scholarly journals Modulation of the complex regulatory network for methionine biosynthesis in fungi

Genetics ◽  
2021 ◽  
Vol 217 (2) ◽  
Author(s):  
Manjari Shrivastava ◽  
Jinrong Feng ◽  
Mark Coles ◽  
Benjamin Clark ◽  
Amjad Islam ◽  
...  
Keyword(s):  
Filamentous Fungi ◽  
Fungal Pathogen ◽  
Biosynthetic Pathway ◽  
Protein A ◽  
Central Metabolism ◽  
Methionine Biosynthesis ◽  
Central Elements ◽  
Sulfur Containing ◽  
Complex Regulatory Network ◽  
Inorganic Sulfate

Abstract The assimilation of inorganic sulfate and the synthesis of the sulfur-containing amino acids methionine and cysteine is mediated by a multibranched biosynthetic pathway. We have investigated this circuitry in the fungal pathogen Candida albicans, which is phylogenetically intermediate between the filamentous fungi and Saccharomyces cerevisiae. In S. cerevisiae, this pathway is regulated by a collection of five transcription factors (Met4, Cbf1, Met28, and Met31/Met32), while in the filamentous fungi the pathway is controlled by a single Met4-like factor. We found that in C. albicans, the Met4 ortholog is also a core regulator of methionine biosynthesis, where it functions together with Cbf1. While C. albicans encodes this Met4 protein, a Met4 paralog designated Met28 (Orf19.7046), and a Met31 protein, deletion, and activation constructs suggest that of these proteins only Met4 is actually involved in the regulation of methionine biosynthesis. Both Met28 and Met31 are linked to other functions; Met28 appears essential, and Met32 appears implicated in the regulation of genes of central metabolism. Therefore, while S. cerevisiae and C. albicans share Cbf1 and Met4 as central elements of the methionine biosynthesis control, the other proteins that make up the circuit in S. cerevisiae are not members of the C. albicans control network, and so the S. cerevisiae circuit likely represents a recently evolved arrangement.

scholarly journals Cystathionine β-Lyase Is Important for Virulence of Salmonella enterica Serovar Typhimurium

2004 ◽  
Vol 72 (6) ◽  
pp. 3310-3314 ◽  
Author(s):  
Linda J. Ejim ◽  
Vanessa M. D'Costa ◽  
Nadine H. Elowe ◽  
J. Concepción Loredo-Osti ◽  
Danielle Malo ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Biosynthetic Pathway ◽  
Antibacterial Agents ◽  
Antimicrobial Agents ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Systemic Infection ◽  
Bacterial Virulence ◽  
Methionine Biosynthesis ◽  
Insertional Inactivation ◽  
Serovar Typhimurium

ABSTRACT The biosynthesis of methionine in bacteria requires the mobilization of sulfur from Cys by the formation and degradation of cystathionine. Cystathionine β-lyase, encoded by metC in bacteria and STR3 in Schizosaccharomyces pombe, catalyzes the breakdown of cystathionine to homocysteine, the penultimate step in methionine biosynthesis. This enzyme has been suggested to be the target for pyridinamine antimicrobial agents. We have demonstrated, by using purified enzymes from bacteria and yeast, that cystathionine β-lyase is not the likely target of these agents. Nonetheless, an insertional inactivation of metC in Salmonella enterica serovar Typhimurium resulted in the attenuation of virulence in a mouse model of systemic infection. This result confirms a previous chemical validation of the Met biosynthetic pathway as a target for the development of antibacterial agents and demonstrates that cystathionine β-lyase is important for bacterial virulence.

