TmcA functions as a lysine 2-hydroxyisobutyryltransferase to regulate transcription

Protein lysine 2-hydroxyisobutyrylation (Khib) has recently been shown to play a critical role in the regulation of cellular processes. However, the mechanism and functional consequence of Khib in prokaryotes remain unclear. Here we report that TmcA, an RNA acetyltransferase, functions as a lysine 2-hydroxyisobutyryltransferase in the regulation of transcription. We show that TmcA can effectively catalyze Khib both in vitro and intracellularly, and that R502 is a key site for the Khib catalytic activity of TmcA. Using quantitative proteomics, we identified 467 endogenous candidates targeted by TmcA for Khib in Escherichia coli. Interestingly, we demonstrate that TmcA can specifically modulate the DNA-binding activity of H-NS, a nucleoid-associated protein, by catalysis of Khib at K121. Furthermore, this TmcA-targeted Khib regulates transcription of acid-resistance genes and enhances E. coli survival under acid stress. Our study reveals transcription regulation mediated by TmcA-catalyzed Khib for bacterial acid resistance.

Transcriptional Regulation of Carboxylesterase 1 in Human Liver: Role of the Nuclear Receptor Subfamily 1 Group H Member 3 and Its Splice Isoforms

Carboxylesterase 1 (CES1) is the predominant carboxylesterase in the human liver, involved in metabolism of both xenobiotics and endogenous substrates. Genetic or epigenetic factors that alter CES1 activity or expression are associated with changes in drug response, lipid, and glucose homeostasis. However, the transcriptional regulation of CES1 in the human liver remains uncertain. By applying both the random forest and Sobol's Sensitivity Indices (SSI) to analyze existing liver RNA expression microarray data (GSE9588), we identified nuclear receptor subfamily 1 group H member 3 (NR1H3) liver X receptor (LXR)α as a key factor regulating constitutive CES1 expression. This model prediction was validated using small interfering RNA (siRNA) knockdown and CRISPR-mediated transcriptional activation of NR1H3 in Huh7 and HepG2 cells. We found that NR1H3's activation of CES1 is splice isoform-specific, namely that increased expression of the NR1H3-211 isoform increased CES1 expression whereas NR1H3-201 did not. Also, in human liver samples, expression of NR1H3-211 and CES1 are correlated, whereas NR1H3-201 and CES1 are not. This trend also occurs during differentiation of induced pluripotent stem cells (iPSCs) to hepatocytes, where only expression of the NR1H3-211 isoform parallels expression of CES1 Moreover, we found that treatment with the NR1H3 agonist T0901317 in HepG2 cells had no effect on CES1 expression. Overall, our results demonstrate a key role of NR1H3 in maintaining the constitutive expression of CES1 in the human liver. Furthermore, our results support that the effect of NR1H3 is splice isoform-specific and appears to be ligand independent. SIGNIFICANCE STATEMENT: Despite the central role of carboxylesterase 1 (CES1) in metabolism of numerous medications, little is known about its transcriptional regulation. This study identifies nuclear receptor subfamily 1 group H member 3 as a key regulator of constitutive CES1 expression and therefore is a potential target for future studies to understand interperson variabilities in CES1 activity and drug metabolism.

Tanycyte specific ablation of diacylglycerol lipase alpha stimulates the hypothalamic-pituitary-thyroid axis by decreasing the endocannabinoid mediated inhibition of TRH release

In addition to the hypophysiotropic thyrotropin-releasing hormone (TRH)-synthesizing neurons, a glial cell type, the tanycytes, also play a role in the regulation of the hypothalamic-pituitary-thyroid (HPT) axis. Tanycytes modulate the feedback regulation of the axis by regulating the local thyroid hormone availability in the median eminence where the hypophysiotropic axons terminate. Recently, we showed that tanycytes produce diacylglycerol lipase alpha (DAGLα), the synthesizing enzyme of the endocannabinoid 2-arachidonoylglycerol (2-AG) that inhibits the release of TRH from the hypophysiotropic terminals in median eminence explants. To determine the importance of the endocannabinoid production of tanycytes, adult male Rax-CreERT2//DAGLα^fl/fl mice were treated with tamoxifen to induce a tanycyte specific decrease of DAGLα expression (T-DAGLα KO). The effect of this genetic manipulation on the activity of the HPT axis was determined. Tanycyte specific decrease of DAGLα expression resulted in an approximately 2-fold increase of TSHβ mRNA level that was accompanied by increased levels of circulating free T4. The TRH mRNA level was, however, not influenced by the genetic manipulation. In addition to the effects on the HPT axis, the T-DAGLα KO mice showed increased fat mass ratio and decreased blood glucose levels. These data indicate that when endocannabinoid release of tanycytes is decreased, the disinhibition of the TRH release induces increased TSH synthesis and higher circulating T4 levels. Thus it suggests that in wild-type mice, tanycytes exert a tonic inhibitory effect on the TRH release of hypophysiotropic axons. Furthermore, the endocannabinoid release of tanycytes also influences glucose homeostasis and fat deposition.

Structure and RNA template requirements of Arabidopsis RNA-DEPENDENT RNA POLYMERASE 2

RNA-dependent RNA polymerases play essential roles in RNA-mediated gene silencing in eukaryotes. In Arabidopsis, RNA-DEPENDENT RNA POLYMERASE 2 (RDR2) physically interacts with DNA-dependent NUCLEAR RNA POLYMERASE IV (Pol IV) and their activities are tightly coupled, with Pol IV transcriptional arrest, induced by the nontemplate DNA strand, somehow enabling RDR2 to engage Pol IV transcripts and generate double-stranded RNAs. The double-stranded RNAs are then released from the Pol IV-RDR2 complex and diced into short-interfering RNAs that guide RNA-directed DNA methylation and silencing. Here we report the structure of full-length RDR2, at an overall resolution of 3.1 Å, determined by cryoelectron microscopy. The N-terminal region contains an RNA-recognition motif adjacent to a positively charged channel that leads to a catalytic center with striking structural homology to the catalytic centers of multisubunit DNA-dependent RNA polymerases. We show that RDR2 initiates 1 to 2 nt internal to the 3' ends of its templates and can transcribe the RNA of an RNA/DNA hybrid, provided that 9 or more nucleotides are unpaired at the RNA's 3' end. Using a nucleic acid configuration that mimics the arrangement of RNA and DNA strands upon Pol IV transcriptional arrest, we show that displacement of the RNA 3' end occurs as the DNA template and nontemplate strands reanneal, enabling RDR2 transcription. These results suggest a model in which Pol IV arrest and backtracking displaces the RNA 3' end as the DNA strands reanneal, allowing RDR2 to engage the RNA and synthesize the complementary strand.

Response of physiological parameters in Dionaea muscipula J. Ellis teratomas transformed with rolB oncogene

BACKGROUND

Plant transformation with rol oncogenes derived from wild strains of Rhizobium rhizogenes is a popular biotechnology tool. Transformation effects depend on the type of rol gene, expression level, and the number of gene copies incorporated into the plant's genomic DNA. Although rol oncogenes are known as inducers of plant secondary metabolism, little is known about the physiological response of plants subjected to transformation.

RESULTS

In this study, the physiological consequences of rolB oncogene incorporation into the DNA of Dionaea muscipula J. Ellis was evaluated at the level of primary and secondary metabolism. Examination of the teratoma (transformed shoots) cultures of two different clones (K and L) showed two different strategies for dealing with the presence of the rolB gene. Clone K showed an increased ratio of free fatty acids to lipids, superoxide dismutase activity, synthesis of the oxidised form of glutathione, and total pool of glutathione and carotenoids, in comparison to non-transformed plants (control). Clone L was characterised by increased accumulation of malondialdehyde, proline, activity of superoxide dismutase and catalase, total pool of glutathione, ratio of reduced form of glutathione to oxidised form, and accumulation of selected phenolic acids. Moreover, clone L had an enhanced ratio of total triglycerides to lipids and accumulated saccharose, fructose, glucose, and tyrosine.

CONCLUSIONS

This study showed that plant transformation with the rolB oncogene derived from R. rhizogenes induces a pleiotropic effect in plant tissue after transformation. Examination of D. muscipula plant in the context of transformation with wild strains of R. rhizogenes can be a new source of knowledge about primary and secondary metabolites in transgenic organisms.

