scholarly journals Inhibition of Dephosphorylation of Dolichyl Diphosphate Alters the Synthesis of Dolichol and Hinders Protein N-Glycosylation and Morphological Transitions in Candida albicans

2019 ◽  
Vol 20 (20) ◽  
pp. 5067 ◽  
Author(s):  
Anna Janik ◽  
Monika Niewiadomska ◽  
Urszula Perlińska-Lenart ◽  
Jacek Lenart ◽  
Damian Kołakowski ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Biofilm Formation ◽  
De Novo ◽  
Mevalonate Pathway ◽  
Yeast Species ◽  
Protein Glycosylation ◽  
De Novo Synthesis ◽  
Dolichyl Phosphate ◽  
Morphological Transitions

The essential role of dolichyl phosphate (DolP) as a carbohydrate carrier during protein N-glycosylation is well established. The cellular pool of DolP is derived from de novo synthesis in the dolichol branch of the mevalonate pathway and from recycling of DolPP after each cycle of N-glycosylation, when the oligosaccharide is transferred from the lipid carrier to the protein and DolPP is released and then dephosphorylated. In Saccharomyces cerevisiae, the dephosphorylation of DolPP is known to be catalyzed by the Cwh8p protein. To establish the role of the Cwh8p orthologue in another distantly related yeast species, Candida albicans, we studied its mutant devoid of the CaCWH8 gene. A double Cacwh8∆/Cacwh8∆ strain was constructed by the URA-blaster method. As in S. cerevisiae, the mutant was impaired in DolPP recycling. This defect, however, was accompanied by an elevation of cis-prenyltransferase activity and higher de novo production of dolichols. Despite these compensatory changes, protein glycosylation, cell wall integrity, filamentous growth, and biofilm formation were impaired in the mutant. These results suggest that the defects are not due to the lack of DolP for the protein N-glycosylation but rather that the activity of oligosacharyltransferase could be inhibited by the excess DolPP accumulating in the mutant.

scholarly journals Transposon Insertion in the purL Gene Induces Biofilm Depletion in Escherichia coli ATCC 25922

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 774
Author(s):  
Virginio Cepas ◽  
Victoria Ballén ◽  
Yaiza Gabasa ◽  
Miriam Ramírez ◽  
Yuly López ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
De Novo ◽  
Wild Type ◽  
Planktonic Cells ◽  
E Coli ◽  
Qrt Pcr ◽  
Transposon Insertion ◽  
De Novo Purine Biosynthesis

Current Escherichia coli antibiofilm treatments comprise a combination of antibiotics commonly used against planktonic cells, leading to treatment failure. A better understanding of the genes involved in biofilm formation could facilitate the development of efficient and specific new antibiofilm treatments. A total of 2578 E. coli mutants were generated by transposon insertion, of which 536 were analysed in this study. After sequencing, Tn263 mutant, classified as low biofilm-former (LF) compared to the wild-type (wt) strain (ATCC 25922), showed an interruption in the purL gene, involved in the de novo purine biosynthesis pathway. To elucidate the role of purL in biofilm formation, a knockout was generated showing reduced production of curli fibres, leading to an impaired biofilm formation. These conditions were restored by complementation of the strain or addition of exogenous inosine. Proteomic and transcriptional analyses were performed to characterise the differences caused by purL alterations. Thirteen proteins were altered compared to wt. The corresponding genes were analysed by qRT-PCR not only in the Tn263 and wt, but also in clinical strains with different biofilm activity. Overall, this study suggests that purL is essential for biofilm formation in E. coli and can be considered as a potential antibiofilm target.

scholarly journals The Role of Mitochondrial Dysfunction in the Progression of Alzheimer’s Disease

2019 ◽  
Vol 25 (40) ◽  
pp. 5578-5587 ◽  
Author(s):  
Claus Desler ◽  
Meryl S. Lillenes ◽  
Tone Tønjum ◽  
Lene Juel Rasmussen
Keyword(s):  
Alzheimer’S Disease ◽  
Reactive Oxygen Species ◽  
Alzheimer's Disease ◽  
Mitochondrial Dysfunction ◽  
De Novo ◽  
Oxygen Species ◽  
De Novo Synthesis ◽  
Atp Production ◽  
Essential Phospholipids

The current molecular understanding of Alzheimer’s disease (AD) has still not resulted in successful interventions. Mitochondrial dysfunction of the AD brain is currently emerging as a hallmark of this disease. One mitochondrial function often affected in AD is oxidative phosphorylation responsible for ATP production, but also for production of reactive oxygen species (ROS) and for the de novo synthesis of pyrimidines. This paper reviews the role of mitochondrial produced ROS and pyrimidines in the aetiology of AD and their proposed role in oxidative degeneration of macromolecules, synthesis of essential phospholipids and maintenance of mitochondrial viability in the AD brain.

scholarly journals Simple Carbohydrate Derivatives Diminish the Formation of Biofilm of the Pathogenic Yeast Candida albicans

