scholarly journals Mediator Tail Module Is Required for Tac1-Activated CDR1 Expression and Azole Resistance in Candida albicans

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Zhongle Liu ◽  
Lawrence C. Myers
Keyword(s):  
Candida Albicans ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Full Length ◽  
Common Mechanism ◽  
Azole Resistance ◽  
Content Type ◽  
Transcriptional Activation Domain ◽  
C Terminus ◽  
Absolute Potential

ABSTRACT The human fungal pathogen Candida albicans develops drug resistance after long-term exposure to azole drugs in the treatment of chronic candidiasis. Gain-of-function (GOF) mutations in the transcription factor Tac1 and the consequent expression of its targets, drug efflux pumps Cdr1 and Cdr2, are a common mechanism by which C. albicans acquires fluconazole resistance. The mechanism by which GOF mutations hyperactivate Tac1 is currently unknown. Here, we define a transcriptional activation domain (TAD) at the C terminus of Tac1. GOF mutations within the Tac1 TAD, outside the context of full-length Tac1, generally do not enhance its absolute potential as a transcriptional activator. Negative regulation of the Tac1 TAD by the Tac1 middle region is necessary for the activating effect of GOF mutations or fluphenazine to be realized. We have found that full-length Tac1, when hyperactivated by xenobiotics or GOF mutations, facilitates the recruitment of the Mediator coactivator complex to the CDR1 promoter. Azole resistance and the activation of Tac1 target genes, such as CDR1, are dependent on the Tac1 TAD and subunits of the Mediator tail module. The dependence of different Tac1 target promoters on the Mediator tail module, however, varies widely. Lastly, we show that hyperactivation of Tac1 is correlated with its Mediator-dependent phosphorylation, a potentially useful biomarker for Tac1 hyperactivation. The role of Mediator in events downstream of Tac1 hyperactivation in fluconazole-resistant clinical isolates is complex and provides opportunities and challenges for therapeutic intervention.

scholarly journals Identification of the Candida albicans Cap1p Regulon

2009 ◽  
Vol 8 (6) ◽  
pp. 806-820 ◽  
Author(s):  
Sadri Znaidi ◽  
Katherine S. Barker ◽  
Sandra Weber ◽  
Anne-Marie Alarco ◽  
Teresa T. Liu ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Target Genes ◽  
Open Reading Frames ◽  
Nuclear Retention ◽  
Tiling Microarrays ◽  
Rich Domain ◽  
C Terminus

ABSTRACT Cap1p, a transcription factor of the basic region leucine zipper family, regulates the oxidative stress response (OSR) in Candida albicans. Alteration of its C-terminal cysteine-rich domain (CRD) results in Cap1p nuclear retention and transcriptional activation. To better understand the function of Cap1p in C. albicans, we used genome-wide location profiling (chromatin immunoprecipitation-on-chip) to identify its transcriptional targets in vivo. A triple-hemagglutinin (HA3) epitope was introduced at the C terminus of wild-type Cap1p (Cap1p-HA3) or hyperactive Cap1p with an altered CRD (Cap1p-CSE-HA3). Location profiling using whole-genome oligonucleotide tiling microarrays identified 89 targets bound by Cap1p-HA3 or Cap1p-CSE-HA3 (the binding ratio was at least twofold; P ≤ 0.01). Strikingly, Cap1p binding was detected not only at the promoter region of its target genes but also at their 3′ ends and within their open reading frames, suggesting that Cap1p may associate with the transcriptional or chromatin remodeling machinery to exert its activity. Overrepresented functional groups of the Cap1p targets (P ≤ 0.02) included 11 genes involved in the OSR (CAP1, GLR1, TRX1, SOD1, CAT1, and others), 13 genes involved in response to drugs (PDR16, MDR1, FLU1, YCF1, FCR1, and others), 4 genes involved in phospholipid transport (PDR16, GIT1, RTA2, and orf19.932), and 3 genes involved in the regulation of nitrogen utilization (GST3, orf19.2693, and orf19.3121), suggesting that Cap1p has other cellular functions in addition to the OSR. Bioinformatic analyses of the bound sequences suggest that Cap1p recognizes the DNA motif 5′-MTKASTMA. Finally, transcriptome analyses showed that increased expression generally accompanies Cap1p binding at its targets, indicating that Cap1p functions as a transcriptional activator.

scholarly journals Distinct Mechanism for the Formation of the Ribonucleoprotein Complex of Tomato Spotted Wilt Virus

