Protocatechuate hydroxylase is a novel group A flavoprotein monooxygenase with a unique substrate recognition mechanism.

Para-hydroxybenzoate hydroxylase (PHBH) is a group A flavoprotein monooxygenase that hydroxylates p-hydroxybenzoate to protocatechuate (PCA). Despite intensive studies of Pseudomonas aeruginosa p-hydroxybenzoate hydroxylase (PaPobA), the catalytic reactions of extremely diverse putative PHBH isozymes remain unresolved. We analyzed the phylogenetic relationships of known and predicted PHBHs and identified eight divergent clades. Clade F contains a protein that lacks the critical amino acid residues required for PaPobA to generate PHBH activity. Among proteins in this clade, Xylophilus ampelinus PobA (XaPobA) preferred PCA as a substrate and is the first known natural PCA 5-hydroxylase (PCAH). Crystal structures and kinetic properties revealed similar mechanisms of substrate carboxy group recognition between XaPobA and PaPobA. The unique Ile75, Met72, Val199, Trp201, and Phe385 residues of XaPobA form the bottom of a hydrophobic cavity with a shape that complements the 3-and 4-hydroxy groups of PCA and its binding site configuration. An interaction between the δ-sulfur atom of Met210 and the aromatic ring of PCA is likely to stabilize XaPobA-PCA complexes. The 4-hydroxy group of PCA forms a hydrogen bond with the main chain carbonyl of Thr294. These modes of binding constitute a novel substrate recognition mechanism that PaPobA lacks. This mechanism characterizes XaPobA and sheds light on the diversity of catalytic mechanisms of PobA-type PHBHs and group A flavoprotein monooxygenases.

[A Case of CA19-9-Producing Gastric Cancer with Recurrence of Lymph Node Metastasis That Achieved Clinical CR in Fourth-Line CapeOX Therapy].

A 74-year-old man underwent a distal gastrectomy for advanced gastric cancer. After surgical treatment, lymph node metastasis was observed during postoperative adjuvant S-1 chemotherapy. Weekly PTX plus RAM as second-line therapy and nivolumab as third-line therapy was administered, but lymph node enlarged and CA19-9 remained high. Therefore, 6 courses of CapeOX was administered as the fourth-line therapy, and CA19-9 markedly decreased and normalized, and CT showed marked reduction in all lymph nodes. After 12 courses, CT scan showed lymph node shrinkage and PET-CT scan showed no FDG uptake, and the patient was diagnosed as clinical complete response(cCR). Six months later, maintaining cCR. We experienced a case in which the introduction of CapeOX therapy resulted in a remarkable response to recurrence of lymph nodes after gastric cancer during S-1 therapy.

Inactivation of axon guidance molecule netrin-1 in human colorectal cancer by an epigenetic mechanism.

Netrin-1, the protein product of the NTN1 gene, is an axon guidance molecule implicated in regulation of cell survival and tumorigenesis. Expression of the netrin-1 receptors deleted in colorectal cancer (DCC) and uncoordinated 5 homolog (UNC5H) is frequently silenced in colorectal cancer (CRC) by either loss of heterozygosity or epigenetic mechanisms. However, netrin-1 expression and regulation in CRC are mostly unknown. Here, we report that NTN1 expression is significantly reduced in most CRC tissues compared to the adjacent normal intestinal mucosa, and that NTN1 DNA methylation is significantly higher in CRCs (24.6%) than in the adjacent normal intestinal mucosa (4.0%). In 6 CRC cell lines, NTN1 expression is low. Treatment with 5-Aza-2'-deoxycytidine increased expression of NTN1 in CRC cell lines, indicating that DNA methylation represses NTN1 transcription in CRCs. NTN1 DNA hypermethylation was significantly associated with advanced CRC disease. Median netrin-1 serum levels were significantly decreased in CRC patients (330.1 pg/mL) compared with normal individuals (438.6 pg/mL). Our results suggest that netrin-1 is a candidate biomarker for CRC.

Carboxypeptidase G and pterin deaminase metabolic pathways degrade folic acid in Variovorax sp. F1.