Loss of Dihydroxyacid Dehydratase Induces Auxotrophy in Bacillus anthracis

Anthrax disease is caused by infection with the bacteria Bacillus anthracis which, if left untreated, can result in fatal bacteremia and toxemia. Current treatment for infection requires prolonged administration of antibiotics. Despite this, inhalational and gastrointestinal anthrax still result in lethal disease. By identifying key metabolic steps that B. anthracis uses to grow in host-like environments, new targets for antibacterial strategies can be identified. Here, we report that the ilvD gene, which encodes dihydroxyacid dehydratase in the putative pathway for synthesizing branched chain amino acids, is necessary for B. anthracis to synthesize isoleucine de novo in an otherwise limiting microenvironment. We observed that ΔilvD B. anthracis cannot grow in media lacking isoleucine, but growth is restored when exogenous isoleucine is added. In addition, ΔilvD bacilli are unable to utilize human hemoglobin or serum albumin to overcome isoleucine auxotrophy, but can when provided with the murine forms. This species-specific effect is due to the lack of isoleucine in human hemoglobin. Furthermore, even when supplemented with physiological levels of human serum albumin, apotransferrin, fibrinogen, and IgG, the ilvD knockout strain grew poorly relative to nonsupplemented wild type. In addition, comparisons upon infecting humanized mice suggest that murine hemoglobin is a key source of isoleucine for both WT and ΔilvD bacilli. Further growth comparisons in murine and human blood show that the auxotrophy is detrimental for growth in human blood, not murine. This report identifies ilvD as necessary for isoleucine production in B. anthracis, and that it plays a key role in allowing the bacilli to effectively grow in isoleucine poor hosts. IMPORTANCE Anthrax disease, caused by B. anthracis, can cause lethal bacteremia and toxemia, even following treatment with antibiotics. This report identifies the ilvD gene, which encodes a dihydroxyacid dehydratase, as necessary for B. anthracis to synthesize the amino acid isoleucine in a nutrient-limiting environment, such as its mammalian host. The use of this strain further demonstrated a unique species-dependent utilization of hemoglobin as an exogenous source of extracellular isoleucine. By identifying mechanisms that B. anthracis uses to grow in host-like environments, new targets for therapeutic intervention are revealed.

Genomic analysis of the carboxylesterase family in the salmon louse (Lepeophtheirus salmonis)

The pyrethroid deltamethrin and the macrocyclic lactone emamectin benzoate (EMB) are used to treat infestations of farmed salmon by parasitic salmon lice, Lepeophtheirus salmonis. While the efficacy of both compounds against Atlantic populations of the parasite has decreased as a result of the evolution of resistance, the molecular mechanisms of drug resistance in L. salmonis are currently not fully understood. The functionally diverse carboxylesterases (CaE) family includes members involved in pesticide resistance phenotypes of terrestrial arthropods. The present study had the objective to characterize the CaE family in L. salmonis and assess its role in drug resistance. L. salmonis CaE homologues were identified by homology searches in the parasite's transcriptome and genome. The transcript expression of CaEs predicted to be catalytically competent was studied using quantitative reverse-transcription PCR in drug susceptible and multi-resistant L. salmonis. The above strategy led to the identification of 21 CaEs genes/pseudogenes. Phylogenetic analyses assigned 13 CaEs to clades involved in neurodevelopmental signaling and cell adhesion, while three sequences were predicted to encode secreted enzymes. Ten CaEs were identified as being potentially catalytically competent. Transcript expression of acetylcholinesterase (ace1b) was significantly increased in multi-resistant lice compared to drug-susceptible L. salmonis, with transcript abundance further increased in preadult-II females following EMB exposure. In summary, results from the present study demonstrate that L. salmonis possesses fewer CaE gene family members than most arthropods characterized so far. Drug resistance in L. salmonis was associated with overexpression of ace1b.

A broadly active fucosyltransferase LmjFUT1 whose mitochondrial localization and activity are essential in parasitic Leishmania

Glycoconjugates play major roles in the infectious cycle of the trypanosomatid parasite Leishmania While GDP-Fucose synthesis is essential, fucosylated glycoconjugates have not been reported in Leishmania major [H. Guo et al., J. Biol. Chem. 292, 10696-10708 (2017)]. Four predicted fucosyltransferases appear conventionally targeted to the secretory pathway; SCA1/2 play a role in side-chain modifications of lipophosphoglycan, while gene deletion studies here showed that FUT2 and SCAL were not essential. Unlike most eukaryotic glycosyltransferases, the predicted α 1-2 fucosyltransferase encoded by FUT1 localized to the mitochondrion. A quantitative "plasmid segregation" assay, expressing FUT1 from the multicopy episomal pXNG vector in a chromosomal null ∆fut1- background, established that FUT1 is essential. Similarly, "plasmid shuffling" confirmed that both enzymatic activity and mitochondrial localization were required for viability, comparing import-blocked or catalytically inactive enzymes, respectively. Enzymatic assays of tagged proteins expressed in vivo or of purified recombinant FUT1 showed it had a broad fucosyltransferase activity including glycan and peptide substrates. Unexpectedly, a single rare ∆fut1- segregant (∆fut1s ) was obtained in rich media, which showed severe growth defects accompanied by mitochondrial dysfunction and loss, all of which were restored upon FUT1 reexpression. Thus, FUT1 along with the similar Trypanosoma brucei enzyme TbFUT1 [G. Bandini et al., bioRxiv, https://www.biorxiv.org/content/10.1101/726117v2 (2021)] joins the eukaryotic O-GlcNAc transferase isoform as one of the few glycosyltransferases acting within the mitochondrion. Trypanosomatid mitochondrial FUT1s may offer a facile system for probing mitochondrial glycosylation in a simple setting, and their essentiality for normal growth and mitochondrial function renders it an attractive target for chemotherapy of these serious human pathogens.

Poly ADP-ribose polymerase-1 promotes seed-setting rate by facilitating gametophyte development and meiosis in rice (Oryza sativa L.)

Poly(ADP-ribose) polymerases (PARPs), which transfer either monomer or polymer of ADP-ribose from nicotinamide adenine dinucleotide (NAD⁺ ) onto target proteins, are required for multiple processes in DNA damage repair, cell cycle, development, and abiotic stress in animals and plants. Here, the uncharacterized rice (Oryza sativa) OsPARP1, which has been predicted to have two alternative OsPARP1 mRNA splicing variants, OsPARP1.1 and OsPARP1.2, was investigated. However, bimolecular fluorescence complementation showed that only OsPARP1.1 interacted with OsPARP3 paralog, suggesting that OsPARP1.1 is a functional protein in rice. OsPARP1 was preferentially expressed in the stamen primordial and pollen grain of mature stamen during flower development. The osparp1 mutant and CRISPR plants were delayed in germination, indicating that defective DNA repair machinery impairs early seed germination. The mutant displayed a normal phenotype during vegetative growth but had a lower seed-setting rate than wild-type plants under normal conditions. Chromosome bridges and DNA fragmentations were detected in male meiocytes at anaphase I to prophase II. After meiosis II, malformed tetrads or tetrads with micronuclei were formed. Meanwhile, the abnormality was also found in embryo sac development. Collectively, these results suggest that OsPARP1 plays an important role in mediating response to DNA damage and gametophyte development, crucial for rice yield in the natural environment.

Mitochondrial ATP synthase subunit d, a component of the peripheral stalk, is essential for growth and heat stress tolerance in Arabidopsis thaliana

As rapid changes in climate threaten global crop yields, an understanding of plant heat stress tolerance is increasingly relevant. Heat stress tolerance involves the coordinated action of many cellular processes and is particularly energy demanding. We acquired a knockout mutant and generated knockdown lines in Arabidopsis thaliana of the d subunit of mitochondrial ATP synthase (gene name: ATPQ, AT3G52300, referred to hereafter as ATPd), a subunit of the peripheral stalk, and used these to investigate the phenotypic significance of this subunit in normal growth and heat stress tolerance. Homozygous knockout mutants for ATPd could not be obtained due to gametophytic defects, while heterozygotes possess no visible phenotype. Therefore, we used RNA interference to create knockdown plant lines for further studies. Proteomic analysis and blue native gels revealed that ATPd downregulation impairs only subunits of the mitochondrial ATP synthase (complex V). Knockdown plants were more sensitive to heat stress, had abnormal leaf morphology, and were severely slow growing compared to wild type. These results indicate that ATPd plays a crucial role in proper function of the mitochondrial ATP synthase holoenzyme, which, when reduced, leads to wide-ranging defects in energy-demanding cellular processes. In knockdown plants, more hydrogen peroxide accumulated and mitochondrial dysfunction stimulon (MDS) genes were activated. These data establish the essential structural role of ATPd and support the importance of complex V in normal plant growth, and provide new information about its requirement for heat stress tolerance.

Acylation of non-specific phospholipase C4 determines its function in plant response to phosphate deficiency

Non-specific phospholipase C (NPC) is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPCs mediate cellular functions, here we show that NPC4 is S-acylated at the C terminus and that acylation determines its plasma membrane (PM) association and function. The acylation of NPC4 was detected using NPC4 isolated from Arabidopsis and reconstituted in vitro. The C-terminal Cys-533 was identified as the S-acylation residue, and the mutation of Cys-533 to Ala-533 in NPC4 (NPC4^C533A ) led to the loss of S-acylation and membrane association of NPC4. The knockout of NPC4 impeded the phosphate deficiency-induced decrease of the phosphosphingolipid glycosyl inositol phosphoryl ceramide (GIPC), but introducing NPC4^C533A to npc4-1 failed to complement this defect, thereby supporting the hypothesis that the non-acylated NPC4^C533A fails to hydrolyze GIPC during phosphate deprivation. Moreover, NPC4^C533A failed to complement the primary root growth in npc4-1 under stress. In addition, NPC4 in Brassica napus was S-acylated and mutation of the S-acylating cysteine residue of BnaC01.NPC4 led to the loss of S-acylation and its membrane association. Together, our results reveal that S-acylation of NPC4 in the C terminus is conserved and required for its membrane association, phosphosphingolipid hydrolysis and function in plant stress responses.