Antibiotics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 10 ◽  
Author(s):  
Olena P. Ishchuk ◽  
Olov Sterner ◽  
Ulf Ellervik ◽  
Sophie Manner
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogen ◽  
Biofilm Formation ◽  
Untreated Control ◽  
Morphological Transition ◽  
Pathogenic Yeast ◽  
Yeast Form ◽  
Human Fungal Pathogen ◽  
Morphological Transitions ◽  
Simple Carbohydrate

The opportunistic human fungal pathogen Candida albicans relies on cell morphological transitions to develop biofilm and invade the host. In the current study, we developed new regulatory molecules, which inhibit the morphological transition of C. albicans from yeast-form cells to cells forming hyphae. These compounds, benzyl α-l-fucopyranoside and benzyl β-d-xylopyranoside, inhibit the hyphae formation and adhesion of C. albicans to a polystyrene surface, resulting in a reduced biofilm formation. The addition of cAMP to cells treated with α-l-fucopyranoside restored the yeast-hyphae switch and the biofilm level to that of the untreated control. In the β-d-xylopyranoside treated cells, the biofilm level was only partially restored by the addition of cAMP, and these cells remained mainly as yeast-form cells.

The role of particulate carbon in the de-novo synthesis of polychlorinated dibenzodioxins and-furans in fly-ash

Chemosphere ◽  
1990 ◽  
Vol 20 (10-12) ◽  
pp. 1953-1958 ◽  
Author(s):  
L. Stieglitz ◽  
G. Zwick ◽  
J. Beck ◽  
H. Bautz ◽  
W. Roth
Keyword(s):  
Fly Ash ◽  
De Novo ◽  
De Novo Synthesis ◽  
Particulate Carbon ◽  
Polychlorinated Dibenzodioxins

scholarly journals NAD+-Dependent Deacetylase Hst1p Controls Biosynthesis and Cellular NAD+ Levels in Saccharomyces cerevisiae

2003 ◽  
Vol 23 (19) ◽  
pp. 7044-7054 ◽  
Author(s):  
Antonio Bedalov ◽  
Maki Hirao ◽  
Jeffrey Posakony ◽  
Melisa Nelson ◽  
Julian A. Simon
Keyword(s):  
De Novo ◽  
Critical Role ◽  
Salvage Pathway ◽  
De Novo Synthesis ◽  
Array Analysis ◽  
Binding Partner ◽  
Dependent Protein ◽  
New Protein

ABSTRACT Nicotine adenine dinucleotide (NAD+) performs key roles in electron transport reactions, as a substrate for poly(ADP-ribose) polymerase and NAD+-dependent protein deacetylases. In the latter two processes, NAD+ is consumed and converted to ADP-ribose and nicotinamide. NAD+ levels can be maintained by regeneration of NAD+ from nicotinamide via a salvage pathway or by de novo synthesis of NAD+ from tryptophan. Both pathways are conserved from yeast to humans. We describe a critical role of the NAD+-dependent deacetylase Hst1p as a sensor of NAD+ levels and regulator of NAD+ biosynthesis. Using transcript arrays, we show that low NAD+ states specifically induce the de novo NAD+ biosynthesis genes while the genes in the salvage pathway remain unaffected. The NAD+-dependent deacetylase activity of Hst1p represses de novo NAD+ biosynthesis genes in the absence of new protein synthesis, suggesting a direct effect. The known Hst1p binding partner, Sum1p, is present at promoters of highly inducible NAD+ biosynthesis genes. The removal of HST1-mediated repression of the NAD+ de novo biosynthesis pathway leads to increased cellular NAD+ levels. Transcript array analysis shows that reduction in cellular NAD+ levels preferentially affects Hst1p-regulated genes in comparison to genes regulated with other NAD+-dependent deacetylases (Sir2p, Hst2p, Hst3p, and Hst4p). In vitro experiments demonstrate that Hst1p has relatively low affinity toward NAD+ in comparison to other NAD+-dependent enzymes. These findings suggest that Hst1p serves as a cellular NAD+ sensor that monitors and regulates cellular NAD+ levels.

scholarly journals SCAP/SREBP pathway is required for the full steroidogenic response to cyclic AMP

2016 ◽  
Vol 113 (38) ◽  
pp. E5685-E5693 ◽  
Author(s):  
Masami Shimizu-Albergine ◽  
Brian Van Yserloo ◽  
Martin G. Golkowski ◽  
Shao-En Ong ◽  
Joseph A. Beavo ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Leydig Cells ◽  
De Novo ◽  
Regulatory Element ◽  
De Novo Synthesis ◽  
Intracellular Lipid ◽  
Element Binding Protein ◽  
Short Palindromic Repeat ◽  
Sterol Regulatory Element