BACKGROUND: Folic acid (FA) is a synthetic vitamin (B9) and the oxidized form of a metabolic cofactor that is essential for life. Although the biosynthetic mechanisms of FA are established, its environmental degradation mechanism has not been fully elucidated. The present study aimed to identify bacteria in soil that degrade FA and the mechanisms involved. RESULTS: We isolated the soil bacterium Variovorax sp. F1 from sampled weed rhizospheres in a grassland and investigated its FA degradation mechanism. Cultured Variovorax sp. F1 rapidly degraded FA to pteroic acid (PA), indicating that FA hydrolysis to PA and glutamate. We cloned the carboxypeptidase G (CPG) gene and found widely distributed paralogs within the Variovorax genus. Recombinant CPG preferred FA and deaminofolic acid as substrates, indicating its involvement in FA degradation by Variovorax. Prolonged culture of Variovorax sp. F1 resulted in decreased rates of deaminofolic acid (DFA) and deaminopteroic acid (DPA) accumulation. This indicated that the deamination reaction also comprised a route of FA degradation. We also identified an F1 gene that was orthologous to the pterin deaminase gene (Arad3529) of Agrobacterium radiobacter. The encoded protein deaminated FA and PA to DFA and DPA, which was consistent with the deamination activity of FA and PA in bacterial cell-free extracts. CONCLUSION: We discovered that the two enzymes required for FA degradation pathways in isolates of Variovorax sp. F1 comprise CPG and pterin deaminase, and that DFA and PA are intermediates in the generation of DPA.

Symbiotic riboflavin degradation by Microbacterium and Nocardioides bacteria.

Unlike its biosynthetic mechanisms and physiological function, current understanding of riboflavin degradation in soil is limited to a few bacteria that decompose it to lumichrome. Here, we isolated six Microbacterium and three Nocardioides strains. These strains utilized riboflavin and lumichrome, respectively, as carbon sources. Among these strains, we identified Microbacterium paraoxydans R16 (R16) and Nocardioides nitrophenolicus L16 (L16), which were isolated form the same enrichment culture. Co-cultured R16 and L16 reconstituted a riboflavin-degrading interspecies consortium, in which the R16 strain degraded riboflavin to lumichrome and ᴅ-ribose. The L16 strain utilized the lumichrome as a carbon source, indicating that R16 is required for L16 to grow in the consortium. Notably, rates of riboflavin degradation and growth were increased in co-cultured, compared with monocultured R16 cells. These results indicated that a beneficial symbiotic interaction between M. paraoxydans R16 and N. nitrophenolicus L16 results in the ability to degrade riboflavin.

Glycerol metabolism and its regulation in lactic acid bacteria.

Glycerol is one of the most important substrates involved in phospholipid biosynthesis, along with dihydroxyacetone phosphate (DHAP) as an intermediate of glycolysis. Organisms produce glycerol 3-phosphate (G3P) from endogenous DHAP and/or exogenous glycerol to synthesize glycerophospholipids from G3P. On the other hand, organisms can utilize glycerol as a carbon source to generate adenosine triphosphate (ATP). Glycerol metabolism in microorganisms has been investigated for > 50 years. The main research targets have been four bacteria that can utilize glycerol efficiently: Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, and Enterococcus faecalis. E. coli, E. aerogenes, and K. pneumoniae are gram-negative bacteria in the Enterobacteriales order of the class γ-Proteobacteria. In contrast, E. faecalis is a gram-positive bacterium in the Lactobacillales order of the class Bacilli, which are well-known lactic acid bacteria (LAB). Therefore, the glycerol metabolism of E. faecalis is characterized by the properties of both gram-positive bacteria and LAB, which substantially differ from the other three bacteria. As glycerophospholipids are essential for LAB, genes encoding the enzyme for glycerol metabolism (including G3P synthesis) are broadly detected from various LAB. However, these LAB's classification and trend remained unclear until now, along with each LAB's ability to utilize glycerol. Hence, the present review summarizes LAB's glycerol metabolic pathway and regulation mechanism based on the distribution of the genes involved in those and discusses the peculiarities of glycerol metabolism in E. faecalis.

Correction to: Glycerol metabolism and its regulation in lactic acid bacteria.

The original publication of this paper contains some errors.

Lactic acid fermentation is the main aerobic metabolic pathway in Enterococcus faecalis metabolizing a high concentration of glycerol.

