Inhibitor Of Amino Acid Biosynthesis Research Articles

Amino Acid Biosynthesis Inhibitors in Tuberculosis Drug Discovery.

According to the latest World Health Organization (WHO) report, an estimated 10.6 million people were diagnosed with tuberculosis (TB) in 2022, and 1.30 million died. A major concern is the emergence of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) strains, fueled by the length of anti-TB treatment and HIV comorbidity. Innovative anti-TB agents acting with new modes of action are the only solution to counteract the spread of resistant infections. To escape starvation and survive inside macrophages, Mtb has evolved to become independent of the host by synthesizing its own amino acids. Therefore, targeting amino acid biosynthesis could subvert the ability of the mycobacterium to evade the host immune system, providing innovative avenues for drug discovery. The aim of this review is to give an overview of the most recent progress in the discovery of amino acid biosynthesis inhibitors. Among the hits discovered over the past five years, tryptophan (Trp) inhibitors stand out as the most advanced and have significantly contributed to demonstrating the feasibility of this approach for future TB drug discovery. Future efforts should be directed at prioritizing the chemical optimization of these hits to enrich the TB drug pipeline with high-quality leads.

Potential role of nitrogen in spore dispersal and infection of Paraphysoderma sedebokerense, a fungal parasite of Haematococcus pluvialis

Paraphysoderma sedebokerense, a parasitic fungus in Blastocladiomycota, can infect the microalga Haematococcus pluvialis and cause culture crashes. The early development including encystment and cyst germination of P. sedebokerense on microalgal cell walls is vital to the parasitism process. To evaluate the potential role of nitrogen in the early development of P. sedebokerense, we analyzed colony formation of P. sedebokerense on agar plates containing inorganic nitrogen (i.e., nitrate), transcriptome of P. sedebokerense during encystment and penetration, amino acid utilization by P. sedebokerense and amino acid profile of microalgal cell walls. Results indicated that nitrate facilitated the dispersal of amoeboid swarmers from sporangia. Transcriptome analysis indicated that Gene Ontology (GO) terms related to nitrate assimilation and methionine biosynthesis were enriched in P. sedebokerense when it encysted and penetrated the microalgal cell walls. Furthermore, amoeboid swarmers can encyst and penetrate the extracellular glycoproteinaceous matrix of microalgal aplanospores. These results suggested that organic nitrogen was involved in the early development of P. sedebokerense on microalgal cell walls. In addition, most of the abundant amino acids from the algal host were the preferable ones for fungal growth (i.e., l-alanine, l-arginine, l-glutamic acid and glycine). However, P. sedebokerense cannot directly utilize methionine, and methionine or amino acid biosynthesis inhibitors (i.e., pyrimethanil and cyprodinil) completely abolished the parasitism process. These evidences revealed that methionine biosynthesis in the fungal pathogen was essential for the parasitism process, and methionine or amino acid biosynthesis inhibitors are effective for disease control.

Development of a whole-cell high-throughput phenotypic screen to identify inhibitors of mycobacterial amino acid biosynthesis.

Anti‐tubercular drug discovery continues to be dominated by whole‐cell high‐throughput screening campaigns, enabling the rapid discovery of new inhibitory chemical scaffolds. Target‐based screening is a popular approach to direct inhibitor discovery with a specified mode of action, eliminating the discovery of anti‐tubercular agents against unsuitable targets. Herein, a screening method has been developed using Mycobacterium bovis BCG to identify inhibitors of amino acid biosynthesis. The methodology was initially optimized using the known branched‐chain amino acid biosynthetic inhibitors metsulfuron‐methyl (MSM) and sulfometuron‐methyl (SMM), and subsequently, whole genome sequencing of resistant mutants and the use of over‐expressor strains confirming their mode of action. The GlaxoSmithKline compound library of small molecule inhibitors with known activity against Mycobacterium tuberculosis was then used to validate the screen. In this paper, we have shown that media supplementation with amino acids can rescue M bovis BCG from known amino acid synthesis inhibitors, MSM and SMM, in a pathway specific manner. The therapeutic potential of amino acid biosynthesis inhibitors emphasizes the importance of this innovative screen, enabling the discovery of compounds targeting a multitude of related essential biochemical pathways, without limiting drug discovery toward a single target.

