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Medientyp:
E-Artikel
Titel:
Robust Utilization of Phospholipase-Generated Metabolites, Glycerophosphodiesters, by Candida albicans: Role of the CaGit1 Permease
Beteiligte:
Bishop, Andrew C.;
Sun, Tao;
Johnson, Mitchell E.;
Bruno, Vincent M.;
Patton-Vogt, Jana
Erschienen:
American Society for Microbiology, 2011
Erschienen in:Eukaryotic Cell
Sprache:
Englisch
DOI:
10.1128/ec.05160-11
ISSN:
1535-9778;
1535-9786
Entstehung:
Anmerkungen:
Beschreibung:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Glycerophosphodiesters are the products of phospholipase-mediated deacylation of phospholipids. In
<jats:named-content content-type="genus-species">Saccharomyces cerevisiae</jats:named-content>
, a single gene,
<jats:italic>GIT1</jats:italic>
, encodes a permease responsible for importing glycerophosphodiesters, such as glycerophosphoinositol and glycerophosphocholine, into the cell. In contrast, the
<jats:named-content content-type="genus-species">Candida albicans</jats:named-content>
genome contains four open reading frames (ORFs) with a high degree of similarity to
<jats:named-content content-type="genus-species">S. cerevisiae</jats:named-content>
<jats:italic>GIT1</jats:italic>
(
<jats:italic>ScGIT1</jats:italic>
) Here, we report that
<jats:named-content content-type="genus-species">C. albicans</jats:named-content>
utilizes glycerophosphoinositol (GroPIns) and glycerophosphocholine (GroPCho) as sources of phosphate at both mildly acidic and physiological pHs. Insertional mutagenesis of
<jats:named-content content-type="genus-species">C. albicans</jats:named-content>
<jats:italic>GIT1</jats:italic>
(
<jats:italic>CaGIT1</jats:italic>
) (orf19.34), the ORF most similar to
<jats:italic>ScGit1</jats:italic>
, abolished the ability of cells to use GroPIns as a phosphate source at acidic pH and to transport [
<jats:sup>3</jats:sup>
H]GroPIns at acidic and physiological pHs, while reintegration of a
<jats:italic>GIT1</jats:italic>
allele into the genome restored those functions. Several lines of evidence, including the detection of internal [
<jats:sup>3</jats:sup>
H]GroPIns, indicated that GroPIns is transported intact through CaGit1. GroPIns transport was shown to conform to Michaelis-Menten kinetics, with an apparent
<jats:italic>
K
<jats:sub>m</jats:sub>
</jats:italic>
of 28 ± 6 μM. Notably, uptake of label from [
<jats:sup>3</jats:sup>
H]GroPCho was found to be roughly 50-fold greater than uptake of label from [
<jats:sup>3</jats:sup>
H]GroPIns and roughly 500-fold greater than the equivalent activity in
<jats:italic>S. cerevisiae.</jats:italic>
Insertional mutagenesis of
<jats:italic>CaGIT1</jats:italic>
had no effect on the utilization of GroPCho as a phosphate source or on the uptake of label from [
<jats:sup>3</jats:sup>
H]GroPCho. Growth under low-phosphate conditions was shown to increase label uptake from both [
<jats:sup>3</jats:sup>
H]GroPIns and [
<jats:sup>3</jats:sup>
H]GroPCho. Screening of a transcription factor deletion set identified
<jats:italic>CaPHO4</jats:italic>
as required for the utilization of GroPIns, but not GroPCho, as a phosphate source.
</jats:p>