Sulfation by human lung fibroblasts: SO4(2-) and sulfur-containing amino acids as sources for macromolecular sulfation

1991 ◽  
Vol 260 (6) ◽  
pp. L450-L456 ◽  
Author(s):  
A. Elgavish ◽  
E. Meezan
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Human Lung ◽  
Lung Fibroblasts ◽  
Human Lung Fibroblasts ◽  
Physiological Conditions ◽  
Limiting Step ◽  
Sulfate Incorporation ◽  
Sulfur Containing ◽  
Inorganic Sulfate

Studies were carried out in human lung fibroblasts (IMR-90) to investigate 1) the relative contribution of two extracellular pools, inorganic sulfate and sulfur-containing amino acids, to the intracellular fraction precipitable by trichloroacetic acid and 2) the possibility that the transport of these sulfur-containing substrates at the plasma membrane may be a limiting step for macromolecular sulfation. Our studies indicate that the ability to use SO4(2-) released by intracellular catabolism of the sulfur-containing amino acid L-cysteine differs from one cell system to another. In contrast to smooth muscle cells, in the human lung fibroblast, L-cysteine contributes significantly to the intercellular pool of SO4(2-) used for sulfation at extracellular [SO4(2-)] less than 100 microM. However, under physiological conditions with respect to SO4(2-) ([SO4(2-)]0 = 300 microM), L-cysteine does not contribute greater than 30% of the sulfate incorporated into the cellular fraction. Taurine (2-aminoethanesulfonic acid) inhibits SO4(2-) incorporation into the cell-associated macromolecular fraction. However, results suggest that the effect is not due to either SO4(2-) released by its catabolism or to an effect on SO4(2-) transport into the cell. The fact that the transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibits sulfate incorporation indicates that carrier-mediated sulfate transport at the cellular plasma membrane may be a limiting step for sulfate incorporation. In conclusion, under physiological conditions with respect to SO4(2-), inorganic sulfate is a major source of sulfate for sulfation in human lung fibroblasts and macromolecular sulfation may be limited by its transport into the cells.

Rewiring of the Austinoid Biosynthetic Pathway in Filamentous Fungi

2017 ◽  
Vol 12 (12) ◽  
pp. 2927-2933 ◽  
Author(s):  
Derek J. Mattern ◽  
Vito Valiante ◽  
Fabian Horn ◽  
Lutz Petzke ◽  
Axel A. Brakhage
Keyword(s):  
Filamentous Fungi ◽  
Biosynthetic Pathway

scholarly journals Pathway for the Biosynthesis of the Pigment Chrysogine by Penicillium chrysogenum

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Annarita Viggiano ◽  
Oleksandr Salo ◽  
Hazrat Ali ◽  
Wiktor Szymanski ◽  
Peter P. Lankhorst ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Filamentous Fungi ◽  
Penicillium Chrysogenum ◽  
Biosynthetic Pathway ◽  
Biosynthetic Gene Cluster ◽  
Culture Broth ◽  
Yellow Pigment ◽  
Metabolic Potential ◽  
Content Type ◽  
Related Compounds

ABSTRACT Chrysogine is a yellow pigment produced by Penicillium chrysogenum and other filamentous fungi. Although the pigment was first isolated in 1973, its biosynthetic pathway has so far not been resolved. Here, we show that deletion of the highly expressed nonribosomal peptide synthetase (NRPS) gene Pc21g12630 ( chyA ) resulted in a decrease in the production of chrysogine and 13 related compounds in the culture broth of P. chrysogenum . Each of the genes of the chyA -containing gene cluster was individually deleted, and corresponding mutants were examined by metabolic profiling in order to elucidate their function. The data suggest that the NRPS ChyA mediates the condensation of anthranilic acid and alanine into the intermediate 2-(2-aminopropanamido)benzoic acid, which was verified by feeding experiments of a ΔchyA strain with the chemically synthesized product. The remainder of the pathway is highly branched, yielding at least 13 chrysogine-related compounds. IMPORTANCE Penicillium chrysogenum is used in industry for the production of β-lactams, but also produces several other secondary metabolites. The yellow pigment chrysogine is one of the most abundant metabolites in the culture broth, next to β-lactams. Here, we have characterized the biosynthetic gene cluster involved in chrysogine production and elucidated a complex and highly branched biosynthetic pathway, assigning each of the chrysogine cluster genes to biosynthetic steps and metabolic intermediates. The work further unlocks the metabolic potential of filamentous fungi and the complexity of secondary metabolite pathways.