Bacterial lactate production by fermentative lactate dehydrogenase is generally activated under anaerobic conditions. However, when the Enterococcus faecalis strain W11 was cultured with a high concentration of glycerol (1.0 M), but not with glucose, up to 0.95 M L-lactate was produced from 1.0 M glycerol via the fermentative L-lactate dehydrogenase (LdhL1) reaction despite the abundant supply of oxygen. To understand the underlying mechanism, transcription, metabolic products, and intracellular NADH/total NAD (tNAD) ratio of W11 were analyzed. The ldhL1 transcription was constitutive and not markedly affected by dissolved oxygen level or NADH/tNAD ratio. Conversely, gene transcription and enzyme activities related to other pyruvate metabolic pathways, namely the acetoin, acetate, and ethanol production pathways, in W11 utilizing 1.0 M glycerol tended to be downregulated or inactivated by a high NADH/tNAD ratio or supply of oxygen. These findings indicated that the amount and yield of L-lactate depended on the activity levels of other metabolic pathways and that lactic acid fermentation was the main aerobic metabolic pathway in W11 utilizing glycerol at a high concentration. This phenomenon enabled W11 to produce up to 1.50 M and 1.15 M L-lactate from glycerol and crude glycerol with a high yield, respectively, and these production amounts were higher than those in previous studies.

[Four Cases of Locally Advanced Colorectal Cancer Resected after Neoadjuvant Chemotherapy with mFOLFOX6 plus Bevacizumab].

We describe 4 cases of locally advanced colorectal cancer resected successfully after neoadjuvant chemotherapy(NAC) conducted between April 2015 and August 2016. The NAC with mFOLFOX6 plus bevacizumab was performed after ileostomy for prevention of obstruction, because of tumor invasion into other organs. After chemotherapy, we could perform resection and avoid invasive surgery in either cases.

A novel A3 group aconitase tolerates oxidation and nitric oxide.

Achromobacter denitrificans YD35 is an NO2 (-)-tolerant bacterium that expresses the aconitase genes acnA3, acnA4, and acnB, of which acnA3 is essential for growth tolerance against 100 mm NO2 (-). Atmospheric oxygen inactivated AcnA3 at a rate of 1.6 × 10(-3) min(-1), which was 2.7- and 37-fold lower compared with AcnA4 and AcnB, respectively. Stoichiometric titration showed that the [4Fe-4S](2+) cluster of AcnA3 was more stable against oxidative inactivation by ferricyanide than that of AcnA4. Aconitase activity of AcnA3 persisted against high NO2 (-) levels that generate reactive nitrogen species with an inactivation rate constant of k = 7.8 × 10(-3) min(-1), which was 1.6- and 7.8-fold lower than those for AcnA4 and AcnB, respectively. When exposed to NO2 (-), the acnA3 mutant (AcnA3Tn) accumulated higher levels of cellular citrate compared with the other aconitase mutants, indicating that AcnA3 is a major producer of cellular aconitase activity. The extreme resistance of AcnA3 against oxidation and reactive nitrogen species apparently contributes to bacterial NO2 (-) tolerance. AcnA3Tn accumulated less cellular NADH and ATP compared with YD35 under our culture conditions. The accumulation of more NO by AcnA3Tn suggested that NADH-dependent enzymes detoxify NO for survival in a high NO2 (-) milieu. This novel aconitase is distributed in Alcaligenaceae bacteria, including pathogens and denitrifiers, and it appears to contribute to a novel NO2 (-) tolerance mechanism in this strain.

Identification and characterization of natural microbial products that alter the free d-aspartate content of mammalian cells.

Mammalian cells possess the molecular apparatus necessary to take up, degrade, synthesize, and release free d-aspartate, which plays an important role in physiological functions within the body. Here, biologically active microbial compounds and pre-existing drugs were screened for their ability to alter the intracellular d-aspartate level in mammalian cells, and several candidate compounds were identified. Detailed analytical studies suggested that two of these compounds, mithramycin A and geldanamycin, suppress the biosynthesis of d-aspartate in cells. Further studies suggested that these compounds act at distinct sites within the cell. These compounds may advance our current understanding of biosynthesis of d-aspartate in mammals, a whole picture of which remains to be disclosed.

