Functional characterization of superoxide dismutase in Candida dubliniensis and effect of decyl methyl carbinol
Candida dubliniensis is a Candida species that is closely related to Candida albicans. Although they share high similarity in both genotypic and phenotypic characteristics including the capability to undergo mycelia transformation from yeast to hypha/pseudohyphae, C. dubliniensis is found to b...
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| Format: | Thesis |
| Language: | English |
| Published: |
2012
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/71519/1/FPSK%28M%29%202012%2056%20IR.pdf |
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| Summary: | Candida dubliniensis is a Candida species that is closely related to Candida albicans.
Although they share high similarity in both genotypic and phenotypic characteristics
including the capability to undergo mycelia transformation from yeast to
hypha/pseudohyphae, C. dubliniensis is found to be less virulent, more susceptible to
antifungal drugs and more sensitive to oxidative stress environment when compared to
C. albicans. Superoxide dismutase (Sod) is an important enzyme that disproportionates
superoxide free radical anions that are generated from oxidative stress. Although C.
dubliniensis consists of all the SOD ortholog sequences which have been found in C.
albicans, C. dubliniensis is unable to sustain significant growth at temperature higher
than 40°C when compared to C. albicans. Apart from that, quorum sensing molecule
(QSM) has been found to be proficient in suppressing morphological switching from
yeast to hyphal transition in both C. albicans and C. dubliniensis. Decyl methyl carbinol
(2-dodecanol), a recently identified QSM molecule that has been tested in C. albicans is
found to have suppressed the yeast to hyphal transformation in hyphal-induced condition.
2-dodecanol also found to suppress certain hyphal-specific genes (HSGs). The current
study is focused on the morphological changes of C. dubliniensis at different temperatures. The SOD genes in C. dubliniensis also have been sequenced and
characterized and the expression profile at 37°C and 42°C are studied in comparison to
C. albicans. The genes expression profiles were quantified using relative quantification
real time PCR. Two (2)-dodecanol was used to treat both C. dubliniensis and C. albicans.
The morphological transition, toxicity effect and growth rate in both C. dubliniensis &
albicans were recorded under the effect of 2-dodecanol. C. dubliniensis HSGs expression
profiles were recorded after exposing 2-dodecanol to C. dubliniensis under the hyphalinduced
condition. A clinical isolate that is isolated from University Malaya Medical
Centre was also molecularly characterized in this study. In the results, C. dubliniensis has
formed pseudohyphal at 42°C but unable to grow at temperatures higher than 42°C. The
SOD sequences from C. dubliniensis were posted with 85-95% similarity when aligned
with the orthologs sequences from C. albicans. Despite sharing a certain level of
similarities in the SOD sequences, a total of 5 SOD genes in C. dubliniensis were upregulated
in 42°C when compared to C. albicans that with only 2 SOD genes being upregulated.
This study discovers that, the over-expression of Sod in C. dubliniensis could
lead to the accumulations of high concentration of hydrogen peroxide and cause C.
dubliniensis unable to survive in high temperatures. 2-dodecanol, however, showed with
the effect to preserve both C. albicans and C. dubliniensis in round shaped yeast form.
Nevertheless, C. dubliniensis is significantly more sensitive to high concentration of 2-
dodecanol in terms of fungicidal and fungistatic effect. HSGs expression in C.
dubliniensis under the exposure to 2-dodecanol also vary from what has been seen in C.
albicans and constant expression of cdHSP90 can be the main factor that kept C.
dubliniensis in the yeast form. Interestingly, in this study, we also discovered that the
clinical isolate that resembled both C. dubliniensis & C. albicans are the potential interspecies
or intra-species between these two closely related species. |
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