Consequences of Neocentromere Formation In Candida albicans on Chromosome Segregation Accuracy and Drug Sensitivity

L. S. Burrack1, A. Plemmons2, A. Saha2, B. Turman3, J. Berman4

Author address: 

1Gustavus Adolphus Coll., Saint Peter, MN, 2Grinnell Coll., Grinnell, IA, 3Univ. of Minnesota, Minneapolis, MN, 4Tel Aviv Univ., Ramat Aviv, Israel

Abstract: 

Genome stability requires accurate chromosome segregation via assembly of a functional kinetochore at the centromere. Defects in chromosome segregation accuracy can cause DNA damage and chromosome rearrangements as well as aneuploidy, an imbalance in the numbers of individual chromosomes. In cancer cells and fungal pathogens, aneuploidy is linked with the development of drug resistance. However, high levels of genome instability can also sensitize cells to certain drugs and environmental stresses. Here, we used Candida albicans, fungi with small, epigenetically-inherited centromeres, as a model system to study how alteration of centromere position affected chromosome segregation accuracy and sensitivity to several classes of chemotherapy drugs and antifungal drugs. We constructed multiple strains where the native centromere was deleted and a neocentromere, or new centromere, assembled at different locus on chromosome 5. We then measured chromosome loss rates using a counter-selectable marker (URA3) and SNP-RFLP to confirm homozygosis of the remaining chromosome. All characterized neocentromeres mediated chromosome segregation, but some loci had up to 50- fold higher chromosome loss rates than others. For some stress treatments, there was no difference in the response of strains with native centromeres and neocentromeres. Elevated temperature and treatment with nicotinamide, an inhibitor of histone deacetylase activity, increased chromosome loss rates in all strains tested. Interestingly, treatment with radicicol, an inhibitor of Hsp90, had a greater effect on chromosome loss rates in the tested neocentromere strain compared to the control strain. We are currently expanding these studies to additional neocentromere strains and to additional antifungal and chemotherapy drugs to determine if strains with elevated chromosome loss rates are sensitized to drug treatment and/or if they differ in the frequency of drug resistant isolates.
2016

abstract No: 

FRIDAY-713

Full conference title: 

ASM Microbe 2016
    • ASM microbe 1st (2016)