Enzymatic characterization of ancestral/group-IV clade xyloglucan endotransglycosylase/hydrolase enzymes reveals broad substrate specificities

Xyloglucan endotransglycosylase/hydrolase (XTH) enzymes play important roles in cell wall remodelling. Although previous studies have shown a pathway of evolution for XTH genes from bacterial licheninases, through plant endoglucanases (EG16), the order of development within the phylogenetic clades of true XTHs is yet to be elucidated. In addition, recent studies have revealed interesting and potentially useful patterns of transglycosylation beyond the standard xyloglucan-xyloglucan donor/acceptor substrate activities. To study evolutionary relationships and to search for enzymes with useful broad substrate specificities, genes from the 'ancestral' XTH clade of two monocots, Brachypodium distachyon and Triticum aestivum, and two eudicots, Arabidopsis thaliana and Populus tremula, were investigated. Specific activities of the heterologously produced enzymes showed remarkably broad substrate specificities. All the enzymes studied had high activity with the cellulose analogue HEC (hydroxyethyl cellulose) as well as with mixed-link β-glucan as donor substrates, when compared with the standard xyloglucan. Even more surprising was the wide range of acceptor substrates that these enzymes were able to catalyse reactions with, opening a broad range of possible roles for these enzymes, both within plants and in industrial, pharmaceutical and medical fields. Genome screening and expression analyses unexpectedly revealed that genes from this clade were found only in angiosperm genomes and were predominantly or solely expressed in reproductive tissues. We therefore posit that this phylogenetic group is significantly different and should be renamed as the group-IV clade.

ACE2 Expression Is Upregulated in Inflammatory Corneal Epithelial Cells and Attenuated by Resveratrol

Purpose

The ocular surface is considered an important route for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. The expression level of the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is vital for viral infection. However, the regulation of ACE2 expression on the ocular surface is still unknown. We aimed to determine the change in ACE2 expression in inflamed corneal epithelium and explore potential drugs to reduce the expression of ACE2 on the ocular surface.

Methods

The expression of the SARS-CoV-2 receptors ACE2 and TMPRSS2 in human corneal epithelial cells (HCECs) was examined by qPCR and Western blotting. The altered expression of ACE2 in inflammatory corneal epithelium was evaluated in TNFα- and IL-1β-stimulated HCECs and inflamed mouse corneal epithelium, and the effect of resveratrol on ACE2 expression in HCECs was detected by immunofluorescence and Western blot analysis.

Results

ACE2 and TMPRSS2 are expressed on the human corneal epithelial cells. ACE2 expression is upregulated in HCECs by stimulation with TNFα and IL-1β and inflamed mouse corneas, including dry eye and alkali-burned corneas. In addition, resveratrol attenuates the increased expression of ACE2 induced by TNFα in HCECs.

Conclusions

This study demonstrates that ACE2 is highly expressed in HCECs and can be upregulated by stimulation with inflammatory cytokines and inflamed mouse corneal epithelium. Resveratrol may be able to reduce the increased expression of ACE2 on the inflammatory ocular surface. Our work suggests that patients with an inflammatory ocular surface may display higher ACE2 expression, which increases the risk of SARS-CoV-2 infection.

Apple MPK4 mediates phosphorylation of MYB1 to enhance light-induced anthocyanin accumulation

Anthocyanins are plant pigments with diverse biological functions that contribute to fruit quality and are beneficial to human health. Anthocyanin accumulation can be influenced by environmental signals, such as light, and plants have developed sophisticated systems to receive and transduce these signals. However, the associated molecular mechanisms are not well understood. In this study, we investigated the potential function of mitogen-activated protein kinases, which are members of the light signaling pathway, during light-induced anthocyanin accumulation in apple (Malus domestica) fruit peels. An antibody array and yeast two-hybrid screen indicated that proteins encoded by two MdMPK4 genes are light-activated and interact with the transcription factor and anthocyanin biosynthesis regulator MdMYB1. A phosphorylation assay showed that the MdMPK4 proteins phosphorylate MdMYB1, thereby increasing its stability under light conditions. Transient MdMPK4 and MdMYB1 overexpression assays further revealed that light-induced anthocyanin accumulation relies on MdMPK4 kinase activity, which is required for maximum MdMYB1 activity. Based on the expression of the chromosome 6 allele MdMPK4-06G under light conditions and the presence of light response elements in the MdMPK4-06G promoter, we concluded that it is more responsive to light than the chromosome 14 allele MdMPK4-14G. These results suggest a potential biotechnological strategy for increasing fruit anthocyanin content via light induction.

A β-lactamase gene of Fusarium oxysporum alters the rhizosphere microbiota of soybean

The rhizosphere is a multitrophic environment, and for soilborne pathogens such as Fusarium oxysporum, microbial competition in the rhizosphere is inevitable before reaching and infecting roots. This study established a tritrophic interaction among the plant growth-promoting rhizobacterium Burkholderia ambifaria, F. oxysporum and Glycine max (soybean) to study the effects of F. oxysporum genes on shaping the soybean microbiota. Although B. ambifaria inhibited mycelial growth and increased bacterial propagation in the presence of F. oxysporum, F. oxysporum still managed to infect soybean in the presence of B. ambifaria. RNA-Seq identified a putative F. oxysporum secretory β-lactamase-coding gene, FOXG_18438 (abbreviated as Fo18438), that is upregulated during soybean infection in the presence of B. ambifaria. The ∆Fo18438 mutants displayed reduced mycelial growth towards B. ambifaria, and the complementation of full Fo18438 and the Fo18438 β-lactamase domain restored mycelial growth. Using the F. oxysporum wild type, ∆Fo18438 mutants and complemented strains with full Fo18438, Fo18438 β-lactamase domain or Fo18438 RTA1-like domain for soil inoculation, 16S rRNA amplicon sequencing revealed that the abundance of a Burkholderia operational taxonomic unit (OTU) was increased in the rhizosphere microbiota infested by the strains with Fo18438 β-lactamase domain. Non-metric multidimensional scaling and PICRUSt2 functional analysis revealed differential abundance for the bacterial β-lactam-related functions when contrasting the genotypes of F. oxysporum. These results indicated that the Fo18438 β-lactamase domain provides F. oxysporum with the advantage of growing into the soybean rhizosphere, where β-lactam antibiosis is involved in microbial competition. Accordingly, this study highlights the capability of an F. oxysporum gene for altering the soybean rhizosphere and taproot microbiota.

Interspecies Behavioral Variability of Medaka Fish Assessed by Comparative Phenomics

Recently, medaka has been used as a model organism in various research fields. However, even though it possesses several advantages over zebrafish, fewer studies were done in medaka compared to zebrafish, especially with regard to its behavior. Thus, to provide more information regarding its behavior and to demonstrate the behavioral differences between several species of medaka, we compared the behavioral performance and biomarker expression in the brain between four medaka fishes, Oryzias latipes, Oryzias dancena, Oryzias woworae, and Oryzias sinensis. We found that each medaka species explicitly exhibited different behaviors to each other, which might be related to the different basal levels of several biomarkers. Furthermore, by phenomics and genomic-based clustering, the differences between these medaka fishes were further investigated. Here, the phenomic-based clustering was based on the behavior results, while the genomic-based clustering was based on the sequence of the nd2 gene. As we expected, both clusterings showed some resemblances to each other in terms of the interspecies relationship between medaka and zebrafish. However, this similarity was not displayed by both clusterings in the medaka interspecies comparisons. Therefore, these results suggest a re-interpretation of several prior studies in comparative biology. We hope that these results contribute to the growing database of medaka fish phenotypes and provide one of the foundations for future phenomics studies of medaka fish.

MYCN-Amplified Neuroblastoma Is Addicted to Iron and Vulnerable to Inhibition of the System Xc-/Glutathione Axis

MYCN is amplified in 20% to 25% of neuroblastoma, and MYCN-amplified neuroblastoma contributes to a large percent of pediatric cancer-related deaths. Therapy improvements for this subtype of cancer are a high priority. Here we uncover a MYCN-dependent therapeutic vulnerability in neuroblastoma. Namely, amplified MYCN rewires the cell through expression of key receptors, ultimately enhancing iron influx through increased expression of the iron import transferrin receptor 1. Accumulating iron causes reactive oxygen species (ROS) production, and MYCN-amplified neuroblastomas show enhanced reliance on the system Xc- cystine/glutamate antiporter for ROS detoxification through increased transcription of this receptor. This dependence creates a marked vulnerability to targeting the system Xc-/glutathione (GSH) pathway with ferroptosis inducers. This reliance can be exploited through therapy with FDA-approved rheumatoid arthritis drugs sulfasalazine (SAS) and auranofin: in MYCN-amplified, patient-derived xenograft models, both therapies blocked growth and induced ferroptosis. SAS and auranofin activity was largely mitigated by the ferroptosis inhibitor ferrostatin-1, antioxidants like N-acetyl-L-cysteine, or by the iron scavenger deferoxamine (DFO). DFO reduced auranofin-induced ROS, further linking increased iron capture in MYCN-amplified neuroblastoma to a therapeutic vulnerability to ROS-inducing drugs. These data uncover an oncogene vulnerability to ferroptosis caused by increased iron accumulation and subsequent reliance on the system Xc-/GSH pathway. SIGNIFICANCE: This study shows how MYCN increases intracellular iron levels and subsequent GSH pathway activity and demonstrates the antitumor activity of FDA-approved SAS and auranofin in patient-derived xenograft models of MYCN-amplified neuroblastoma.

