and dependent on separase, a conserved and essential cohesin protease. Securins are key regulators of separases, but remain elusive in many organisms due to sequence divergence. Here, we demonstrate that the separase homologue Esp1p in the ascomycete Candida albicans, an important pathogen of humans, is essential for chromosome segregation . However, C. albicans lacks a sequence homologue of securins found in model ascomycetes. We sought a functional homologue through identifying Esp1p interacting factors. Affinity purification of Esp1p and mass spectrometry revealed Esp1p-Interacting Protein1 (Eip1p)/Orf19.955p, an uncharacterized protein specific to Candida species. Functional analyses demonstrated that Eip1p is important for chromosome segregation but not essential, and modulated in an APCCdc20-dependent manner, similar to securins. Eip1p is strongly enriched in response to methyl methanesulfate (MMS) or hydroxyurea (HU) treatment, and its depletion partially suppresses an MMS or HU-induced metaphase block. Further, Eip1p depletion reduces Mcd1p/Scc1p, a cohesin subunit and separase target. Thus, Eip1p may function as a securin. However, other defects in Eip1p-depleted cells suggest additional roles. Overall, the results introduce a candidate new securin, provide an approach for identifying these divergent proteins, reveal a putative anti-fungal therapeutic target, and highlight variations in mitotic regulation in eukaryotes.

Loss of Arp1, a putative actin-related protein, triggers filamentous and invasive growth and impairs pathogenicity in Candida albicans

“…Spindle morphology assays were performed as previously described [32] . Generally, overnight cells were collected and fixed with 70% ethanol for 5 min, washed twice with 1 × PBS, incubated in 1.0 μg/ml DAPI for 10 min, and then washed twice with 1 × PBS before being mounted for analysis.…”

Associations between Genomic Variants and Antifungal Susceptibilities in the Archived Global Candida auris Population

“…This SNP resulted in a Tyr236His mutation in the product of the gene B9J08_001308. Its ortholog EIP1 encodes a separase-binding protein in C. albicans and has been implicated in regulating the cell wall integrity, filamentation, and response to antifungals in C. albicans [39].…”