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Yu Guo ◽  
Baocheng Liu ◽  
Zhenzhen Ding ◽  
Guobang Li ◽  
Meizi Liu ◽  
...  
Keyword(s):  
Tomato Spotted Wilt Virus ◽  
Higher Order ◽  
The Body ◽  
Full Length ◽  
Content Type ◽  
Ribonucleoprotein Complex ◽  
Tomato Spotted Wilt ◽  
Distinct Mechanism ◽  
C Terminus ◽  
Wilt Virus

ABSTRACT The Tomato spotted wilt virus (TSWV) belongs to the Tospovirus genus of the Bunyaviridae family and represents the sole plant-infecting group within bunyavirus. TSWV encodes a nucleocapsid protein (N) which encapsidates the RNA genome to form a ribonucleoprotein complex (RNP). In addition, the N has multiple roles during the infection of plant cells. Here, we report the crystal structure of the full-length TSWV N. The N features a body domain consisting of an N-lobe and a C-lobe. These lobes clamp a positively charged groove which may constitute the RNA binding site. Furthermore, the body domains are flanked by N- and C-terminal arms which mediate homotypic interactions to the neighboring subunits, resulting in a ring-shaped N trimer. Interestingly, the C terminus of one protomer forms an additional interaction with the protomer of an adjacent trimer in the crystal, which may constitute a higher-order oligomerization contact. In this way, this study provides insights into the structure and trimeric assembly of TSWV N, which help to explain previous functional findings, but also suggests distinct N interactions within a higher-order RNP. IMPORTANCE TSWV is one of the most devastating plant pathogens that cause severe diseases in numerous agronomic and ornamental crops worldwide. TSWV is also the prototypic member of the Tospovirus genus, which is the sole group of plant-infecting viruses in the bunyavirus family. This study determined the structure of full-length TSWV N in an oligomeric state. The structural observations explain previously identified biological properties of TSWV N. Most importantly, the additional homotypic interaction between the C terminus of one protomer with another protomer indicates that there is a distinct mechanism of RNP formation in the bunyavirus family, thereby enhancing the current knowledge of negative-sense single-stranded RNA virus-encoded N. TSWV N is the last remaining representative N with an unknown structure in the bunyavirus family. Combined with previous studies, the structure of TSWV N helps to build a complete picture of the bunyavirus-encoded N family and reveals a close evolutionary relationship between orthobunyavirus, phlebovirus, hantavirus, and tospovirus.

scholarly journals Direct activation of Sex-lethal transcription by the Drosophila runt protein

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 191-200 ◽  
Author(s):  
S.G. Kramer ◽  
T.M. Jinks ◽  
P. Schedl ◽  
J.P. Gergen
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
Specific Binding ◽  
Binding Activity ◽  
Transcriptional Activation Domain ◽  
Downstream Target ◽  
Early Promoter ◽  
Dna Binding Activity ◽  
Sex Lethal

Runt functions as a transcriptional regulator in multiple developmental pathways in Drosophila melanogaster. Recent evidence indicates that Runt represses the transcription of several downstream target genes in the segmentation pathway. Here we demonstrate that runt also functions to activate transcription. The initial expression of the female-specific sex-determining gene Sex-lethal in the blastoderm embryo requires runt activity. Consistent with a role as a direct activator, Runt shows sequence-specific binding to multiple sites in the Sex-lethal early promoter. Using an in vivo transient assay, we demonstrate that Runt's DNA-binding activity is essential for Sex-lethal activation in vivo. These experiments further reveal that increasing the dosage of runt alone is sufficient for triggering the transcriptional activation of Sex-lethal in males. In addition, a Runt fusion protein, containing a heterologous transcriptional activation domain activates Sex-lethal expression, indicating that this regulation is direct and not via repression of other repressors. Moreover, we demonstrate that a small segment of the Sex-lethal early promoter that contains Runt-binding sites mediates Runt-dependent transcriptional activation in vivo.

scholarly journals Functional Dissection of a Candida albicans Zinc Cluster Transcription Factor, the Multidrug Resistance Regulator Mrr1

2011 ◽  
Vol 10 (8) ◽  
pp. 1110-1121 ◽  
Author(s):  
Sabrina Schubert ◽  
Christina Popp ◽  
P. David Rogers ◽  
Joachim Morschhäuser
Keyword(s):  
Transcription Factor ◽  
Candida Albicans ◽  
Transcriptional Activation ◽  
Efflux Pump ◽  
Major Facilitator Superfamily ◽  
Constitutive Activity ◽  
Activation Domain ◽  
Pathogenic Yeast ◽  
Content Type ◽  
Zinc Cluster

