The SUN41 and SUN42 genes are essential for cell separation in Candida albicans.
Completion of the yeast cell cycle involves extensive remodelling of the cell wall upon separation of mother and daughter cells. We have studied two members of the ascomycete-specific SUN gene family in Candida albicans. Inactivation of SUN41 yields defects in cell separation and hyphal elongation while inactivation of SUN42 results in minor phenotypic alterations. Simultaneous inactivation of SUN41 and SUN42 is synthetically lethal due to lysis of mother cells after septation. Electronic microscopy reveals cell wall defects mainly localized in the region surrounding the septa. This phenotype is osmoremediable and the conditional double mutants show increased sensitivity to cell wall or cell membrane perturbing agents. The essential function shared by Sun41p and Sun42p is conserved among yeasts because UTH1, a Saccharomyces cerevisiae SUN gene, suppresses the lethality of SUN41 and SUN42 conditional mutants. Investigation of functional genomic data obtained in S. cerevisiae reveals links between members of the SUN gene family and the RAM pathway regulating cell wall-degrading enzymes specifically involved during cell separation. Thus, the main function of ascomycetous Sun proteins appears linked to cell wall remodelling, with a probable role in counter-balancing cell wall degradation to avoid cell lysis upon cell separation.
Firon
Arnaud
A
Unité Biologie et Pathogénicité Fongiques, INRA USC2019, Institut Pasteur, Paris, France.
Aubert
Sylvie
S
Iraqui
Ismaïl
I
Guadagnini
Stéphanie
S
Goyard
Sophie
S
Prévost
Marie-Christine
MC
Janbon
Guilhem
G
d'Enfert
Christophe
C
D002176:Candida albicans / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000648:ultrastructure; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D025301:Hyphae / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D008565:Membrane Proteins; D050296:Microbial Viability; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D018715:Microscopy, Video; D024101:Mitochondrial Proteins; D016254:Mutagenesis, Insertional; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology
D002352:Carrier Proteins; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; C116477:UTH1 protein, S cerevisiae