Immunomodulatory activities of <i>C. albicans</i>.

<p>Extracellular <i>C. albicans</i> inhibits complement deposition and detoxifies ROS via secreted mediators (SODs, catalase, Pra1), while phagocytosed cells proceed along an altered trafficking pathway to end up in an ER-associated compartment characterized by the membrane calnexin (Cnx) and a loss of LAMP-1, peripheral actin, and vATPase.</p

Morphogenesis of <i>C. albicans</i> within macrophages.

<p><i>C. albicans</i> cells constitutively expressing yCherry were incubated for one hour (top) or six hours (bottom). Germination is apparent early and has disrupted macrophage structures by the later time point.</p

Changes in <i>SKI7</i>, <i>HBS1</i>, and <i>PTC7</i> gene structure during fungal diversification.

<p><i>SKI7</i>, <i>HBS1</i> (A) and <i>PTC7</i> (B). See discussion for details. As in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003376#pgen-1003376-g001" target="_blank">Figure 1</a>, the alternative exon is indicated as a white box, while the upstream and downstream exons are indicated as grey and black boxes, respectively.</p

Some fungi use alternate methods to generate distinct <i>SKI7</i> and <i>HBS1</i> mRNAs from a single gene.

<p>Diagrammed are the gene structure of <i>Candida albicans</i> (A), <i>Cryptococcus neoformans</i> (B), and <i>Ustilago maydis</i> (C). Sequencing of rtPCR and 5′ RACE products confirms that <i>Candida albicans</i> generates distinct mRNAs through the use of alternative promoters, while EST sequences below the gene diagram show that basidiomycetes generates distinct mRNAs through exon skipping. As in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003376#pgen-1003376-g001" target="_blank">Figure 1</a>, the alternative exon is indicated as a white box, while the upstream and downstream exons are indicated as grey and black boxes, respectively.</p

The use of alternative 3′ splice sites in <i>SKI7/HBS1</i> is conserved in the two other subphyla of <i>Ascomycota</i>.

<p>Shown are schematics of the <i>SKI7/HBS1</i> gene of <i>Aspergillus nidulans</i> (A; a representative of the <i>Pezizomycotina</i>) and of <i>Saitoella complicata</i> (B; a representative of the <i>Taphrinomycotina</i>), along with parts of the sequencing results of rt-PCR products confirming use of alternative 3′ splice sites. As in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003376#pgen-1003376-g001" target="_blank">Figure 1</a>, the alternative exon is indicated as a white box, while the upstream and downstream exons are indicated as grey and black boxes, respectively.</p

The <i>SKI7/HBS1</i> gene in pre-whole-genome duplication <i>Saccharomycetaceae</i> encodes two different proteins.

<p> A: Shown is the structure of the <i>L. kluyveri</i> gene drawn to scale. Exon 1 is indicated as a grey box, the exon that is only included in the long splice isoform is indicated as a white box, and the sequence downstream of the distal 3′ splice site is indicated as a black box. The sequence logos depict alternative 3′ splice sites shared with five pre-WGD <i>Saccharomycetacea</i>e. B: Sequencing rtPCR products confirmed that both <i>L. kluyveri SKI7/HBS1</i> 3′ splice sites are used. C: Western blotting shows that translation of the two splice isoforms of <i>L. kluyveri SKI7/HBS1</i> results in two distinct proteins. The first lane is a control <i>S. cerevisiae</i> strain with its <i>SKI7</i> locus HA-tagged. The second, third and fourth lane contain plasmids with either an alternatively spliced <i>L. kluyveri SKI7/HBS1</i> gene, or a modified gene with the intron removed as indicated.</p

The <i>PTC7</i> gene is subfunctionalized through loss of alternative splicing in <i>Tetrapisispora blattae</i>.

<p>In <i>Saccharomyces cerevisiae</i> and most other <i>Saccharomycetaceae</i> the <i>PTC7</i> gene produces a nuclear envelope associated protein phosphatase through translation of the pre-mRNA and a mitochondrial protein phosphatase through translation of the spliced mRNA. In the post-WGD species <i>T. blattae</i>, both duplicated copies were maintained and one encodes a predicted nuclear envelope associated protein phosphatase, while the other encodes a predicted mitochondrial protein phosphatase.</p

The two proteins encoded by <i>L. kluyveri</i> SKI7/HBS1 are functional.

<p>A: As shown before, <i>L. kluyveri SKI7/HBS1</i> can complement both the temperature sensitive phenotype of <i>dcp1-2 ski7Δ</i> (compare rows 2 and 3). In contrast, a plasmid encoding only the long splice isoform complements <i>ski7Δ</i> (Row 4), but the short isoform does not. B: Conversely, the cold sensitive phenotype of <i>rps30AΔ hbs1Δ</i> is complemented by the short isoform, but not the long isoform C: The pre-WGD <i>Saccharomycetaceae SKI7/HBS1</i> genes encode both sequences conserved in post-WGD <i>SKI7</i> but not in post-WGD <i>HBS1</i> (indicated as motifs S1, S2, and S3) and sequences conserved in post-WGD <i>HBS1</i> (N-terminal domain encoded by exon 1 and a short sequence motif indicated as motif H1) but not in post-WGD <i>SKI7</i> genes.</p

<i>RCA1</i> is involved in growth, cell wall structure, filamentation and is regulated by CO₂.

<p><b>A</b>) Generation time in YPD of <i>C. albicans</i> (left panel) and <i>S</i>. <i>cerevisiae</i> (right panel) control strain (black columns) and <i>RCA1</i> ortholog mutants (white columns) grown in air or 5.5% CO₂ (grey columns). <b>B)</b> Germ tube formation in response to 5% serum of <i>C. albicans</i> control strain (black columns) and the <i>rca1</i>Δ (white columns) grown in air. <b>C</b>) Sensitivity assay of <i>C. albicans</i> control strain and <i>rca1</i>Δ. <b>D</b>) qRT-PCR using specific primers for Ca<i>RCA1</i> and <i>CST6</i> on RNA extracted from <i>C. albicans</i> (top) and <i>S. cerevisiae</i> (bottom) control strains, CAI4+pSM2 and BY4741, grown in air (black columns) or air enriched with 5.5% CO₂ (white columns). Data are represented as mean +/− SD. Asterisk indicates statistical significance determined by two-sample <i>t</i> test (<i>P</i>≤0.05).</p

Rca1p is associated to <i>NCE103</i> and cell wall structure genes.

<p><b>A</b>) Venn diagram of the Rca1p associated genes. <b>B</b>) Rca1p binds to the <i>NCE103</i> promoter. Representation of the normalized log₂-transformed signal intensities of RCA1-HA₃-tagged in air (top panel) and high CO₂ (bottom panel) compared to the untagged strain versus the corresponding position of each signal on <i>C. albicans</i> genomic regions. Log₂-transformed signal intensity values are indicated at the left of the <i>y</i>-axis, the reference is the value 0 (i.e., a binding ratio of 1). <b>C)</b> ChIP-qPCR of RCA1-HA₃ tagged strain versus untagged control in air and a 5.5% CO₂ environment normalized to <i>ACT1</i> level with primers designed to amplify the above identified binding region of Rca1p on the <i>NCE103</i> promoter. <b>D</b>) qRT-PCR carried out with primers for <i>C. albicans CHT2</i> (top) and <i>OCH1</i> (bottom) on total RNA extracted from the <i>C. albicans</i> control strain (black columns) and <i>rca1</i>Δ (white columns) grown in air. Data are represented as mean +/− SD. Asterisk indicates statistical significance determined by two-sample <i>t</i> test (<i>P</i>≤0.05).</p