ABSTRACTThe overexpression of theMDR1gene, which encodes a multidrug efflux pump of the major facilitator superfamily, is a frequent cause of resistance to the widely used antimycotic agent fluconazole and other toxic compounds in the pathogenic yeastCandida albicans. The zinc cluster transcription factor Mrr1 controlsMDR1expression in response to inducing chemicals, and gain-of-function mutations inMRR1are responsible for the constitutiveMDR1upregulation in fluconazole-resistantC. albicansstrains. To understand how Mrr1 activity is regulated, we identified functional domains of this transcription factor. A hybrid protein consisting of the N-terminal 106 amino acids of Mrr1 and the transcriptional activation domain of Gal4 fromSaccharomyces cerevisiaeconstitutively inducedMDR1expression, demonstrating that the DNA binding domain is sufficient to target Mrr1 to theMDR1promoter. Using a series of C-terminal truncations and systematic internal deletions, we could show that Mrr1 contains multiple activation and inhibitory domains. One activation domain (AD1) is located in the C terminus of Mrr1. When fused to the tetracycline repressor TetR, this distal activation domain induced gene expression from a TetR-dependent promoter. The deletion of an inhibitory region (ID1) located near the distal activation domain resulted in constitutive activity of Mrr1. The additional removal of AD1 abolished the constitutive activity, but the truncated Mrr1 still could activate theMDR1promoter in response to the inducer benomyl. These results demonstrate that the activity of Mrr1 is regulated in multiple ways and provide insights into the function of an important mediator of drug resistance inC. albicans.

scholarly journals Determination of the consensus DNA-binding sequence and a transcriptional activation domain for ESE-2

2006 ◽  
Vol 398 (3) ◽  
pp. 497-507 ◽  
Author(s):  
Yeon Sook Choi ◽  
Satrajit Sinha
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Regulatory Elements ◽  
Activation Domain ◽  
Transcriptional Activation Domain ◽  
Ets Proteins ◽  
Flanking Sequences ◽  
Binding Sequence

The ESE (epithelium-specific Ets) subfamily of Ets transcription factors plays an important role in regulating gene expression in a variety of epithelial cell types. Although ESE proteins have been shown to bind to regulatory elements of some epithelial genes, the optimal DNA-binding sequence has not been experimentally ascertained for any member of the ESE subfamily of transcription factors. This has made the identification and validation of their targets difficult. We are studying ESE-2 (Elf5), which is highly expressed in epithelial cells of many tissues including skin keratinocytes. Here, we identify the preferred DNA-binding site of ESE-2 by performing CASTing (cyclic amplification and selection of targets) experiments. Our analysis shows that the optimal ESE-2 consensus motif consists of a GGA core and an AT-rich 5′- and 3′-flanking sequences. Mutational and competition experiments demonstrate that the flanking sequences that confer high DNA-binding affinity for ESE-2 show considerable differences from the known consensus DNA-binding sites of other Ets proteins, thus reinforcing the idea that the flanking sequences may impart recognition specificity for Ets proteins. In addition, we have identified a novel isoform of murine ESE-2, ESE-2L, that is generated by use of a hitherto unreported new exon and an alternate promoter. Interestingly, transient transfection assays with an optimal ESE-2 responsive reporter show that both ESE-2 and ESE-2L are weak transactivators. However, similar studies utilizing GAL4 chimaeras of ESE-2 demonstrate that while the DNA-binding ETS (E twenty-six) domain functions as a repressor, the PNT (pointed domain) of ESE-2 can act as a potent transcriptional activation domain. This novel transactivating property of PNT is also shared by ESE-3, another ESE family member. Identification of the ESE-2 consensus site and characterization of the transcriptional activation properties of ESE-2 shed new light on its potential as a regulator of target genes.

scholarly journals Stress-induced binding of the transcriptional factor CHOP to a novel DNA control element.

