Complementary adhesin function in C. albicans biofilm formation.
BACKGROUND
Biofilms are surface-associated microbial communities with significant environmental and medical impact. Here, we focus on an adherence mechanism that permits biofilm formation by Candida albicans, the major invasive fungal pathogen of humans.


RESULTS
The Als surface-protein family has been implicated in biofilm formation, and we show that Als1 and Als3 have critical but redundant roles. Overexpression of several other Als proteins permits biofilm formation in a biofilm-defective als1/als1 als3/als3 strain, thus arguing that the function of Als proteins in this process is governed by their respective expression levels. The surface protein Hwp1 is also required for biofilm formation, and we find that a mixture of biofilm-defective hwp1/hwp1 and als1/als1 als3/als3 strains can form a hybrid biofilm both in vitro and in vivo in a catheter infection model. Complementary function of Hwp1 and Als1 and 3 seems to reflect their interaction because expression of Hwp1 in the heterologous host S. cerevisiae permits adherence to wild-type C. albicans, but not to an als1/als1 als3/als3 strain.


CONCLUSIONS
The complementary roles of Hwp1 and Als1 and Als3 in biofilm formation are analogous to the roles of sexual agglutinins in mating reactions. This analogy suggests that biofilm-adhesin complementarity may promote formation of monospecies biofilms.
Nobile
Clarissa J
CJ
Department of Microbiology, Columbia University, New York, New York 10032, USA.
Schneider
Heather A
HA
Nett
Jeniel E
JE
Sheppard
Donald C
DC
Filler
Scott G
SG
Andes
David R
DR
Mitchell
Aaron P
AP
D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D002176:Candida albicans / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D002177:Candidiasis / Q000209:etiology; D002405:Catheterization, Central Venous / Q000009:adverse effects; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000502:physiology*; D004195:Disease Models, Animal; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology; D009154:Mutation; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000502:physiology
C109455:ALA1 protein, Candida albicans; C093538:ALS1 protein, Candida albicans; C113620:ALS3 protein, Candida albicans; D015815:Cell Adhesion Molecules; D005656:Fungal Proteins; C118102:HWP1 protein, Candida albicans; D008562:Membrane Glycoproteins