The KMT2A gene: mRNA differential expression in the ovary and a novel 13-nt nucleotide sequence variant associated with litter size in cashmere goats

A genome-wide association study had shown that lysine methyltransferase 2A (KMT2A), which encodes the histone 3 lysine 4 methyltransferase and reportedly can regulate gametogenesis, steroidogenesis, and development as well as other biological processes, is a potential candidate gene influencing litter size in the dairy goat, suggesting its key function in animal reproduction. Here, we aimed to explore the genetic effects of the KMT2A gene on litter size in females of the Chinese indigenous cashmere goat, using a large sample size (n > 1,000), based on their levels of RNA transcription and DNA variation. First, mRNA expression levels of this gene in ovarian tissues between the low-prolific group (first-born litter size = 1) and high-prolific group (first-born litter size ≥2) were significantly different, revealing the potential functioning of KMT2A in goat prolific. Moreover, a novel 13-nt nucleotide sequence variant was identified in Shaanbei white cashmere goats (n = 1,616). In accordance with the independent chi-square (χ²) analysis, the distribution of genotypes (P = 2.57 × 10^-9) and allelotypes (P = 3.00 × 10^-7) between the low- and high-prolific groups differed significantly, indicating the 13-nt mutation was associated with litter size. Further analysis showed that the insertion/insertion (II) genotype was significantly different with insertion/deletion (ID) (P = 1.76 × 10^-9) and deletion/deletion (DD) (P = 7.00 × 10^-6), with goats having the DD genotype producing an average litter size larger than the other genotypes. Taken together, these findings suggest KMT2A can serve as a candidate gene for breeding goats, which may have implications for improving the future development of the goat industry.

The Arabidopsis V-ATPase is localized to the TGN/EE via a seed plant-specific motif

The V-ATPase is a versatile proton-pump found in a range of endomembrane compartments yet the mechanisms governing its differential targeting remain to be determined. In Arabidopsis, VHA-a1 targets the V-ATPase to the TGN/EE whereas VHA-a2 and VHA-a3 are localized to the tonoplast. We report here that the VHA-a1 targeting domain serves as both an ER-exit and as a TGN/EE-retention motif and is conserved among seed plants. In contrast, Marchantia encodes a single VHA-isoform that localizes to the TGN/EE and the tonoplast in Arabidopsis. Analysis of CRISPR/Cas9 generated null alleles revealed that VHA-a1 has an essential function for male gametophyte development but acts redundantly with the tonoplast isoforms during vegetative growth. We propose that in the absence of VHA-a1, VHA-a3 is partially re-routed to the TGN/EE. Our findings contribute to understanding the evolutionary origin of V-ATPase targeting and provide a striking example that differential localization does not preclude functional redundancy.

β-Cell-Specific Deletion of HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) Reductase Causes Overt Diabetes due to Reduction of β-Cell Mass and Impaired Insulin Secretion

Inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), statins, which are used to prevent cardiovascular diseases, are associated with a modest increase in the risk of new-onset diabetes. To investigate the role of HMGCR in the development of β-cells and glucose homeostasis, we deleted Hmgcr in a β-cell-specific manner by using the Cre-loxP technique. Mice lacking Hmgcr in β-cells (β-KO) exhibited hypoinsulinemic hyperglycemia as early as postnatal day 9 (P9) due to decreases in both β-cell mass and insulin secretion. Ki67-positive cells were reduced in β-KO mice at P9; thus, β-cell mass reduction was caused by proliferation disorder immediately after birth. The mRNA expression of neurogenin3 (Ngn3), which is transiently expressed in endocrine progenitors of the embryonic pancreas, was maintained despite a striking reduction in the expression of β-cell-associated genes, such as insulin, pancreatic and duodenal homeobox 1 (Pdx1), and MAF BZIP transcription factor A (Mafa) in the islets from β-KO mice. Histological analyses revealed dysmorphic islets with markedly reduced numbers of β-cells, some of which were also positive for glucagon. In conclusion, HMGCR plays critical roles not only in insulin secretion but also in the development of β-cells in mice.

Identification and characterization of two isoforms of acyl-coenzyme A oxidase 1 gene and their expression in fasting-induced grass carp Ctenopharyngodon idella adipocyte lipolysis

Acyl-coenzyme A oxidases 1 (ACOX1) is the first rate-limiting enzyme responsible for peroxisomal β-oxidation. In the present study, two mRNA variants, ACOX1a and ACOX1b, transcribed from a single gene, were for the first time isolated and characterized from grass carp Ctenopharyngodon idella, both encoding putative peptides of 660 amino acids. Analysis of the exon-intron structures clarified that grass carp ACOX1a and ACOX1b comprise 14 coding exons and correspond to 3a and 3b isoforms of exon 3 splicing variants. Both ACOX1a and ACOX1b mRNAs were expressed in a wide range of tissues, but the abundance of each ACOX1 mRNA showed the tissue-dependent expression patterns. Time-course analysis of ACOX1 expressions indicated that the level of ACOX1a mRNA reached an almost maximal level at day 2, while that of ACOX1b mRNA reached an almost maximal level at day 8 during grass carp primary preadipocyte differentiation. In fasting-induced adipocyte lipolysis, only ACOX1a showed a significant increase in adipocyte, indicating that two ACOX1 isoforms may serve somewhat different roles in the peroxisomal β-oxidation. These results suggested that grass carp ACOX1a and ACOX1b were differently modulated by fasting in adipocyte. In addition, we found that mitochondrial β-oxidation might dominate at the early stage of fasting in adipocytes, indicating that mitochondria and peroxisomes might possess different capacities in fasting-induced adipocytes fatty acid oxidation.

Cloning and functional complementation of ten Schistosoma mansoni phosphodiesterases expressed in the mammalian host stages

Only a single drug against schistosomiasis is currently available and new drug development is urgently required but very few drug targets have been validated and characterised. However, regulatory systems including cyclic nucleotide metabolism are emerging as primary candidates for drug discovery. Here, we report the cloning of ten cyclic nucleotide phosphodiesterase (PDE) genes of S. mansoni, out of a total of 11 identified in its genome. We classify these PDEs by homology to human PDEs. Male worms displayed higher expression levels for all PDEs, in mature and juvenile worms, and schistosomula. Several functional complementation approaches were used to characterise these genes. We constructed a Trypanosoma brucei cell line in which expression of a cAMP-degrading PDE complements the deletion of TbrPDEB1/B2. Inhibitor screens of these cells expressing only either SmPDE4A, TbrPDEB1 or TbrPDEB2, identified highly potent inhibitors of the S. mansoni enzyme that elevated the cellular cAMP concentration. We further expressed most of the cloned SmPDEs in two pde1Δ/pde2Δ strains of Saccharomyces cerevisiae and some also in a specialised strain of Schizosacharomyces pombe. Five PDEs, SmPDE1, SmPDE4A, SmPDE8, SmPDE9A and SmPDE11 successfully complemented the S. cerevisiae strains, and SmPDE7var also complemented to a lesser degree, in liquid culture. SmPDE4A, SmPDE8 and SmPDE11 were further assessed in S. pombe for hydrolysis of cAMP and cGMP; SmPDE11 displayed considerable preferrence for cGMP over cAMP. These results and tools enable the pursuit of a rigorous drug discovery program based on inhibitors of S. mansoni PDEs.

Myo-inositol Oxygenase (MIOX) Overexpression Drives the Progression of Renal Tubulointerstitial Injury in Diabetes

Conceivably, upregulation of myo-inositol oxygenase (MIOX) is associated with altered cellular redox. Its promoter includes oxidant-response elements, and we also discovered binding sites for XBP1, a transcription factor of endoplasmic reticulum (ER) stress response. Previous studies indicate that MIOX's upregulation in acute tubular injury is mediated by oxidant and ER stress. Here, we investigated whether hyperglycemia leads to accentuation of oxidant and ER stress while these boost each other's activities, thereby augmenting tubulointerstitial injury/fibrosis. We generated MIOX-overexpressing transgenic (MIOX-TG) and MIOX knockout (MIOX-KO) mice. A diabetic state was induced by streptozotocin administration. Also, MIOX-KO were crossbred with Ins2 ^Akita to generate Ins2 ^Akita/KO mice. MIOX-TG mice had worsening renal functions with kidneys having increased oxidant/ER stress, as reflected by DCF/dihydroethidium staining, perturbed NAD-to-NADH and glutathione-to-glutathione disulfide ratios, increased NOX4 expression, apoptosis and its executionary molecules, accentuation of TGF-β signaling, Smads and XBP1 nuclear translocation, expression of GRP78 and XBP1 (ER stress markers), and accelerated tubulointerstitial fibrosis. These changes were not seen in MIOX-KO mice. Interestingly, such changes were remarkably reduced in Ins2 ^Akita/KO mice and, likewise, in vitro experiments with XBP1 siRNA. These findings suggest that MIOX expression accentuates, while its deficiency shields kidneys from, tubulointerstitial injury by dampening oxidant and ER stress, which mutually enhance each other's activity.