scholarly journals Specificity in glycosylation of multiple flagellins by the modular and cell cycle regulated glycosyltransferase FlmG

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Silvia Ardissone ◽  
Nicolas Kint ◽  
Patrick H Viollier
Keyword(s):  
Cell Cycle ◽  
Substrate Specificity ◽  
Biosynthetic Pathway ◽  
Caulobacter Crescentus ◽  
Protein A ◽  
Post Translational Modification ◽  
New Class ◽  
Pseudaminic Acid ◽  
Secretion Chaperone ◽  
Glycosylation Pathway

How specificity is programmed into post-translational modification of proteins by glycosylation is poorly understood, especially for O-linked glycosylation systems. Here we reconstitute and dissect the substrate specificity underpinning the cytoplasmic O-glycosylation pathway that modifies all six flagellins, five structural and one regulatory paralog, in Caulobacter crescentus, a monopolarly flagellated alpha-proteobacterium. We characterize the biosynthetic pathway for the sialic acid-like sugar pseudaminic acid and show its requirement for flagellation, flagellin modification and efficient export. The cognate NeuB enzyme that condenses phosphoenolpyruvate with a hexose into pseudaminic acid is functionally interchangeable with other pseudaminic acid synthases. The previously unknown and cell cycle-regulated FlmG protein, a defining member of a new class of cytoplasmic O-glycosyltransferases, is required and sufficient for flagellin modification. The substrate specificity of FlmG is conferred by its N-terminal flagellin-binding domain. FlmG accumulates before the FlaF secretion chaperone, potentially timing flagellin modification, export, and assembly during the cell division cycle.

scholarly journals Recent advances in understanding Candida albicans hyphal growth

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 700 ◽  
Author(s):  
Robert A. Arkowitz ◽  
Martine Bassilana
Keyword(s):  
Candida Albicans ◽  
Medical Research ◽  
Filamentous Fungi ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Morphological Changes ◽  
Hyphal Growth ◽  
Yeast Form ◽  
Intensive Research ◽  
Human Fungal Pathogen

Morphological changes are critical for the virulence of a range of plant and human fungal pathogens. Candida albicans is a major human fungal pathogen whose ability to switch between different morphological states is associated with its adaptability and pathogenicity. In particular, C. albicans can switch from an oval yeast form to a filamentous hyphal form, which is characteristic of filamentous fungi. What mechanisms underlie hyphal growth and how are they affected by environmental stimuli from the host or resident microbiota? These questions are the focus of intensive research, as understanding C. albicans hyphal growth has broad implications for cell biological and medical research.

scholarly journals Phagocytic predation by the fungivorous amoeba Protostelium aurantium targets metal ion and redox homeostasis

2019 ◽  
Author(s):  
Silvia Radosa ◽  
Jakob L. Sprague ◽  
Renáta Tóth ◽  
Thomas Wolf ◽  
Marcel Sprenger ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Metal Ion ◽  
Redox Homeostasis ◽  
Intracellular Killing ◽  
Methionine Biosynthesis ◽  
Basic Tool ◽  
Transcriptional Responses ◽  
Gene Deletions ◽  
The Third ◽  
Phagocytic Killing

SummaryPredatory interactions among microbes are considered to be a major evolutionary driving force for biodiversity and the defense against phagocytic killing. The fungivorous amoeba Protostelium aurantium has a wide fungal food spectrum but strongly discriminates among major pathogenic members of the Saccharomycotina. While C. albicans is not recognized, C. glabrata is rapidly internalized, but remains undigested. Phagocytic killing and feeding by P. aurantium is highly effective for the third major fungal pathogen, C. parapsilosis. Here we show that the different prey patterns of the three yeasts were reflected by distinct transcriptional responses, indicating fungal copper and redox homeostasis as primary targets during intracellular killing of C. parapsilosis. Gene deletions in this fungus for the highly expressed copper exporter Crp1 and the peroxiredoxin Prx1 confirmed their role in copper and redox homeostasis, respectively and identified methionine biosynthesis as a ROS sensitive metabolic target during predation. Both, intact Cu export and redox homeostasis contributed to the survival of C. parapsilosis not only when encountering P. aurantium, but also in the presence of human macrophages. As both genes were found to be widely conserved within the entire Candida clade, our results suggest that they could be part of a basic tool-kit to survive phagocytic attacks by environmental predators.