[A Case of Rectal Cancer with Unresectable Liver Metastasis Responding to Rechallenge with FOLFIRI].

A 63-year-old man underwent low anterior resection for rectal cancer.A synchronous liver metastasis located in segment 8 was 12 cm in diameter and unresectable due to its proximity to the inferior vena cava(IVC).The postoperative pathological findings revealed a T3(SS), N0, M1(liver)Stage IV tumor, and wild type K-RAS was expressed.We chose FOLFIRI plus cetuximab(Cmab)for first-line chemotherapy.After 6 courses, we changed the molecular target drug from Cmab to bevacizumab( Bmab)because the liver metastasis remained unresectable.The patient had long-term stable disease(SD)for approximately 30 months with the FOLFIRI-based regimen.We then changed the regimen to mFOLFOX6 plus Bmab for second-line, Cmab for third-line, and trifluridine/tipiracil hydrochloride for fourth-line chemotherapy to treat progressive disease(PD).After treatment with these chemotherapies, the patient wished to continue treatment.We restarted FOLFIRI plus Bmab for fifth-line chemotherapy as his general condition was still good.Consequently, his tumor markers levels decreased with stabilization of the disease on CT scans, and he continued therapy for 6 months while maintaining a good quality of life.This case suggested that rechallenge with anti-cancer agents could be effective and improve the prognosis of colorectal cancer patients after using all key drugs.

Hydrazidase, a novel amidase signature enzyme that hydrolyzes acylhydrazides.

The degradation mechanisms of natural and artificial hydrazides have been elucidated. Here we screened and isolated bacteria that utilize the acylhydrazide 4-hydroxybenzoic acid 1-phenylethylidene hydrazide (HBPH) from soils. Physiological and phylogenetic studies identified one bacterium as Microbacterium sp. strain HM58-2, from which we purified intracellular hydrazidase, cloned its gene, and prepared recombinant hydrazidase using an Escherichia coli expression system. The Microbacterium sp. HM58-2 hydrazidase is a 631-amino-acid monomer that was 31% identical to indoleacetamide hydrolase isolated from Bradyrhizobium japonicum. Phylogenetic studies indicated that the Microbacterium sp. HM58-2 hydrazidase constitutes a novel hydrazidase group among amidase signature proteins that are distributed within proteobacteria, actinobacteria, and firmicutes. The hydrazidase stoichiometrically hydrolyzed the acylhydrazide residue of HBPH to the corresponding acid and hydrazine derivative. Steady-state kinetics showed that the enzyme hydrolyzes structurally related 4-hydrozybenzamide to hydroxybenzoic acid at a lower rate than HBPH, indicating that the hydrazidase prefers hydrazide to amide. The hydrazidase contains the catalytic Ser-Ser-Lys motif that is conserved among members of the amidase signature family; it shares a catalytic mechanism with amidases, according to mutagenesis findings, and another hydrazidase-specific mechanism must exist that compensates for the absence of the catalytic Ser residue. The finding that an environmental bacterium produces hydrazidase implies the existence of a novel bacterial mechanism of hydrazide degradation that impacts its ecological role.

L-lactate production from biodiesel-derived crude glycerol by metabolically engineered Enterococcus faecalis: cytotoxic evaluation of biodiesel waste and development of a glycerol-inducible gene expression system.

Biodiesel waste is a by-product of the biodiesel production process that contains a large amount of crude glycerol. To reuse the crude glycerol, a novel bioconversion process using Enterococcus faecalis was developed through physiological studies. The E. faecalis strain W11 could use biodiesel waste as a carbon source, although cell growth was significantly inhibited by the oil component in the biodiesel waste, which decreased the cellular NADH/NAD(+) ratio and then induced oxidative stress to cells. When W11 was cultured with glycerol, the maximum culture density (optical density at 600 nm [OD600]) under anaerobic conditions was decreased 8-fold by the oil component compared with that under aerobic conditions. Furthermore, W11 cultured with dihydroxyacetone (DHA) could show slight or no growth in the presence of the oil component with or without oxygen. These results indicated that the DHA kinase reaction in the glycerol metabolic pathway was sensitive to the oil component as an oxidant. The lactate dehydrogenase (Ldh) activity of W11 during anaerobic glycerol metabolism was 4.1-fold lower than that during aerobic glycerol metabolism, which was one of the causes of low l-lactate productivity. The E. faecalis pflB gene disruptant (Δpfl mutant) expressing the ldhL1LP gene produced 300 mM l-lactate from glycerol/crude glycerol with a yield of >99% within 48 h and reached a maximum productivity of 18 mM h(-1) (1.6 g liter(-1) h(-1)). Thus, our study demonstrates that metabolically engineered E. faecalis can convert crude glycerol to l-lactate at high conversion efficiency and provides critical information on the recycling process for biodiesel waste.