The defective effect of starch branching enzyme IIb from weak to strong induces the formation of biphasic starch granules in amylose-extender maize endosperm

Biphasic starch granules in maize ae mutant underwent the weak to strong SBEIIb-defective effect during endosperm development, leading to no birefringence in their exterior due to extended long branch-chains of amylopectin. Biphasic starch granules are usually detected regionally in cereal endosperm lacking starch branching enzyme (SBE). However, their molecular structure, formation mechanism, and regional distribution are unclear. In this research, biphasic starch granules were observed in the inner region of crown endosperm of maize ae mutant, and had poorly oriented structure with comb-like profiles in their exterior. The inner endosperm (IE) rich in biphasic starch granules and outer endosperm (OE) without biphasic starch granules were investigated. The starch had lower amylose content and higher proportion of long branch-chains of amylopectin in IE than in OE, and the exterior of biphasic starch granules had less amylose and more long branch-chains of amylopectin than the interior. Compared with OE, the expression pattern of starch synthesis related enzymes changed significantly in IE. The granule-bound starch synthase I activity within biphasic starch granules decreased slightly. The IE experienced more severe hypoxic stress than OE, and the up-regulated anaerobic respiration pathway indicated an increase in carbon consumption. The starch in IE underwent the SBEIIb-defective effect from weak to strong due to the lack of sufficient carbon inflow, leading to the formation of biphasic starch granules and their regional distribution in endosperm. The results provided information for understanding the biphasic starch granules.

Adipose Triglyceride Lipase Is a Key Lipase for the Mobilization of Lipid Droplets in Human β-Cells and Critical for the Maintenance of Syntaxin 1a Levels in β-Cells

Lipid droplets (LDs) are frequently increased when excessive lipid accumulation leads to cellular dysfunction. Distinct from mouse β-cells, LDs are prominent in human β-cells. However, the regulation of LD mobilization (lipolysis) in human β-cells remains unclear. We found that glucose increases lipolysis in nondiabetic human islets but not in islets in patients with type 2 diabetes (T2D), indicating dysregulation of lipolysis in T2D islets. Silencing adipose triglyceride lipase (ATGL) in human pseudoislets with shRNA targeting ATGL (shATGL) increased triglycerides (TGs) and the number and size of LDs, indicating that ATGL is the principal lipase in human β-cells. In shATGL pseudoislets, biphasic glucose-stimulated insulin secretion (GSIS), and insulin secretion to 3-isobutyl-1-methylxanthine and KCl were all reduced without altering oxygen consumption rate compared with scramble control. Like human islets, INS1 cells showed visible LDs, glucose-responsive lipolysis, and impairment of GSIS after ATGL silencing. ATGL-deficient INS1 cells and human pseudoislets showed reduced SNARE protein syntaxin 1a (STX1A), a key SNARE component. Proteasomal degradation of Stx1a was accelerated likely through reduced palmitoylation in ATGL-deficient INS1 cells. Therefore, ATGL is responsible for LD mobilization in human β-cells and supports insulin secretion by stabilizing STX1A. The dysregulated lipolysis may contribute to LD accumulation and β-cell dysfunction in T2D islets.

Hyperuricemia Predisposes to the Onset of Diabetes via Promoting Pancreatic β-Cell Death in Uricase-Deficient Male Mice

Clinical studies have shown a link between hyperuricemia (HU) and diabetes, while the exact effect of soluble serum urate on glucose metabolism remains elusive. This study aims to characterize the glucose metabolic phenotypes and investigate the underlying molecular mechanisms using a novel spontaneous HU mouse model in which the uricase (Uox) gene is absent. In an attempt to study the role of HU in glycometabolism, we implemented external stimulation on Uox knockout (KO) and wild-type (WT) males with a high-fat diet (HFD) and/or injections of multiple low-dose streptozotocin (MLD-STZ) to provoke the potential role of urate. Notably, while Uox-KO mice developed glucose intolerance in the basal condition, no mice spontaneously developed diabetes, even with aging. HFD-fed Uox-KO mice manifested similar insulin sensitivity compared with WT controls. HU augmented the existing glycometabolism abnormality induced by MLD-STZ and eventually led to diabetes, as evidenced by the increased random glucose. Reduced β-cell masses and increased terminal deoxynucleotidyl TUNEL-positive β-cells suggested that HU-mediated diabetes was cell death dependent. However, urate-lowering therapy (ULT) cannot ameliorate the diabetes incidence or reverse β-cell apoptosis with significance. ULT displayed a significant therapeutic effect of HU-crystal-associated kidney injury and tubulointerstitial damage in diabetes. Moreover, we present transcriptomic analysis of isolated islets, using Uox-KO versus WT mice and streptozotocin-induced diabetic WT (STZ-WT) versus diabetic Uox-KO (STZ-KO) mice. Shared differentially expressed genes of HU primacy revealed Stk17β is a possible target gene in HU-related β-cell death. Together, this study suggests that HU accelerates but does not cause diabetes by inhibiting islet β-cell survival.

Statins Suppress TGF-β2-Mediated MMP-2 and MMP-9 Expression and Activation Through RhoA/ROCK Inhibition in Astrocytes of the Human Optic Nerve Head

Purpose

Matrix metalloproteinases (MMPs) are involved in extracellular matrix (ECM) maintenance and remodeling. The present study aimed to determine whether transforming growth factor (TGF)-β2 regulates MMP-2 and MMP-9 levels and activities in astrocytes derived from the optic nerve head (ONH) and the role of statins in such modulation.

Methods

Primary astrocytes cultured from the lamina cribrosa of human donor ONHs were incubated with three types of statins (5 µg/mL) for 1 hour followed by recombinant TGF-β2 (5 ng/mL) for various periods to test their effects. Levels and activities of MMP-2 and MMP-9 in astrocytes in vitro were determined by western blotting and zymography, respectively. Levels of phosphorylated myosin phosphatase target subunit 1 (MYPT1) in astrocyte lysates were determined by western blotting, and those of phosphorylated myosin light chain (MLC) were determined by western blotting and immunocytochemistry.

Results

MMP-2 and MMP-9 levels were upregulated by TGF-β2 in human ONH astrocytes. Prior incubation with simvastatin, lovastatin, and atorvastatin inhibited TGF-β2-mediated MMP-2 and MMP-9 expression and activities. Prior incubation with statins downregulated the TGF-β2-induced phosphorylation of MYPT1 and MLC, which are downstream substrates of RhoA and ROCKs.

Conclusions

Statins inhibited the TGF-β2-mediated regulation of MMP-2 and MMP-9 by inhibiting the RhoA/ROCK signaling pathway. Considering the role of MMP in ECM remodeling, the present findings support the notion that statins positively impact ECM remodeling within the ONH.

Inorganic Nitrate Promotes Glucose Uptake and Oxidative Catabolism in White Adipose Tissue Through the XOR-Catalyzed Nitric Oxide Pathway

An aging global population combined with sedentary lifestyles and unhealthy diets has contributed to an increasing incidence of obesity and type 2 diabetes. These metabolic disorders are associated with perturbations to nitric oxide (NO) signaling and impaired glucose metabolism. Dietary inorganic nitrate, found in high concentration in green leafy vegetables, can be converted to NO in vivo and demonstrates antidiabetic and antiobesity properties in rodents. Alongside tissues including skeletal muscle and liver, white adipose tissue is also an important physiological site of glucose disposal. However, the distinct molecular mechanisms governing the effect of nitrate on adipose tissue glucose metabolism and the contribution of this tissue to the glucose-tolerant phenotype remain to be determined. Using a metabolomic and stable-isotope labeling approach, combined with transcriptional analysis, we found that nitrate increases glucose uptake and oxidative catabolism in primary adipocytes and white adipose tissue of nitrate-treated rats. Mechanistically, we determined that nitrate induces these phenotypic changes in primary adipocytes through the xanthine oxidoreductase-catalyzed reduction of nitrate to NO and independently of peroxisome proliferator-activated receptor-α. The nitrate-mediated enhancement of glucose uptake and catabolism in white adipose tissue may be a key contributor to the antidiabetic effects of this anion.

Unbiased proteomics identifies plasminogen activator inhibitor-1 as a negative regulator of endothelial nitric oxide synthase

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is a critical mediator of vascular function. eNOS is tightly regulated at various levels, including transcription, co- and posttranslational modifications, and by various protein-protein interactions. Using stable isotope labeling with amino acids in cell culture (SILAC) and mass spectrometry (MS), we identified several eNOS interactors, including the protein plasminogen activator inhibitor-1 (PAI-1). In cultured human umbilical vein endothelial cells (HUVECs), PAI-1 and eNOS colocalize and proximity ligation assays demonstrate a protein-protein interaction between PAI-1 and eNOS. Knockdown of PAI-1 or eNOS eliminates the proximity ligation assay (PLA) signal in endothelial cells. Overexpression of eNOS and HA-tagged PAI-1 in COS7 cells confirmed the colocalization observations in HUVECs. Furthermore, the source of intracellular PAI-1 interacting with eNOS was shown to be endocytosis derived. The interaction between PAI-1 and eNOS is a direct interaction as supported in experiments with purified proteins. Moreover, PAI-1 directly inhibits eNOS activity, reducing NO synthesis, and the knockdown or antagonism of PAI-1 increases NO bioavailability. Taken together, these findings place PAI-1 as a negative regulator of eNOS and disruptions in eNOS-PAI-1 binding promote increases in NO production and enhance vasodilation in vivo.

