Abstract:
The fungal pathogen Candida albicans is a leading causative agent of
death in immuno-compromised individuals. This pathogenicity involves, among
other, morphological switching from yeast to hyphal form. When filamentation is
induced, major structural and compositional alterations take place in the cell wall
affecting cell wall chitin content and cell wall proteome composition. Knockouts
of pir32, hwp2and pga1, three cell wall protein coding genes, have been
previously generated by homologous recombination of marker cassettes in our
lab. The purpose of this current study is to analyze the role these genes play by
comparing the cell wall composition of the mutant strains to the parental wild
type strain under both filamentous and non filamentous conditions. Cell wall
isolation and total cell wall protein content of these strains showed alterations in
the cell wall proteome. Chitin content was found to significantly decrease(50%) in
the pga1/pga1 mutant under non filamentous conditions, whereas in the
pir32/pi32 mutant, and under similar conditions, a 150% increase in chitin content
was recorded, an interesting result bearing in mind that chitin is a key player in
cell wall structure and rigidity. Total cell wall protein content ranged from a 50%
decrease in the pga1 null to a 50% increase in the pir32 mutant, implying
fundamental changes in the cell wall proteome. MALDI-TOF analysis showed
differential peptide mass fingerprints of cell wall proteins with many peaks found
to be unique to each mutant and to specific growth conditions. These peaks, when
entered into available databases, remained unidentified. As such, future work
requires analysis of these peaks by MS/MS peptide sequencing in an effort to
identify specific up or down regulated proteins represented by these peaks.