scholarly journals Transcriptional Profiling of XdrA, a New Regulator of spa Transcription in Staphylococcus aureus

2010 ◽  
Vol 192 (19) ◽  
pp. 5151-5164 ◽  
Author(s):  
N. McCallum ◽  
J. Hinds ◽  
M. Ender ◽  
B. Berger-Bächi ◽  
P. Stutzmann Meier
Keyword(s):  
Staphylococcus Aureus ◽  
Reporter Gene ◽  
Transcriptional Profiling ◽  
Protein A ◽  
Dna Binding Protein ◽  
Infection Process ◽  
Gene Fusions ◽  
Temporal Expression ◽  
Nested Deletions ◽  
Complex Regulatory Network

ABSTRACT Transcription of spa, encoding the virulence factor protein A in Staphylococcus aureus, is tightly controlled by a complex regulatory network, ensuring its temporal expression over growth and at appropriate stages of the infection process. Transcriptomic profiling of XdrA, a DNA-binding protein that is conserved in all S. aureus genomes and shares similarity with the XRE family of helix-turn-helix, antitoxin-like proteins, revealed it to be a previously unidentified activator of spa transcription. To assess how XdrA fits into the complex web of spa regulation, a series of regulatory mutants were constructed; consisting of single, double, triple, and quadruple mutants lacking XdrA and/or the three key regulators previously shown to influence spa transcription directly (SarS, SarA, and RNAIII). A series of lacZ reporter gene fusions containing nested deletions of the spa promoter identified regions influenced by XdrA and the other three regulators. XdrA had almost as strong an activating effect on spa as SarS and acted on the same spa operator regions as SarS, or closely overlapping regions. All data from microarrays, Northern and Western blot analyses, and reporter gene fusion experiments indicated that XdrA is a major activator of spa expression that appears to act directly on the spa promoter and not through previously characterized regulators.

scholarly journals VITAMIN A AND ENDOCHONDRAL OSSIFICATION IN THE RAT AS INDICATED BY THE USE OF SULFUR-35 AND PHOSPHORUS-32

1954 ◽  
Vol 100 (1) ◽  
pp. 11-24 ◽  
Author(s):  
Dominic D. Dziewiatkowski
Keyword(s):  
Vitamin A ◽  
Chondroitin Sulfate ◽  
Endochondral Ossification ◽  
Specific Activity ◽  
Epiphyseal Cartilage ◽  
Sulfate Sulfur ◽  
A Value ◽  
Sulfur Containing ◽  
Inorganic Sulfate

The administration of vitamin A to vitamin A-deficient rats resulted in a decreased concentration of inorganic sulfate-sulfur in the serum from a value of 2.5 mg. per cent to 1.8 mg. per cent, the latter being close to the value of 2.0 mg. per cent found in normal rats of the same age. The uptake of sulfate and phosphate by femurs and tibiae of vitamin A-deficient rats was less than that in normal rats of the same age. An increased uptake followed the administration of vitamin A: radioautography indicated that in the case of sulfate, its uptake was particularly increased in the epiphyseal cartilage; an increased uptake of phosphate was particularly evident in the diaphysis immediately adjacent to the epiphyseal cartilage plate. The specific activity of the sulfate-sulfur in the chondroitin sulfate samples isolated from the skeletons of vitamin A-deficient rats fell progressively as the deficiency continued. Following administration of vitamin A, the specific activity approached and exceeded the value given by the sample from the skeletons of normal rats of the same age. A substantial increase was found in the value of the specific activity of the sulfate-sulfur of sulfomucopolysaccharides isolated from skins of vitamin A-deficient rats that had been given vitamin A. Following administration of vitamin A to rats deficient in this vitamin, an increased accumulation of some sulfur-containing material was found in regions of active calcification.