Goat DNMT3B: An indel mutation detection, association analysis with litter size and mRNA expression in gonads

DNA methyltransferase 3β (DNMT3B) is a gene encoding a de novo methylation enzyme that is required for DNA methylation during mammalian embryo development. Previous genome-wide association analysis suggested DNMT3B is a candidate gene for goat fertility, but there is no study on the effect of DNMT3B on litter size in goat. The aim of this study was to identify possible insertion/deletion (indel) mutations associated with litter size. Seven putative indels were designed to study their association with litter size, but just one 11-bp insertion variant of intron 22 (the last intron) was found in healthy female Shaanbei white cashmere goats (SBWC goats) (n = 1534). Statistical analysis showed that the 11-bp insertion was related to the first-born litter size (P < 0.01) and the goats with the deletion/deletion genotype had a higher average first-born litter size (P < 0.01). In addition, the expression profile of the DNMT3B mRNA in goat was detected, which revealed significant differences in DNMT3B mRNA expression in the gonads. Additionally, the results of western blotting revealed that the ovaries of mothers of multi-lamb (MML) had a higher level of DNMT3B protein than the ovaries of mothers of single-lamb (MSL). Furthermore, the mRNA of DNMT3B was widely expressed in male goats. Differences in mRNA expression levels were observed in the ovaries of MSL and MML. These findings indicated that the 11-bp indel in DNMT3B was significantly associated with first-born litter size, which can be used for marker-assisted selection (MAS) of goats for breeding.

Molecular basis for catabolism of the abundant metabolite trans-4-hydroxy-L-proline by a microbial glycyl radical enzyme

The glycyl radical enzyme (GRE) superfamily utilizes a glycyl radical cofactor to catalyze difficult chemical reactions in a variety of anaerobic microbial metabolic pathways. Recently, a GRE, trans-4-hydroxy-L-proline (Hyp) dehydratase (HypD), was discovered that catalyzes the dehydration of Hyp to (S)-Δ1-pyrroline-5-carboxylic acid (P5C). This enzyme is abundant in the human gut microbiome and also present in prominent bacterial pathogens. However, we lack an understanding of how HypD performs its unusual chemistry. Here, we have solved the crystal structure of HypD from the pathogen Clostridioides difficile with Hyp bound in the active site. Biochemical studies have led to the identification of key catalytic residues and have provided insight into the radical mechanism of Hyp dehydration.

Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity

Cytochrome c oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome c affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p₅₀ (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.

New Delhi Metallo-β-Lactamase 5-Producing Klebsiella pneumoniae Sequence Type 258, Southwest China, 2017

We isolated a New Delhi metallo-β-lactamase 5 (NDM-5)–producing Klebsiella pneumoniae sequence type (ST) 258 strain in southwest China during 2017. The bla_NDM-5 gene was acquired by horizontal plasmid transfer from NDM-5–producing Escherichia coli. We identified genomic characteristics in ST258 strains that differed from those of global K. pneumoniae carbapenemase–producing strains.

Transcriptome Profiling Unravels a Vital Role of Pectin and Pectinase in Anther Dehiscence in Chrysanthemum

Chrysanthemum (Chrysanthemum morifolium (Ramat.) Kitamura) plants have great ornamental value, but their flowers can also be a source of pollen contamination. Previously, morphological and cytological studies have shown that anthers of some chrysanthemum cultivars such as 'Qx-115' fail to dehisce, although the underlying mechanism is largely unknown. In this study, we investigated the molecular basis of anther indehiscence in chrysanthemum via transcriptome analysis of a dehiscent cultivar ('Qx-097') and an indehiscent cultivar ('Qx-115'). We also measured related physiological indicators during and preceding the period of anther dehiscence. Our results showed a difference in pectinase accumulation and activity between the two cultivars during dehiscence. Detection of de-esterified pectin and highly esterified pectin in anthers during the period preceding anther dehiscence using LM19 and LM20 monoclonal antibodies showed that both forms of pectin were absent in the stomium region of 'Qx-097' anthers but were abundant in that of 'Qx-115' anthers. Analysis of transcriptome data revealed a significant difference in the expression levels of two transcription factor-encoding genes, CmLOB27 and CmERF72, between 'Qx-097' and 'Qx-115' during anther development. Transient overexpression of CmLOB27 and CmERF72 separately in tobacco leaves promoted pectinase biosynthesis. We conclude that CmLOB27 and CmERF72 are involved in the synthesis of pectinase, which promotes the degradation of pectin. Our results lay a foundation for further investigation of the role of CmLOB27 and CmERF72 transcription factors in the process of anther dehiscence in chrysanthemum.

UGT709G1: a novel uridine diphosphate glycosyltransferase involved in the biosynthesis of picrocrocin, the precursor of safranal in saffron (Crocus sativus)

Saffron, a spice derived from the dried red stigmas of Crocus sativus, is one of the oldest natural food additives. The flowers have long red stigmas, which store significant quantities of the glycosylated apocarotenoids crocins and picrocrocin. The apocarotenoid biosynthetic pathway in saffron starts with the oxidative cleavage of zeaxanthin, from which crocins and picrocrocin are derived. In the processed stigmas, picrocrocin is converted to safranal, giving saffron its typical aroma. By a targeted search for differentially expressed uridine diphosphate glycosyltransferases (UGTs) in Crocus transcriptomes, a novel apocarotenoid glucosyltransferase (UGT709G1) from saffron was identified. Biochemical analyses revealed that UGT709G1 showed a high catalytic efficiency toward 2,6,6-trimethyl-4-hydroxy-1-carboxaldehyde-1-cyclohexene (HTCC), making it suited for the biosynthesis of picrocrocin, the precursor of safranal. The role of UGT709G1 in picrocrocin/safranal biosynthesis was supported by the absence or presence of gene expression in a screening for HTCC and picrocrocin production in different Crocus species and by a combined transient expression assay with CsCCD2L in Nicotiana benthamiana leaves. The identification of UGT709G1 completes one of the most highly valued specialized metabolic biosynthetic pathways in plants and provides novel perspectives on the industrial production of picrocrocin to be used as a flavor additive or as a pharmacological constituent.

Increase in lysophosphatidate acyltransferase activity in oilseed rape (Brassica napus) increases seed triacylglycerol content despite its low intrinsic flux control coefficient

Lysophosphatidate acyltransferase (LPAAT) catalyses the second step of the Kennedy pathway for triacylglycerol (TAG) synthesis. In this study we expressed Trapaeolum majus LPAAT in Brassica napus (B. napus) cv 12075 to evaluate the effects on lipid synthesis and estimate the flux control coefficient for LPAAT. We estimated the flux control coefficient of LPAAT in a whole plant context by deriving a relationship between it and overall lipid accumulation, given that this process is a exponential. Increasing LPAAT activity resulted in greater TAG accumulation in seeds of between 25% and 29%; altered fatty acid distributions in seed lipids (particularly those of the Kennedy pathway); and a redistribution of label from 14 C-glycerol between phosphoglycerides. Greater LPAAT activity in seeds led to an increase in TAG content despite its low intrinsic flux control coefficient on account of the exponential nature of lipid accumulation that amplifies the effect of the small flux increment achieved by increasing its activity. We have also developed a novel application of metabolic control analysis likely to have broad application as it determines the in planta flux control that a single component has upon accumulation of storage products.

CRISPR/Cas9 knockout of leghemoglobin genes in Lotus japonicus uncovers their synergistic roles in symbiotic nitrogen fixation

Legume nodules contain high concentrations of leghemoglobins (Lbs) encoded by several genes. The reason for this multiplicity is unknown. CRISPR/Cas9 technology was used to generate stable mutants of the three Lbs of Lotus japonicus. The phenotypes were characterized at the physiological, biochemical and molecular levels. Nodules of the triple mutants were examined by electron microscopy and subjected to RNA-sequencing (RNA-seq) analysis. Complementation studies revealed that Lbs function synergistically to maintain optimal N₂ fixation. The nodules of the triple mutants overproduced superoxide radicals and hydrogen peroxide, which was probably linked to activation of NADPH oxidases and changes in superoxide dismutase isoforms expression. The mutant nodules showed major ultrastructural alterations, including vacuolization, accumulation of poly-β-hydroxybutyrate and disruption of mitochondria. RNA-seq of c. 20 000 genes revealed significant changes in expression of carbon and nitrogen metabolism genes, transcription factors, and proteinases. Lb-deficient nodules had c. 30-50-fold less heme but similar transcript levels of heme biosynthetic genes, suggesting a post-translational regulatory mechanism of heme synthesis. We conclude that Lbs act additively in nodules and that the lack of Lbs results in early nodule senescence. Our observations also provide insight into the reprogramming of the gene expression network associated with Lb deficiency, probably as a result of uncontrolled intracellular free O₂ concentration.