Induction of the PDH bypass and upregulation of the ALDH7B4 in plants treated with herbicides inhibiting amino acid biosynthesis

Imazamox and glyphosate represent two classes of herbicides that inhibit the activity of acetohydroxyacid synthase in the branched-chain amino acid biosynthesis pathway and the activity of 5-enolpyruvylshikimate-3-phosphate synthase in the aromatic amino acid biosynthesis pathway, respectively. However, it is still unclear how imazamox and glyphosate lead to plant death. Both herbicides inhibit amino-acid biosynthesis and were found to induce ethanol fermentation in plants, but an Arabidopsis mutant deficient in alcohol dehydrogenase 1 was neither more susceptible nor more resistant than the wild-type to the herbicides. In this study, we investigated the effects of the amino acid biosynthesis inhibitors, imazamox and glyphosate, on the pyruvate dehydrogenase bypass reaction and fatty acid metabolism in A. thaliana. We found that the pyruvate dehydrogenase bypass was upregulated following the treatment by the two herbicides. Our results suggest that the Arabidopsis aldehyde dehydrogenase 7B4 gene might be participating in the pyruvate dehydrogenase bypass reaction. We evaluated the potential role of the aldehyde dehydrogenase 7B4 upon herbicide treatment in the plant defence mechanism. Plants that overexpressed the ALDH7B4 gene accumulated less soluble sugars, starch, and fatty acids and grew better than the wild-type after herbicide treatment. We discuss how the upregulation of the ALDH7B4 alleviates the effects of the herbicides, potentially through the detoxification of the metabolites produced in the pyruvate dehydrogenase bypass.

Branched-chain amino acid biosynthesis inhibitors: Herbicide efficacy is associated with an induced carbon–nitrogen imbalance

Acetolactate synthase (ALS; EC 4.1.3.18) and ketol-acid reductoisomerase (KARI; EC 1.1.1.86) are two consecutive enzymes in the biosynthesis of branched-chain amino acids. Several commercial herbicides inhibit ALS as their primary site of action. KARI has also attracted attention as a potential target for herbicides. Although potent and selective inhibitors of KARI have been discovered, these inhibitors display less herbicidal activity than ALS-inhibiting herbicides. To obtain a better understanding of these findings, we have compared the physiological effects induced in pea plants after KARI or ALS inhibition. Although, both types of inhibitors induce growth arrest and photosynthesis inhibition, plant death occurs more rapidly under ALS inhibition than KARI inhibition. Carbohydrates accumulated in the leaves and roots following treatments with both inhibitors. The carbohydrate accumulation in the leaves occurred as a consequence of a decrease in sink strength. In contrast, the free amino acid content was only affected through ALS inhibition. These results indicate that although KARI and ALS inhibition block the same biosynthetic pathway and exert common effects on carbon metabolism, nitrogen metabolism is more affected via ALS than KARI inhibition. Thus, metabolic alterations in nitrogen metabolism induced through ALS inhibitors might contribute to the increased efficacy of these chemicals as herbicides.

Impairment of carbon metabolism induced by the herbicide glyphosate

The herbicide glyphosate reduces plant growth and causes plant death by inhibiting the biosynthesis of aromatic amino acids. The objective of this work was to determine whether glyphosate-treated plants show a carbon metabolism pattern comparable to that of plants treated with herbicides that inhibit branched-chain amino acid biosynthesis. Glyphosate-treated plants showed impaired carbon metabolism with an accumulation of carbohydrates in the leaves and roots. The growth inhibition detected after glyphosate treatment suggested impaired metabolism that impedes the utilization of available carbohydrates or energy at the expected rate. These effects were common to both types of amino acid biosynthesis inhibitors. Under aerobic conditions, ethanolic fermentative metabolism was enhanced in the roots of glyphosate-treated plants. This fermentative response was not related to changes in the respiratory rate or to a limitation of the energy charge. This response, which was similar for both types of herbicides, might be considered a general response to stress conditions.

