scholarly journals Sep7 Is Essential to Modify Septin Ring Dynamics and Inhibit Cell Separation during Candida albicans Hyphal Growth

2008 ◽  
Vol 19 (4) ◽  
pp. 1509-1518 ◽  
Author(s):  
Alberto González-Novo ◽  
Jaime Correa-Bordes ◽  
Leticia Labrador ◽  
Miguel Sánchez ◽  
Carlos R. Vázquez de Aldana ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cell Separation ◽  
Hyphal Growth ◽  
Yeast Cells ◽  
Septin Ring ◽  
Protein Levels ◽  
Hyphal Morphogenesis ◽  
Hypha Formation ◽  
Ring Dynamics ◽  
Cytoskeleton Dynamics

When Candida albicans yeast cells receive the appropriate stimulus, they switch to hyphal growth, characterized by continuous apical elongation and the inhibition of cell separation. The molecular basis of this inhibition is poorly known, despite its crucial importance for hyphal development. In C. albicans, septins are important for hypha formation and virulence. Here, we used fluorescence recovery after photobleaching analysis to characterize the dynamics of septin rings during yeast and hyphal growth. On hyphal induction, septin rings are converted to a hyphal-specific state, characterized by the presence of a frozen core formed by Sep7/Shs1, Cdc3 and Cdc12, whereas Cdc10 is highly dynamic and oscillates between the ring and the cytoplasm. Conversion of septin rings to the hyphal-specific state inhibits the translocation of Cdc14 phosphatase, which controls cell separation, to the hyphal septum. Modification of septin ring dynamics during hyphal growth is dependent on Sep7 and the hyphal-specific cyclin Hgc1, which partially controls Sep7 phosphorylation status and protein levels. Our results reveal a link between the cell cycle machinery and septin cytoskeleton dynamics, which inhibits cell separation in the filaments and is essential for hyphal morphogenesis.

scholarly journals Candida albicans hyphal morphogenesis occurs in Sec3p-independent and Sec3p-dependent phases separated by septin ring formation

2007 ◽  
Vol 120 (11) ◽  
pp. 1898-1907 ◽  
Author(s):  
C.-R. Li ◽  
R. T.-H. Lee ◽  
Y.-M. Wang ◽  
X.-D. Zheng ◽  
Y. Wang
Keyword(s):  
Candida Albicans ◽  
Ring Formation ◽  
Septin Ring ◽  
Hyphal Morphogenesis

scholarly journals Zap1 Control of Cell-Cell Signaling in Candida albicans Biofilms

2011 ◽  
Vol 10 (11) ◽  
pp. 1448-1454 ◽  
Author(s):  
Shantanu Ganguly ◽  
Andrew C. Bishop ◽  
Wenjie Xu ◽  
Suman Ghosh ◽  
Kenneth W. Nickerson ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Yeast Cells ◽  
Gas Chromatography Mass Spectrometry ◽  
Wild Type ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Hypha Formation ◽  
Dependent Signal ◽  
Reporter Strains ◽  
Biosensor Strain

ABSTRACTBiofilms ofCandida albicansinclude both yeast cells and hyphae. Prior studies indicated that azap1Δ/Δ mutant, defective in zinc regulator Zap1, has increased accumulation of yeast cells in biofilms. This altered yeast-hypha balance may arise from internal regulatory alterations or from an effect on the production of diffusible quorum-sensing (QS) molecules. Here, we develop biosensor reporter strains that express yeast-specificYWP1-RFPor hypha-specificHWP1-RFP, along with a constitutiveTDH3-GFPnormalization standard. Seeding these biosensor strains into biofilms allows a biological activity assay of the surrounding biofilm milieu. Azap1Δ/Δ biofilm induces the yeast-specificYWP1-RFPreporter in a wild-type biosensor strain, as determined by both quantitative reverse transcription-PCR (qRT-PCR) gene expression measurements and confocal microscopy. Remediation of thezap1Δ/Δ zinc uptake defect through zinc transporter geneZRT2overexpression reverses induction of the yeast-specificYWP1-RFPreporter. Gas chromatography-mass spectrometry (GC-MS) measurements of known organic QS molecules show that thezap1Δ/Δ mutant accumulates significantly less farnesol than wild-type or complemented strains and thatZRT2overexpression does not affect farnesol accumulation. Farnesol is a well-characterized inhibitor of hypha formation; hence, a reduction in farnesol levels inzap1Δ/Δ biofilms is unexpected. Our findings argue that a Zap1- and zinc-dependent signal affects the yeast-hypha balance and that it is operative in the low-farnesol environment of thezap1Δ/Δ biofilm. In addition, our results indicate that Zap1 is a positive regulator of farnesol accumulation.