Properties and functions of calcium-dependent protein kinases and their relatives in Arabidopsis thaliana

Calcium is a ubiquitous second messenger that mediates plant responses to developmental and environmental cues. Calcium-dependent protein kinases (CDPKs) are key actors of plant signaling that convey calcium signals into physiological responses by phosphorylating various substrates including ion channels, transcription factors and metabolic enzymes. This large diversity of targets confers pivotal roles of CDPKs in shoot and root development, pollen tube growth, stomatal movements, hormonal signaling, transcriptional reprogramming and stress tolerance. On the one hand, specificity in CDPK signaling is achieved by differential calcium sensitivities, expression patterns, subcellular localizations and substrates. On the other hand, CDPKs also target some common substrates to ensure key cellular processes indispensable for plant growth and survival in adverse environmental conditions. In addition, the CDPK-related protein kinases (CRKs) might be closer to some CDPKs than previously anticipated and could contribute to calcium signaling despite their inability to bind calcium. This review highlights the regulatory properties of Arabidopsis CDPKs and CRKs that coordinate their multifaceted functions in development, immunity and abiotic stress responses.

Cardiac contractile dysfunction and protein kinase C-mediated myofilament phosphorylation in disease and aging

Increases in protein kinase C (PKC) are associated with diminished cardiac function, but the contribution of downstream myofilament phosphorylation is debated in human and animal models of heart failure. The current experiments evaluated PKC isoform expression, downstream cardiac troponin I (cTnI) S44 phosphorylation (p-S44), and contractile function in failing (F) human myocardium, and in rat models of cardiac dysfunction caused by pressure overload and aging. In F human myocardium, elevated PKCα expression and cTnI p-S44 developed before ventricular assist device implantation. Circulatory support partially reduced PKCα expression and cTnI p-S44 levels and improved cellular contractile function. Gene transfer of dominant negative PKCα (PKCαDN) into F human myocytes also improved contractile function and reduced cTnI p-S44. Heightened cTnI phosphorylation of the analogous residue accompanied reduced myocyte contractile function in a rat model of pressure overload and in aged Fischer 344 × Brown Norway F1 rats (≥26 mo). Together, these results indicate PKC-targeted cTnI p-S44 accompanies cardiac cellular dysfunction in human and animal models. Interfering with PKCα activity reduces downstream cTnI p-S44 levels and partially restores function, suggesting cTnI p-S44 may be a useful target to improve contractile function in the future.

[Effects of low temperature on trehalose and trehalase contents in Culex pipiens pallens]

OBJECTIVE

To examine the effect of low temperature on trehalose and trehalase levels in Culex pipiens pallens.

METHODS

The fourth instar larvae and female adult mosquitoes of Cx. pipiens pallens were exposed at 4 ℃ for 0, 1, 3, 6, 12, 18, 24 h and 0, 1, 3, 6, 12, 18, 24, 36, 48, 72 h, respectively. Then, the trehalose and trehalase contents were detected by enzyme-linked immunosorbent assay (ELISA) in mosquitoes.

RESULTS

The contents of trehalose and trehalase significantly increased in the larval and female adult mosquitoes post-exposure to low temperature. The changing trend of trehalose levels was consistent in the larval and female adult mosquitoes, and the highest levels were (2.458 8 ± 0.379 2) mg/g and (2.825 7 ± 0.211 1) mg/g 3 h post-exposure to low temperature, respectively. The trehalose and trehalase levels fluctuated greatly within the first 6 h post-exposure to low temperature. Following adaptation for a period of time, the trehalose and trehalase levels remained at a relatively high level.

CONCLUSIONS

Low temperature may induce the production of trehalose and trehalase in Cx. pipiens pallens, and the trehalose and trehalase may play an important role in the improvement of the cold resistance.

p116Rip promotes myosin phosphatase activity in airway smooth muscle cells

Myosin phosphatase-Rho interacting protein (p116^Rip ) was originally found as a RhoA-binding protein. Subsequent studies by us and others revealed that p116^Rip facilitates myosin light chain phosphatase (MLCP) activity through direct and indirect manners. However, it is unclear how p116^Rip regulates myosin phosphatase activity in cells. To elucidate the role of p116^Rip in cellular contractile processes, we suppressed the expression of p116^Rip by RNA interference in human airway smooth muscle cells (HASMCs). We found that knockdown of p116^Rip in HASMCs led to increased di-phosphorylated MLC (pMLC), that is phosphorylation at both Ser19 and Thr18. This was because of a change in the interaction between MLCP and myosin, but not an alteration of RhoA/ROCK signaling. Attenuation of Zipper-interacting protein kinase (ZIPK) abolished the increase in di-pMLC, suggesting that ZIPK is involved in this process. Moreover, suppression of p116^Rip expression in HASMCs substantially increased the histamine-induced collagen gel contraction. We also found that expression of the p116^Rip was decreased in the airway smooth muscle tissue from asthmatic patients compared with that from non-asthmatic patients, suggesting a potential role of p116^Rip expression in asthma pathogenesis.

Identification and Functional Analysis of a Flavonol Synthase Gene from Grape Hyacinth

Flavonols are important copigments that affect flower petal coloration. Flavonol synthase (FLS) catalyzes the conversion of dihydroflavonols to flavonols. In this study, we identified a FLS gene, MaFLS, expressed in petals of the ornamental monocot Muscari aucheri (grape hyacinth) and analyzed its spatial and temporal expression patterns. qRT-PCR analysis showed that MaFLS was predominantly expressed in the early stages of flower development. We next analyzed the in planta functions of MaFLS. Heterologous expression of MaFLS in Nicotiana tabacum (tobacco) resulted in a reduction in pigmentation in the petals, substantially inhibiting the expression of endogenous tobacco genes involved in anthocyanin biosynthesis (i.e., NtDFR, NtANS, and NtAN2) and upregulating the expression of NtFLS. The total anthocyanin content in the petals of the transformed tobacco plants was dramatically reduced, whereas the total flavonol content was increased. Our study suggests that MaFLS plays a key role in flavonol biosynthesis and flower coloration in grape hyacinth. Moreover, MaFLS may represent a new potential gene for molecular breeding of flower color modification and provide a basis for analyzing the effects of copigmentation on flower coloration in grape hyacinth.

Tuscan Varieties of Sweet Cherry Are Rich Sources of Ursolic and Oleanolic Acid: Protein Modeling Coupled to Targeted Gene Expression and Metabolite Analyses

The potential of six ancient Tuscan sweet cherry (Prunus avium L.) varieties as a source of health-promoting pentacyclic triterpenes is here evaluated by means of a targeted gene expression and metabolite analysis. By using a sequence homology criterion, we identify five oxidosqualene cyclase genes (OSCs) and three cytochrome P450s (CYP85s) that are putatively involved in the triterpene production pathway in sweet cherries. We performed 3D structure prediction and induced-fit docking using cation intermediates and reaction products for some OSCs to predict their function. We show that the Tuscan varieties have different amounts of ursolic and oleanolic acids and that these variations are related to different gene expression profiles. This study stresses the interest of valorizing ancient fruits as alternative sources of functional molecules with nutraceutical value. It also provides information on sweet cherry triterpene biosynthetic genes, which could be the object of follow-up functional studies.

Changes in digestive enzyme activities during early ontogeny of Seriola rivoliana

This study contributes to basic knowledge on the development of larval digestive enzyme activities of Seriola rivoliana, a carnivorous species that has shown high mortality in larval stage. The study was conducted under laboratory-controlled conditions until larvae reached 30 days after hatching (DAH). The specific activity of amylase and pepsin was analysed by spectrophotometric methods, and lipase, trypsin, chymotrypsin and alkaline phosphatase by fluorometry. The results showed that S. rivoliana larvae had different enzyme patterns depending on their developmental stage, and also when exogenous food was administered (rotifers and Artemia). At hatching (2.98 ± 0.14 mm SL), lipase, alkaline phosphatase, trypsin and chymotrypsin activities were detected, but the last two enzymes showed an activity close to zero. Trypsin, chymotrypsin, lipase and alkaline phosphatase sharply increased their activities after starting the first feeding. Amylase activity was not detected until 5 DAH (3.51 ± 0.18 mm SL) and had a peak on day 15 (4.59 ± 0.39 mm SL); no activity was observed from then on. Pepsin activity was detected approximately at 15 DAH, showing a constant increase onwards. Trypsin had a peak on day 15 and then decreased on the following days. Chymotrypsin had the highest peak at 5 DAH, then a sharp decrease on day seven (3.88 ± 0.11 mm SL), and it increased gradually until day 30 (11.71 ± 1.59 mm SL). Lipase showed the highest activity at 15 DAH and then decreased its value. Finally, alkaline phosphatase showed the highest value at 3 DAH (3.62 ± 0.06 mm SL); then, a severe decrease was observed with activity stability on the following days. In conclusion, S. rivoliana larvae had a similar pattern as that observed in other marine-carnivorous fish larvae, so it could be considered as juvenile at 20 DAH in terms of digestive physiology; based on our results and previous study, the weaning process could start after this age, which would allow establishing a co-feeding protocol using inert diet.

