Candida Infection Biology – fungal armoury, battlefields ... - FINSysB

Poster number: 23
Fitness Profiling in Candida albicans by Systematic Gene
Overexpression
Sadri Znaidi 1,2 , Vitor Cabral 1,2 , Melanie Legrand 1,2 , Arnaud Firon 1 , Murielle
Chauvel 1 , Carol. A. Munro 3 and Christophe d’Enfert 1,2 .
1 Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et
Génétique, F-75015 Paris, France; 2 INRA, USC2019, F-75015 Paris, France; 3 School of
Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK
Background: Gene overexpression is a powerful strategy for mapping pathways
and phenotypes. It mimics gain-of-function mutations, complements loss-offunction
phenotypes and allows to study the function of both essential and non
essential genes. Because lack of a complete sexual cycle and aneuploidy hamper
the use of classical genetics in C. albicans, we hypothesized that combining gene
overexpression and strain barcoding would help in understanding gene function in
C. albicans.
Methods: Pools of 531 barcoded C. albicans strains, each overexpressing a unique
ORF under the control of a doxycycline (dox)-inducible promoter, were grown i) for
18 generations in rich medium in the absence or presence of dox or ii) in doxsupplemented
medium in the presence or absence of caspofungin (~IC 90% ). The
relative abundances of the strains were determined using barcode arrays. To
validate the microarray data, growth rates of the strains were measured individually,
using spot or liquid growth assays.
Results: We found 8 genes whose overexpression decreased C. albicans fitness in
rich medium by at least 1.5-fold (p