scholarly journals Reconfiguration of Transcriptional Control of Lysine Biosynthesis in Candida albicans Involves a Central Role for the Gcn4 Transcriptional Activator

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Yumnam Priyadarshini ◽  
Krishnamurthy Natarajan
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Fungal Pathogen ◽  
Biosynthetic Pathway ◽  
Transcriptional Regulator ◽  
Lysine Biosynthesis ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Starvation Conditions

ABSTRACT Microbes evolve rapidly so as to reconfigure their gene expression to adapt to the metabolic demands in diverse environmental niches. Here, we explored how conditions of nutrient deprivation regulate lysine biosynthesis in the human fungal pathogen Candida albicans. We show that although both Saccharomyces cerevisiae and C. albicans respond to lysine deprivation by transcriptional upregulation of lysine biosynthesis, the regulatory factors required for this control have been reconfigured in these species. We found that Gcn4 is an essential and direct transcriptional regulator of the expression of lysine biosynthetic genes under lysine starvation conditions in C. albicans. Our results therefore suggest that the regulation of the lysine biosynthetic pathway in Candida clade genomes involves gain of function by the master transcriptional regulator Gcn4, coincident with the neofunctionalization of the S. cerevisiae pathway-specific regulator Lys14. Evolution of transcriptional control is essential for organisms to cope with diversification into a spectrum of environments, including environments with limited nutrients. Lysine biosynthesis in fungi occurs in eight enzymatic steps. In Saccharomyces cerevisiae, amino acid starvation elicits the induction of LYS gene expression, mediated by the master regulator Gcn4 and the pathway-specific transcriptional regulator Lys14. Here, we have shown that the activation of LYS gene expression in the human fungal pathogen Candida albicans is predominantly controlled by Gcn4 under amino acid starvation conditions. Multiple lines of study showed that the four C. albicans LYS14-like genes have no role in the regulation of lysine biosynthesis. Whereas Gcn4 is dispensable for the growth of S. cerevisiae under lysine deprivation conditions, it is an essential regulator required for the growth of C. albicans under these conditions, as gcn4 deletion caused lysine auxotrophy. Gcn4 is required for the induction of increased LYS2 and LYS9 mRNA but not for the induction of increased LYS4 mRNA. Under lysine or isoleucine-valine deprivation conditions, Gcn4 recruitment to LYS2 and LYS9 promoters was induced in C. albicans. Indeed, in contrast to the S. cerevisiae LYS gene promoters, all LYS gene promoters in C. albicans harbored a Gcn4 binding site but not all harbored the S. cerevisiae Lys14 binding site, indicating the evolutionary divergence of cis-regulatory motifs. Thus, the transcriptional rewiring of the lysine biosynthetic pathway in C. albicans involves not only neofunctionalization of the four LYS14-like genes but the attendant strengthening of control by Gcn4, indicating a coordinated response with a much broader scope for control of amino acid biosynthesis in this human pathogen. IMPORTANCE Microbes evolve rapidly so as to reconfigure their gene expression to adapt to the metabolic demands in diverse environmental niches. Here, we explored how conditions of nutrient deprivation regulate lysine biosynthesis in the human fungal pathogen Candida albicans. We show that although both Saccharomyces cerevisiae and C. albicans respond to lysine deprivation by transcriptional upregulation of lysine biosynthesis, the regulatory factors required for this control have been reconfigured in these species. We found that Gcn4 is an essential and direct transcriptional regulator of the expression of lysine biosynthetic genes under lysine starvation conditions in C. albicans. Our results therefore suggest that the regulation of the lysine biosynthetic pathway in Candida clade genomes involves gain of function by the master transcriptional regulator Gcn4, coincident with the neofunctionalization of the S. cerevisiae pathway-specific regulator Lys14.

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