scholarly journals Candida albicans Rho-Type GTPase-Encoding Genes Required for Polarized Cell Growth and Cell Separation

2007 ◽  
Vol 6 (5) ◽  
pp. 844-854 ◽  
Author(s):  
Alexander Dünkler ◽  
Jürgen Wendland
Keyword(s):  
Cell Cycle ◽  
Candida Albicans ◽  
Cell Polarity ◽  
Cell Separation ◽  
Cycle Length ◽  
Hyphal Growth ◽  
Rho Proteins ◽  
Polarized Cell Growth ◽  
Bud Growth ◽  
Cell Cycle Length

ABSTRACT Rho proteins are essential regulators of morphogenesis in eukaryotic cells. In this report, we investigate the role of two previously uncharacterized Rho proteins, encoded by the Candida albicans RHO3 (CaRHO3) and CaCRL1/CaRHO4 genes. The CaRHO3 gene was found to contain one intron. Promoter shutdown experiments using a MET3 promoter-controlled RHO3 revealed a strong cell polarity defect and a partially depolarized actin cytoskeleton. Hyphal growth after promoter shutdown was abolished in rho3 mutants even in the presence of a constitutively active ras1(G13V) allele, and existing germ tubes became swollen. Deletion of C. albicans RHO4 indicated that it is a nonessential gene and that rho4 mutants were phenotypically different from rho3. Two distinct phenotypes of rho4 cells were elongated cell morphology and an unexpected cell separation defect generating chains of cells. Colony morphology of crl1/rho4 resulted in a growth-dependent smooth (long cell cycle length) or wrinkled (short cell cycle length) phenotype. This phenotype was additionally dependent on the rho4 cell separation defect and was also found in a Cacht3 chitinase mutant that shows a strong cytokinesis defect. The overexpression of the endoglucanase encoding the ENG1 gene, but not CHT3, suppressed the cell separation defect of crl1/rho4 but could not suppress the cell elongation phenotype. C. albicans Crl1/Rho4 and Bnr1 both localize to septal sites in yeast and hyphal cells but not to the hyphal tip. Deletion of RHO4 and BNR1 produced similar morphological phenotypes. Based on the localization of Rho4 and on the rho4 mutant phenotype, we propose a model in which Rho4p may function as a regulator of cell polarity, breaking the initial axis of polarity found during early bud growth to promote the construction of a septum.

scholarly journals Conjugated Linoleic Acid Inhibits Hyphal Growth in Candida albicans by Modulating Ras1p Cellular Levels and Downregulating TEC1 Expression

2011 ◽  
Vol 10 (4) ◽  
pp. 565-577 ◽  
Author(s):  
Julie Shareck ◽  
André Nantel ◽  
Pierre Belhumeur
Keyword(s):  
Candida Albicans ◽  
Linoleic Acid ◽  
Conjugated Linoleic Acid ◽  
Cellular Localization ◽  
Therapeutic Potential ◽  
Transcriptional Profiling ◽  
Hyphal Growth ◽  
Cellular Growth ◽  
Content Type ◽  
Protein Levels

ABSTRACTThe polymorphic yeastCandida albicansexists in yeast and filamentous forms. Given that the morphogenetic switch coincides with the expression of many virulence factors, the yeast-to-hypha transition constitutes an attractive target for the development of new antifungal agents. Since an untapped therapeutic potential resides in small molecules that hinderC. albicansfilamentation, we characterized the inhibitory effect of conjugated linoleic acid (CLA) on hyphal growth and addressed its mechanism of action. CLA inhibited hyphal growth in a dose-dependent fashion in both liquid and solid hypha-inducing media. The fatty acid blocked germ tube formation without affecting cellular growth rates. Global transcriptional profiling revealed that CLA downregulated the expression of hypha-specific genes and abrogated the induction of several regulators of hyphal growth, includingTEC1,UME6,RFG1, andRAS1. However, neitherUME6norRFG1was necessary for CLA-mediated hyphal growth inhibition. Expression analysis showed that the downregulation ofTEC1expression levels by CLA depended onRAS1. In addition, whileRAS1transcript levels remained constant in CLA-treated cells, its protein levels declined with time. With the use of a strain expressing GFP-Ras1p, CLA treatment was also shown to affect Ras1p localization to the plasma membrane. These findings suggest that CLA inhibits hyphal growth by affecting the cellular localization of Ras1p and blocking the increase inRAS1mRNA and protein levels. Combined, these effects should prevent the induction of the Ras1p signaling pathway. This study provides the biological and molecular explanations that underlie CLA's ability to inhibit hyphal growth inC. albicans.