NO-inducible nitrosothionein mediates NO removal in tandem with thioredoxin.

Nitric oxide (NO) is a toxic reactive nitrogen species that induces microbial adaption mechanisms. Screening a genomic DNA library identified a new gene, ntpA, that conferred growth tolerance upon Aspergillus nidulans against exogenous NO. The gene encoded a cysteine-rich 23-amino-acid peptide that reacted with NO and S-nitrosoglutathione to generate an S-nitrosated peptide. Disrupting ntpA increased amounts of cellular S-nitrosothiol and NO susceptibility. Thioredoxin and its reductase denitrosated the S-nitrosated peptide, decreased cellular S-nitrosothiol and conferred tolerance against NO, indicating peptide-mediated catalytic NO removal. The peptide binds copper(I) in vitro but is dispensable for metal tolerance in vivo. NO but not metal ions induced production of the peptide and ntpA transcripts. We discovered that the thionein family of peptides has NO-related functions and propose that the new peptide be named NO-inducible nitrosothionein (iNT). The ubiquitous distribution of iNT-like polypeptides constitutes a potent NO-detoxifying mechanism that is conserved among various organisms.

[Experience of the Pharmacotherapy against Appendix and Sigmoid Colon Signet Ring Cell Carcinoma with the Peritoneal Dissemination].

We report 2 cases of signet ring cell carcinoma of the appendix and colon. Case 1: A 61-year-old man was admitted for lower abdominal pain. Colonoscopy revealed an elevated lesion in the orifice of the appendix. Signet ring cell carcinoma was diagnosed on biopsy. The surgical findings showed multiple peritoneal dissemination nodules, while the primary tumor was unresectable owing to extensive invasion into the retroperitoneum. The histopathological findings were signet ring cell carcinoma, T4b (retroperitoneum), NX, P3, Stage Ⅳ. Although the patient received 14 courses of treatment with S-1 as postoperative chemotherapy, he died of his illness at 32 postoperative months. Case 2: A 76-year-old man was admitted for abdominal pain. Perforation of the lower gastrointestinal tract was diagnosed on abdominal CT, and an emergency operation was performed. The surgical findings demonstrated a large number of peritoneal dissemination nodules, cecal invasion of a sigmoid tumor, and perforation of the ascending colon. The primary tumor was thought to be unresectable, and the perforated segment was resected. The histopathological findings were signet ring cell carcinoma, T4b (cecum), NX, P3, Stage Ⅳ. Although 11 courses of treatment using FOLFIRI+Bev were administered as postoperative chemotherapy, the patient died of his illness at 26 postoperative months.

[Clinicopathological Features and Outcomes of Treatment for HER2 Positive Gastric Cancer].

In March 2011, trastuzumab was approved for treating human epidermal growth factor receptor 2 (HER2) positive advanced gastric cancer (AGC) in Japan. Therefore, all patients with AGC should be evaluated for HER2 status. In this study, we analyzed the clinicopathological features and current status of treatment in HER2 positive gastric cancer. One hundred 6 gastric cancer patients were examined for HER2 expression in our hospital between March 2011 and August 2014. Sixteen patients (15.1%) were HER2 positive. There was no correlation between HER2 status and age, sex, and location of tumor; however, HER2 positivity was significantly more frequent in patients with intestinal type tumors and had a tendency towards being more frequent in patients with macroscopic types 0, 1 or 2. Trastuzumab was administered to 10 patients with HER2 positive AGC. The total number of doses of trastuzumab was 1 to 44 (median 7.5), and the therapeutic effect of trastuzumab combination chemotherapy was 1 patient with a complete response and 4 with a partial response. Adverse events due to trastuzumab were not observed. The incidence of HER2 over-expression was 15.1%, and trastuzumab combination chemotherapy was relatively safe and effective.