Herbicidal inhibitors of amino acid biosynthesis and herbicide-tolerant crops

Acetohydroxyacid synthase (AHAS) inhibitors interfere with branched-chain amino acid biosynthesis by inhibiting AHAS. Glyphosate affects aromatic amino acid biosynthesis by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Glufosinate inhibits glutamine synthetase and blocks biosynthesis of glutamine. AHAS gene variants that confer tolerance to AHAS inhibitors have been discovered in plants through selection or mutagenesis. Imidazolinone-tolerant crops have been commercialized based on these AHAS gene variants. A modified maize EPSPS gene and CP4-EPSPS gene from Agrobacterium sp. have been used to transform plants for target-based tolerance to glyphosate. A gox gene isolated from Ochrobactrum anthropi has also been employed to encode glyphosate oxidoreductase to detoxify glyphosate in plants. Glyphosate-tolerant crops with EPSPS transgene alone or both EPSPS and gox transgenes have been commercialized. Similarly, bar and pat genes isolated from Streptomyces hygroscopicus and S. viridochromogenes, respectively, have been inserted into plants to encode phosphinothricin N-acetyltransferase to detoxify glufosinate. Glufosinate-tolerant crops have been commercialized using one of these two transgenes.

ASM Conference ?Integrating Metabolism and Genomics?, Montreal, Quebec, Canada, 30 April?3 May, 2004

The Conference “Integrating Metabolism and Genomics” (IMAGE ) was organized by the American Society for Microbiology (ASM) and took place from April 30 to May 3, 2004, in a hotel in Montreal, Quebec, Canada. The Conference IMAGE provided a context for understanding the interface between genomics and metabolism in a large variety of microorganisms, illustrating nicely the potential, the challenges and the limitations of the post-genomics approaches. Because no parallel sessions were organized, the conference provided a real opportunity to learn about the recent genomics-guided developments obtained in a variety of microbiological systems beyond the own field of interest. The Conference brought together 175 scientists; one half from outside de USA (20% were Canadian) and 16% from corporate/industry. The format of ASM Conferences, focused on topics of scientific relevance, encourages interactive exchange and the participation of graduate students and post-docs. For IMAGE, ASM had awarded travel grants to 19 graduate students and new post-docs; nevertheless, this was an expensive meeting. The scientific program was organized in seven plenary sessions, with five presentations each (two of them selected among the posters) and two poster sessions. Session II was fully dedicated to the yeast Saccharomyces cerevisiae and all the sessions were of unquestionable interest to the community involved in yeast research or dedicated to any other microbial system in this new field of genomics-guided research. Robert La Rossa (DuPont de Nemours & Company, Wilmington, DE), who belongs to the ASM Conferences Committee and was one of the Conference organizers, opened this first session, illustrating the promises and limitations derived from the gene expression profile work carried out. Among the examples provided were the changes occurring in S. cerevisiae genome-wide expression caused by treatment with the herbicide sulfometuron methyl (SM), an inhibitor of amino acid biosynthesis. A potential link between SM sensitivity and ergosterol …

Global expression profiling of yeast treated with an inhibitor of amino acid biosynthesis, sulfometuron methyl.