A putative dual-specific protein phosphatase encoded by YVH1 controls growth, filamentation and virulence in Candida albicans

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2223-2232 ◽  
Author(s):  
Nozomu Hanaoka ◽  
Takashi Umeyama ◽  
Keigo Ueno ◽  
Kenji Ueda ◽  
Teruhiko Beppu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Candida Albicans ◽  
Cell Cycle Progression ◽  
Germ Tube ◽  
Hyphal Growth ◽  
Tube Formation ◽  
Yeast Cells ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Cycle Progression

In response to stimulants, such as serum, the yeast cells of the opportunistic fungal pathogen Candida albicans form germ tubes, which develop into hyphae. Yvh1p, one of the 29 protein phosphatases encoded in the C. albicans genome, has 45 % identity with the dual-specific phosphatase Yvh1p of the model yeast Saccharomyces cerevisiae. In this study, Yvh1p expression was not observed during the initial step of germ tube formation, although Yvh1p was expressed constitutively in cell cycle progression of yeast or hyphal cells. In an attempt to analyse the function of Yvh1p phosphatase, the complete ORFs of both alleles were deleted by replacement with hph200–URA3–hph200 and ARG4. Although YVH1 has nine single-nucleotide polymorphisms in its coding sequence, both YVH1 alleles were able to complement the YVH1 gene disruptant. The vegetative growth of Δyvh1 was significantly slower than the wild-type. The hyphal growth of Δyvh1 on agar, or in a liquid medium, was also slower than the wild-type because of the delay in nuclear division and septum formation, although germ tube formation was similar between the wild-type and the disruptant. Despite the slow hyphal growth, the expression of several hypha-specific genes in Δyvh1 was not delayed or repressed compared with that of the wild-type. Infection studies using mouse models revealed that the virulence of Δyvh1 was less than that of the wild-type. Thus, YVH1 contributes to normal vegetative yeast or hyphal cell cycle progression and pathogenicity, but not to germ tube formation.

scholarly journals Sch9 Kinase Integrates Hypoxia and CO2Sensing To Suppress Hyphal Morphogenesis in Candida albicans

2011 ◽  
Vol 10 (4) ◽  
pp. 502-511 ◽  
Author(s):  
Catrin Stichternoth ◽  
Alida Fraund ◽  
Eleonora Setiadi ◽  
Luc Giasson ◽  
Anna Vecchiarelli ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Wild Type Strain ◽  
Cell Wall Proteins ◽  
Content Type ◽  
Chronological Aging ◽  
Hyphal Morphogenesis ◽  
Hypha Formation ◽  
Virulence Trait ◽  
Genes Encoding ◽  
A Minor

ABSTRACTThe yeast-hypha transition is an important virulence trait ofCandida albicans. We report that the AGC kinase Sch9 prevents hypha formation specifically under hypoxia at high CO2levels.sch9mutants showed no major defects in growth and stress resistance but a striking hyperfilamentous phenotype under hypoxia (<10% O2), although only in the presence of elevated CO2levels (>1%) and at temperatures of <37°C during surface growth. Thesch9hyperfilamentous phenotype was independent of Rim15 kinase and was recreated by inhibition of Tor1 kinase by rapamycin or caffeine in a wild-type strain, suggesting that Sch9 suppression requires Tor1. Caffeine inhibition also revealed that both protein kinase A isoforms, as well as transcription factors Czf1 and Ace2, are required to generate thesch9mutant phenotype. Transcriptomal analyses showed that Sch9 regulates most genes solely under hypoxia and in the presence of elevated CO2. In this environment, Sch9 downregulates genes encoding cell wall proteins and nutrient transporters, while under normoxia Sch9 and Tor1 coregulate a minor fraction of Sch9-regulated genes, e.g., by inducing glycolytic genes. Other than inSaccharomyces cerevisiae, bothsch9andrim15mutants showed decreased chronological aging under normoxia but not under hypoxia, indicating significant rewiring of the Tor1-Sch9-Rim15 pathway inC. albicans. The results stress the importance of environmental conditions on Sch9 function and establish a novel response circuitry to both hypoxia and CO2inC. albicans, which suppresses hypha formation but also allows efficient nutrient uptake, metabolism, and virulence.