Pyruvate formate-lyase is essential for fumarate-independent anaerobic glycerol utilization in the Enterococcus faecalis strain W11.

Although anaerobic glycerol metabolism in Enterococcus faecalis requires exogenous fumarate for NADH oxidation, E. faecalis strain W11 can metabolize glycerol in the absence of oxygen without exogenous fumarate. In this study, metabolic end product analyses and reporter assays probing the expression of enzymes involved in pyruvate metabolism were performed to investigate this fumarate-independent anaerobic metabolism of glycerol in W11. Under aerobic conditions, the metabolic end products of W11 cultured with glycerol were similar to those of W11 cultured with glucose. However, when W11 was cultured anaerobically, most of the glucose was converted to l-lactate, but glycerol was converted to ethanol and formate. During anaerobic culture with glycerol, the expression of the l-lactate dehydrogenase and pyruvate dehydrogenase E1αß genes in W11 was downregulated, whereas the expression of the pyruvate formate-lyase (Pfl) and aldehyde/alcohol dehydrogenase genes was upregulated. These changes in the expression levels caused the change in the composition of end products. A pflB gene disruptant (Δpfl mutant) of W11 could barely utilize glycerol under anaerobic conditions, but the growth of the Δpfl mutant cultured with either glucose or dihydroxyacetone (DHA) under anaerobic conditions was the same as that of W11. Glucose metabolism and DHA generates one NADH molecule per pyruvate molecule, whereas glycerol metabolism in the dehydrogenation pathway generates two NADH molecules per pyruvate molecule. These findings demonstrate that NADH generated from anaerobic glycerol metabolism in the absence of fumarate is oxidized through the Pfl-ethanol fermentation pathway. Thus, Pfl is essential to avoid the accumulation of excess NADH during fumarate-independent anaerobic glycerol metabolism.

Achromobacter denitrificans strain YD35 pyruvate dehydrogenase controls NADH production to allow tolerance to extremely high nitrite levels.

We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2(-)) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2(-)-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2(-) tolerance. A mutant in which the pdh gene cluster was disrupted (Δpdh mutant) could not grow in the presence of 100 mM NO2(-). Nitrite decreased the cellular NADH/NAD(+) ratio and the cellular ATP level. These defects were more severe in the Δpdh mutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2(-)-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the TCA cycle, compensated for these defects caused by disruption of the pdh gene cluster and those caused by NO2(-). These findings demonstrate a link between NO2(-) tolerance and pyruvate/acetate metabolism through the TCA cycle. The TCA cycle mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2(-)-tolerating mechanism in this strain.

The Metabolic Regulation of Amino Acid Synthesis Counteracts Reactive Nitrogen Stress via Aspergillus nidulans Cross-Pathway Control.

Nitric oxide (NO) is a natural reactive nitrogen species (RNS) that alters proteins, DNA, and lipids and damages biological activities. Although microorganisms respond to and detoxify NO, the regulation of the cellular metabolic mechanisms that cause cells to tolerate RNS toxicity is not completely understood. We found that the proline and arginine auxotrophic proA5 and argB2 mutants of the fungus Aspergillus nidulans require more arginine and proline for normal growth under RNS stress that starves cells by accumulating fewer amino acids. Fungal transcriptomes indicated that RNS stress upregulates the expression of the biosynthetic genes required for global amino acids, including proline and arginine. A mutant of the gene disruptant, cpcA, which encodes the transcriptional regulation of the cross-pathway control of general amino acid synthesis, did not induce these genes, and cells accumulated fewer amino acids under RNS stress. These results indicated a novel function of CpcA in the cellular response to RNS stress, which is mediated through amino acid starvation and induces the transcription of genes for general amino acid synthesis. Since CpcA also controls organic acid biosynthesis, impaired intermediates of such biosynthesis might starve cells of amino acids. These findings revealed the importance of the mechanism regulating amino acid homeostasis for fungal responses to and survival under RNS stress.