The expression pattern of 1,529 yeast genes in response to sulfometuron methyl (SM) was analyzed by DNA microarray technology. SM, a potent herbicide, inhibits acetolactate synthase, a branched-chain amino acid biosynthetic enzyme. Exposure of yeast cells to 0.2 microg/ml SM resulted in 40% growth inhibition, a Gcn4p-mediated induction of genes involved in amino acid and cofactor biosynthesis, and starvation response. The accumulation of intermediates led to the induction of stress response genes and the repression of genes involved in carbohydrate metabolism, nucleotide biosynthesis, and sulfur assimilation. Extended exposure to SM led to a relaxation of the initial response and induction of sugar transporter and ergosterol biosynthetic genes, as well as repression of histone and lipid metabolic genes. Exposure to 5 microg/ml SM resulted in >98% growth inhibition and stimulated a similar initial expression change, but with no relaxation after extended exposure. Instead, more stress response and DNA damage repair genes become induced, suggesting a serious cellular consequence. Other salient features of metabolic regulation, such as the coordinated expression of cofactor biosynthetic genes with amino acid biosynthetic ones, were evident from our data. A potential link between SM sensitivity and ergosterol metabolism was uncovered by expression profiling and confirmed by genetic analysis.

Removal of mite allergens from blankets: Comparison of dry cleaning and hot water washing

1. Barry G, Kishore G, Padgette S, et al. Inhibitors of amino acid biosynthesis: strategies for imparting glyphosate tolerance to crop plants. In: Singh BK, Flores HE, Shannon JC, eds. Biosynthesis and molecular regulation of amino acids in plants. Rockville, Maryland: American Society of Plant Physiologists, 1992:139-45. 2. Padgette SR, Re DB, Barry GF, et al. New weed control opportunities: development of soybeans with a Roundup Ready TM gene. In: Duke SO, ed. Herbicide-resistant crops: agricultural economic, environmental, regulatory, and technological aspects. CRC Press, 1994 (in press). 3. Burks AW, Brooks JR, Sampson HA. Allergenicity of major component proteins of soybean determined by enzyme linked immunosorbent assay (ELISA) and immunoblotting in children with atopic dermatitis and positive soy challenges. J ALLERGY CLIN IMMUNOL 1988;81:1135-42. 4. Thanh VH, Shibasaki K. Major proteins of soybean seeds: a straight forward fractionation and their characterization. J Agri Food Chem 1976;24:1117-21. 5. Ogawa F, Tsuji H, Bando N, et al. Identification of the soybean allergenic protein, Gly m Bd 30K, with the soybean seed 34-kDa oil-body associated protein. Biosci Biotech Biochem 1993;57:1030-3.

The Development of Herbicide Resistant Crops

(…) Here we review recent work in the development of herbicide-resistant crops. A list of the herbicides for which these efforts have been initiated, along with their structures and their primary targets, is given in Table 1. We present examples of the introduction of herbicide resistance into crop plants by several different techniques, the status of development of herbicide-resistant cultivars, and future prospects for such work. (…) Contents introduction: Genetics in Agriculture, Herbicides in Agriculture. Plants resistant to amino acid biosynthesis inhibitors: Sulfonylureas and Imidazolinones, Glyphosate, Phosphinothricin. Plants resistant to photosynthesis inhibitors: Atrazine, Bromoxynil

The Saccharomyces cerevisiae ARO1 gene An example of the co-ordinate regulation of five enzymes on a single biosynthetic pathway

The ARO1 gene of Saccharomyces cerevisiae encodes the arom multifunctional enzyme. Specific inhibitors of amino acid biosynthesis have been used to obtain evidence that expression of a cloned ARO1 gene is regulated in response to amino acid limitation. Northern blot analysis and sequence studies indicate that ARO1 is regulated by the well characterised S. cerevisiae ‘general control’ mechanism. This provides a very economical means of simultaneously tailoring the synthesis of five shikimate pathway enzymes to the needs of the cell.

Amino acid biosynthesis inhibitors as herbicides.

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Sulfonylurea herbicides as inhibitors of amino acid biosynthesis in plants

Physiological, biochemical and genetic studies indicate that the sulfonylurea herbicides inhibit the enzyme acetolactate synthase. This enzyme catalyses the first reaction in the synthesis of the amino acids valine, leucine and isoleucine in plants and microorganisms. The elucidation of the mechanism of action of herbicides such as the sulfonylureas not only has implications on the rational design of herbicides but also on the development of herbicide-resistant crops through genetic engineering.