scholarly journals Candida albicans Ubiquitin and Heat Shock Factor-Type Transcriptional Factors Are Involved in 2-Dodecenoic Acid-Mediated Inhibition of Hyphal Growth

2020 ◽  
Vol 8 (1) ◽  
pp. 75
Author(s):  
Dongliang Yang ◽  
Yanling Hu ◽  
Zixin Yin ◽  
Qianru Gao ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Hyphal Growth ◽  
Filamentous Growth ◽  
Burkholderia Cenocepacia ◽  
Hyphal Morphogenesis ◽  
Expression Of Genes ◽  
Exogenous Addition ◽  
Diffusible Signal Factor ◽  
Factor Type ◽  
Hyphal Formation

Cis-2-dodecenoic acid (i.e., Burkholderia cenocepacia Diffusible Signal Factor, BDSF), a signaling molecule produced by Burkholderia cenocepacia but not by Candida albicans, can prevent Candida albicans hyphal formation. The mechanism by which BDSF controls the morphological switch of C. albicans is still unknown. To address this issue, we used the cDNA microarray method to investigate the differential expression of genes in C. albicans in the presence and absence of BDSF. The microarray result indicated that 305 genes were significantly different in the expression level. This included the downregulation of 75 genes and the upregulation of 230 genes. Based on the microarray data, a mutant library was screened to search for genes, once mutated, conferred insensitivity to BDSF. The results showed that the repressors (Ubi4 and Sfl1 proteins) and the activator (Sfl2 protein) of filamentous growth are involved in the BDSF regulation of hyphal morphogenesis. Ubi4, an ubiquitin polypeptide that participates in ubiquitin-mediated protein turnover, is the protein required for the degradation of Sfl2. Sfl1 and Sfl2 proteins antagonistically control C. albicans morphogenesis. In the hyphal induction condition, the amount of Ubi4 and Sfl1 protein increased rapidly with the exogenous addition of BDSF. As a result, the protein level of the activator of filamentous growth, Sfl2, decreased correspondingly, thereby facilitating the C. albicans cells to remain in the yeast form.

scholarly journals Role of Transcription Factor CaNdt80p in Cell Separation, Hyphal Growth, and Virulence in Candida albicans

2010 ◽  
Vol 9 (4) ◽  
pp. 634-644 ◽  
Author(s):  
Adnane Sellam ◽  
Christopher Askew ◽  
Elias Epp ◽  
Faiza Tebbji ◽  
Alaka Mullick ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Cell Separation ◽  
Hyphal Growth ◽  
Functional Domain ◽  
Transcription Factor Family ◽  
Content Type ◽  
Genes Encoding

ABSTRACT The NDT80/PhoG transcription factor family includes ScNdt80p, a key modulator of the progression of meiotic division in Saccharomyces cerevisiae. In Candida albicans, a member of this family, CaNdt80p, modulates azole sensitivity by controlling the expression of ergosterol biosynthesis genes. We previously demonstrated that CaNdt80p promoter targets, in addition to ERG genes, were significantly enriched in genes related to hyphal growth. Here, we report that CaNdt80p is indeed required for hyphal growth in response to different filament-inducing cues and for the proper expression of genes characterizing the filamentous transcriptional program. These include noteworthy genes encoding cell wall components, such as HWP1, ECE1, RBT4, and ALS3. We also show that CaNdt80p is essential for the completion of cell separation through the direct transcriptional regulation of genes encoding the chitinase Cht3p and the cell wall glucosidase Sun41p. Consistent with their hyphal defect, ndt80 mutants are avirulent in a mouse model of systemic candidiasis. Interestingly, based on functional-domain organization, CaNdt80p seems to be a unique regulator characterizing fungi from the CTG clade within the subphylum Saccharomycotina. Therefore, this study revealed a new role of the novel member of the fungal NDT80 transcription factor family as a regulator of cell separation, hyphal growth, and virulence.