Luteinizing hormone (LH) stimulates steroidogenesis largely through a surge in cyclic AMP (cAMP). Steroidogenic rates are also critically dependent on the availability of cholesterol at mitochondrial sites of synthesis. This cholesterol is provided by cellular uptake of lipoproteins, mobilization of intracellular lipid, and de novo synthesis. Whether and how these pathways are coordinated by cAMP are poorly understood. Recent phosphoproteomic analyses of cAMP-dependent phosphorylation sites in MA10 Leydig cells suggested that cAMP regulates multiple steps in these processes, including activation of the SCAP/SREBP pathway. SCAP [sterol-regulatory element-binding protein (SREBP) cleavage-activating protein] acts as a cholesterol sensor responsible for regulating intracellular cholesterol balance. Its role in cAMP-mediated control of steroidogenesis has not been explored. We used two CRISPR (clustered regularly interspaced short palindromic repeat)-Cas9 (CRISPR associated protein 9) knockout approaches to test the role of SCAP in steroidogenesis. Our results demonstrate that SCAP is required for progesterone production induced by concurrent inhibition of the cAMP phosphodiesterases PDE4 and PDE8. These inhibitors increased SCAP phosphorylation, SREBP2 activation, and subsequent expression of cholesterol biosynthetic genes, whereas SCAP deficiency largely prevented these effects. Reexpression of SCAP in SCAP-deficient cells restored SREBP2 protein expression and partially restored steroidogenic responses, confirming the requirement of SCAP–SREBP2 in steroidogenesis. Inhibitors of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase and isoprenylation attenuated, whereas exogenously provided cholesterol augmented, PDE inhibitor-induced steroidogenesis, suggesting that the cholesterol substrate needed for steroidogenesis is provided by both de novo synthesis and isoprenylation-dependent mechanisms. Overall, these results demonstrate a novel role for LH/cAMP in SCAP/SREBP activation and subsequent regulation of steroidogenesis.

scholarly journals Role of SFP1 in the Regulation of Candida albicans Biofilm Formation

PLoS ONE ◽  
2015 ◽  
Vol 10 (6) ◽  
pp. e0129903 ◽  
Author(s):  
Hsueh-Fen Chen ◽  
Chung-Yu Lan
Keyword(s):  
Candida Albicans ◽  
Biofilm Formation

scholarly journals Investigating the Function of Ddr48p in Candida albicans

2012 ◽  
Vol 11 (6) ◽  
pp. 718-724 ◽  
Author(s):  
I. A. Cleary ◽  
N. B. MacGregor ◽  
S. P. Saville ◽  
D. P. Thomas
Keyword(s):  
Candida Albicans ◽  
Biofilm Formation ◽  
The United States ◽  
Pathogenic Potential ◽  
Content Type ◽  
General Stress Response ◽  
Damage Response ◽  
Sense And Respond ◽  
Immune Defects

ABSTRACTCandidiasis now represents the fourth most frequent nosocomial infection both in the United States and worldwide.Candida albicansis an increasingly common threat to human health as a consequence of AIDS, steroid therapy, organ and tissue transplantation, cancer therapy, broad-spectrum antibiotics, and other immune defects. The pathogenic potential ofC. albicansis intimately related to certain key processes, including biofilm formation and filamentation. Ddr48p is a damage response protein that is significantly upregulated during both biofilm formation and filamentation, but its actual function is unknown. Previous studies have indicated that this protein may be essential inC. albicansbut notSaccharomyces cerevisiae. Here we examined the function of Ddr48p and investigated the role of this protein in biofilm formation and filamentation. We demonstrated that this protein is not essential inC. albicansand appears to be dispensable for filamentation. However,DDR48is required for the flocculation response stimulated by 3-aminotriazole-induced amino acid starvation. Furthermore, we examined the response of this deletion strain to a wide variety of environmental stressors and antifungal compounds. We observed several mild sensitivity or resistance phenotypes and also found that Ddr48p contributes to the DNA damage response ofC. albicans. The results of this study reveal that the role of this highly expressed protein goes beyond a general stress response and impinges on a key facet of pathogenesis, namely, the ability to sense and respond to changes in the host environment.

Characterization of the AMP-binding protein gene family in Arabidopsis thaliana: will the real acyl-CoA synthetases please stand up?

2000 ◽  
Vol 28 (6) ◽  
pp. 955-957 ◽  
Author(s):  
J. Shockey ◽  
J. Schnurr ◽  
J. Browse
Keyword(s):  
Protein Gene ◽  
De Novo ◽  
Functional Characterization ◽  
De Novo Synthesis ◽  
Triacylglycerol Composition ◽  
Sequence Comparisons ◽  
Triacylglycerol Metabolism ◽  
Binding Protein Gene

One of the most prominent and important topics in modern agricultural biotechnology is the manipulation of oilseed triacylglycerol composition. Towards this goal, we have sought to identify and characterize acyl-CoA synthetases (ACSs), which play an important role in both de novo synthesis and modification of existing lipids. We have identified and cloned 20 different genes that bear strong sequence homology to known ACSs from other organisms. Through sequence comparisons and functional characterization, we have identified several members of this group that encode ACSs, while the other genes fall into the broader category of genes for AMP-binding proteins (AMPBPs). Distinguishing ACSs from AMPBPs will simplify our efforts to understand the role of ACS in triacylglycerol metabolism.

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