1996 ◽  
Vol 16 (4) ◽  
pp. 1479-1489 ◽  
Author(s):  
M Ubeda ◽  
X Z Wang ◽  
H Zinszner ◽  
I Wu ◽  
J F Habener ◽  
...  
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Binding Activity ◽  
Control Element ◽  
Core Element ◽  
Transcriptional Activation Domain ◽  
Dna Binding Activity ◽  
Basic Region

CHOP (GADD153) is a mammalian nuclear protein that dimerizes with members of the C/EBP family of transcriptional factors. Absent under normal conditions, CHOP is induced by the stress encountered during nutrient deprivation, the acute-phase response, and treatment of cells with certain toxins. The basic region of CHOP deviates considerably in sequence from that of other C/EBP proteins, and CHOP-C/EBP heterodimers are incapable of binding to a common class of C/EBP sites. With respect to such sites, CHOP serves as an inhibitor of the activity of C/EBP proteins. However, recent studies indicate that certain functions of CHOP, such as the induction of growth arrest by overexpression of the wild-type protein and oncogenic transformation by the TLS-CHOP fusion protein, require an intact basic region, suggesting that DNA binding by CHOP may be implicated in these activities. In this study an in vitro PCR-based selection assay was used to identify sequences bound by CHOP-C/EBP dimers. These sequences were found to contain a unique core element PuPuPuTGCAAT(A/C)CCC. Competition in DNA-binding assays, DNase 1 footprint analysis, and methylation interference demonstrate that the binding is sequence specific. Deletions in the basic region of CHOP lead to a loss of DNA binding, suggesting that CHOP participates in this process. Stress induction in NIH 3T3 cells leads to the appearance of CHOP-containing DNA-binding activity. CHOP is found to contain a transcriptional activation domain which is inducible by cellular stress, lending further support to the notion that the protein can function as a positively acting transcription factor. We conclude that CHOP may serve a dual role both as an inhibitor of the ability of C/EBP proteins to activate some target genes and as a direct activator of others.

scholarly journals Rhb1 Regulates the Expression of Secreted Aspartic Protease 2 through the TOR Signaling Pathway in Candida albicans

2011 ◽  
Vol 11 (2) ◽  
pp. 168-182 ◽  
Author(s):  
Yu-Ting Chen ◽  
Chia-Ying Lin ◽  
Pei-Wen Tsai ◽  
Cheng-Yao Yang ◽  
Wen-Ping Hsieh ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Signaling Pathway ◽  
Virulence Factor ◽  
Nitrogen Availability ◽  
Target Genes ◽  
Small Gtpase ◽  
Aspartic Protease ◽  
Tor Signaling ◽  
Content Type

ABSTRACTCandida albicansis a major fungal pathogen in humans. InC. albicans, secreted aspartyl protease 2 (Sap2) is the most highly expressed secreted aspartic proteasein vitroand is a virulence factor. Recent research links the small GTPase Rhb1 toC. albicanstarget of rapamycin (TOR) signaling in response to nitrogen availability. The results of this study show that Rhb1 is related to cell growth through the control ofSAP2expression when protein is the major nitrogen source. This process involves various components of the TOR signaling pathway, including Tor1 kinase and its downstream effectors. TOR signaling not only controlsSAP2transcription but also affects Sap2 protein levels, possibly through general amino acid control. DNA microarray analysis identifies other target genes downstream of Rhb1 in addition toSAP2. These findings provide new insight into nutrients, Rhb1-TOR signaling, and expression ofC. albicansvirulence factor.

scholarly journals Fungemia Surveillance in Denmark Demonstrates Emergence of Non-albicans Candida Species and Higher Antifungal Usage and Resistance Rates than in Other Nations

2018 ◽  
Vol 56 (4) ◽  
pp. e01907-17 ◽  
Author(s):  
Mariana Castanheira
Keyword(s):  
Candida Albicans ◽  
Candida Species ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Fungal Species ◽  
Azole Resistance ◽  
Content Type ◽  
Fungal Organisms ◽  
Echinocandin Resistance ◽  
Resistance Rates

ABSTRACT Recent changes in the occurrence of fungal species and the difficulties in performing reference antifungal susceptibility testing highlight the importance of surveillance of fungal organisms and antifungal resistance rates. K. M. T. Astvad et al. report results from recent (2012 to 2015) fungemia surveillance in Denmark and compare the results to previous data (2004 to 2011), showing a decrease in Candida albicans infections accompanied by an increase in C. glabrata and C. dubliniensis infections (J Clin Microbiol 56:e01564-17, 2018, https://doi.org/10.1128/JCM.01564-17). Azole resistance among C. tropicalis and C. parapsilosis isolates and echinocandin resistance in C. krusei isolates were higher in Denmark than in other regions. Interestingly, the usage of antifungals is higher in Denmark than in other Nordic countries.

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