Identification of the dialysable serum inducer of germ-tube formation in Candida albicans

Microbiology ◽  
2004 ◽  
Vol 150 (9) ◽  
pp. 3041-3049 ◽  
Author(s):  
Debbie A. Hudson ◽  
Quentin L. Sciascia ◽  
Rebecca J. Sanders ◽  
Gillian E. Norris ◽  
Pat J. B. Edwards ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Active Component ◽  
Germ Tube ◽  
Nitrogen Sources ◽  
Hyphal Growth ◽  
Tube Formation ◽  
Size Exclusion ◽  
Yeast Cells ◽  
Induction Medium ◽  
Ph Optimum

Yeast cells of Candida albicans are induced by serum at 37 °C to produce germ tubes, the first step in a transition from yeast to hyphal growth. Previously, it has been shown that the active component is not serum albumin but is present in the dialysable fraction of serum. In this study, serum induction of germ-tube formation is shown to occur even in the presence of added exogenous nitrogen sources and is therefore not signalled by nitrogen derepression. The active component in serum was purified by ion-exchange, reverse-phase and size-exclusion chromatography from the dialysable fraction of serum and was identified by NMR to be d-glucose. Enzymic destruction of glucose, using glucose oxidase, demonstrated that d-glucose was the only active component in these fractions. Induction of germ-tube formation by d-glucose required a temperature of 37 °C and the pH optimum was between pH 7·0 and 8·0. d-Glucose induced germ-tube formation in a panel of clinical isolates of C. albicans. Although d-glucose is the major inducer in serum, a second non-dialysable, trichloroacetic acid precipitable inducer is also present. However, whereas either 1·4 % (v/v) serum or an equivalent concentration of d-glucose induced 50 % germ-tube formation, the non-dialysable component required a 10-fold higher concentration to induce 50 % germ-tube formation. Serum is, therefore, the most effective induction medium for germ-tube formation because it is buffered at about pH 8·5 and contains two distinct inducers (glucose and a non-dialysable component), both active at this pH.

scholarly journals A Candida albicans Temperature-Sensitivecdc12-6Mutant Identifies Roles for Septins in Selection of Sites of Germ Tube Formation and Hyphal Morphogenesis

2012 ◽  
Vol 11 (10) ◽  
pp. 1210-1218 ◽  
Author(s):  
Lifang Li ◽  
Chengda Zhang ◽  
James B. Konopka
Keyword(s):  
Candida Albicans ◽  
Germ Tube ◽  
Leading Edge ◽  
Hyphal Growth ◽  
Striking Difference ◽  
Temperature Sensitive ◽  
Content Type ◽  
Hyphal Morphogenesis ◽  
Germ Tubes ◽  
Selection Of

ABSTRACTSeptins were identified for their role in septation inSaccharomyces cerevisiaeand were subsequently implicated in other morphogenic processes. To study septins inCandida albicanshyphal morphogenesis, a temperature-sensitive mutation was created that altered the C terminus of the essential Cdc12 septin. Thecdc12-6cells grew well at room temperature, but at 37°C they displayed expected defects in septation, nuclear localization, and bud morphogenesis. Although serum stimulated thecdc12-6cells at 37°C to form germ tube outgrowths, the mutant could not maintain polarized hyphal growth and instead formed chains of elongated cell compartments. Serum also stimulated thecdc12-6mutant to induce a hyphal reporter gene (HWP1-GFP) and a characteristic zone of filipin staining at the leading edge of growth. Interestingly,cdc12-6cells shifted to 37°C in the absence of serum gradually displayed enriched filipin staining at the tip, which may be due to the altered cell cycle regulation. A striking difference from the wild type was that thecdc12-6cells frequently formed a second germ tube in close proximity to the first. The mutant cells also failed to form the diffuse band of septins at the base of germ tubes and hyphae, indicating that this septin band plays a role in preventing proximal formation of germ tubes in a manner analogous to bud site selection. These studies demonstrate that not only are septins important for cytokinesis, but they also promote polarized morphogenesis and selection of germ tube sites that may help disseminate an infection in host tissues.

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