Functional and molecular characterization of UDP-glucuronosyltransferase 2 family in cynomolgus macaques

UDP-glucuronosyltransferases (UGTs) are essential enzymes metabolizing endogenous and exogenous chemicals. However, characteristics of UGTs have not been fully investigated in molecular levels of cynomolgus macaques, one of non-human primates widely used in preclinical drug metabolism studies. In this study, three UGT2A cDNAs (UGT2A1, 2A2, and 2A3) were isolated and characterized along with seven UGT2Bs previously identified in cynomolgus macaques. Several transcript variants were found in cynomolgus UGT2A1 and UGT2A2, like human orthologs. Cynomolgus UGT2A and UGT2B amino acid sequences were highly identical (87-96%) to their human counterparts. By phylogenetic analysis, all these cynomolgus UGT2s were more closely clustered with their human homologs than with dog, rat, or mouse UGT2s. Especially, UGT2As showed orthologous relationships between humans and cynomolgus macaques. All the cynomolgus UGT2 mRNAs were expressed in livers, jejunum, and/or kidneys abundantly, except that UGT2A1 and UGT2A2 mRNAs were predominantly expressed in nasal mucosa, like human UGT2s. UGT2A and UGT2B genes together form a gene cluster in the cynomolgus and human genome. Among the seven cynomolgus UGT2Bs heterologously expressed in yeast, UGT2B9 and UGT2B30 showed activities in estradiol 17-O-glucuronidation and morphine 3-O-glucuronidation but did not show activities in estradiol 3-O-glucuronidation, similar to human UGT2Bs. In liver microsomes, cynomolgus macaques showed higher estradiol 17-O-glucuronidase and morphine 3-O-glucuronidase activities than humans, suggesting functional activities of the responsible UGT2B enzymes in cynomolgus macaques. Therefore, cynomolgus UGT2s had overall molecular similarities to human UGT2s, but also showed some differences in UGT2B enzyme properties.

Characterization of function and genetic feature of UDP-glucuronosyltransferase in avian species

Birds are exposed to many xenobiotics during their lifetime. For accurate prediction of xenobiotic-induced toxic effects on avian species, it is necessary to understand metabolic capacities in a comprehensive range of bird species. However, there is a lack of information about avian xenobiotic metabolizing enzymes (XMEs), particularly in wild birds. Uridine diphosphate glucuronosyltransferase (UGT) is an XME that plays an important role in phase II metabolism in the livers of mammals and birds. This study was performed to determine the characteristics of UGT1E isoform in avian species, those are related to mammals UGT 1A. To understand the characteristics of avian UGT1E isoforms, in vitro metabolic activity and genetic characteristics were investigated. Furthermore, mRNA expression levels of all chicken UGT1E isoforms were measured. On in vitro enzymatic analysis, the white-tailed eagle, great horned owl, and Humboldt penguin showed lower UGT-dependent activity than domestic birds. In synteny analysis, carnivorous birds were shown to have fewer UGT1E isoforms than herbivorous and omnivorous birds, which may explain why they have lower in vitro UGT activity. These observations suggested that raptors and seabirds, in which UGT activity is low, may be at high risk if exposed to elevated levels of xenobiotics in the environment. Phylogenetic analysis suggested that avian UGT1Es have evolved independently from mammalian UGT1As. We identified the important UGT isoforms, such as UGT1E13, and suspected their substrate specificities in avian xenobiotic metabolism by phylogenetic and quantitative real-time PCR analysis. This is the first report regarding the genetic characteristics and interspecies differences of UGT1Es in avian species.

A novel polyketide synthase gene cluster in the plant pathogenic fungus Pseudocercospora fijiensis

Pseudocercospora fijiensis, causal agent of black Sigatoka of banana, produces polyketide synthase (PKS) pathways shown to be important in disease development by related Dothideomycete fungi. Genome analysis of the P. fijiensis PKS8-1 gene identified it as part of a gene cluster including genes encoding two transcription factors, a regulatory protein, a glyoxylase/beta-lactamase-like protein, an MFS transporter, a cytochrome P450, two aldo/keto reductases, a dehydrogenase, and a decarboxylase. Genome analysis of the related pathogens Pseudocercospora musae, Pseudocercospora eumusae, and Pseudocercospora pini-densiflorae, identified orthologous clusters containing a nearly identical combination of genes. Phylogenetic analysis of PKS8-1 identified homology to PKS proteins in the monodictyphenone and cladofulvin pathways in Aspergillus nidulans and Cladosporium fulvum, respectively. Analysis of clustered genes showed that the PKS8-1 cluster shares genes for enzymes involved in the production of the emodin intermediate in the monodictyphenone and cladofulvin pathways, but differs in many genes, suggesting production of a different metabolic product. Time course analysis of gene expression in infected banana showed up-regulation of PKS8-1 and four of eight clustered genes as early as 2 weeks post-inoculation and remaining high through 9 weeks. Overexpression of the pathway through constitutive expression of an aflR-like transcription factor gene in the cluster resulted in increased expression in culture of PKS8-1 as well as the four clustered genes that are up-regulated in infected plants. No differences were seen in timing or severity of disease symptoms with the overexpression strains relative to controls, however gene expression analysis showed no difference in expression in planta by an overexpression strain relative to controls. Thus constitutive expression of the aflR-like gene is not sufficient to upregulate the pathway above normal expression in planta. Pathway expression during all phases of disease development and conservation of the pathway in related Pseudocercospora species support a role for this pathway in disease.

Age- and sex-dependent variation in the activity of antioxidant enzymes in the brown trout (Salmo trutta)

Oxidative stress is defined as the imbalance between pro-oxidant and antioxidant molecules in favor of the former and it represents one of the main driving forces of aging. To counteract the harmful effects of oxidative stress, organisms evolved a complex antioxidant system. According to the free radical theory of aging, while the production of reactive oxygen species (ROS) increases with age, the antioxidant defenses decline. Although this relationship has been investigated in diverse vertebrate taxa, the information in fish is scant and inconsistent, particularly for wild populations. Thus, the aim of the present study was the investigation of age- and sex-related changes of the antioxidant enzymes activity in free-living individuals of the brown trout (Salmo trutta). We measured the activity of the main enzymes involved in antioxidant protection, namely superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST), as well as lipid peroxidation, in the gills and the liver dissected from brown trout (1+- to 5+-year-old). A significant age-dependent variation in the activity of antioxidant enzymes was noted, with the exception of CAT. GPx activity followed a significant increasing trend with age in both the organs, while SOD decreased in the liver. Increased GST activity was found in the gills only. Lipid peroxidation levels significantly decreased with age in both the organs. SOD and CAT showed sex-dependent differences in the liver of brown trout, with males showing lower enzymatic activity than females. Our data contribute to improve the knowledge on the relationship between antioxidant enzyme activity, aging, and sex in fish.

An overexpressed cytochrome P450 CYP439A1v3 confers deltamethrin resistance in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

Deltamethrin resistance in Laodelphax striatellus had been associated with its oxidative detoxification by overexpression of four cytochrome P450 monooxygenases like CYP353D1v2, CYP6FU1, CYP6AY3v2, and CYP439A1v3. The first three P450s have been validated for insecticide-metabolizing capability and only CYP6FU1 was found to degrade deltamethrin. In this study, an investigation was conducted to confirm the capability of CYP439A1v3 to degrade deltamethrin. The CYP439A1v3 was first expressed in Sf9 cell line and its recombinant enzyme was tested for metabolic activity against different insecticides using substrate depletion assay combined with metabolite identification. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and carbon monoxide (CO)-difference spectra analysis showed that the intact cytochrome P450 protein was successfully expressed. Tests with probe substrates proved its enzyme activity, as p-nitroanisole, ethoxycoumarin, and ethoxyresorufin were preferentially metabolized (specific activity 7.767 ± 1.22, 1.325 ± 0.37, and 0.355 ± 0.37 nmol/min per mg of protein, respectively) while only luciferin-HEGE was not. In vitro incubation of the recombinant CYP439A1v3 protein with deltamethrin revealed hydroxylation by producing hydroxydeltamethrin. On the contrary, no metabolite/metabolism was seen with nonpyrethroid insecticide, including imidacloprid, buprofezin, chlorpyrifos, and fipronil. To the best of our knowledge, this is the first study to link a CYP450 from family 439 to confer pyrethroid resistance to L. striatellus. This finding should help in the design of appropriate insecticide resistance management for control of this strain of L. striatellus.

Distinctive regulatory properties of pyruvate kinase 1 from Aedes aegypti mosquitoes

Female Aedes aegypti mosquitoes are vectors of arboviruses that cause diseases of public health significance. The discovery of new metabolic targets is crucial for improving mosquito control strategies. We recently demonstrated that glucose oxidation supports ammonia detoxification in A. aegypti. Pyruvate kinase (PK, EC 2.7.1.40) catalyzes the last step of the glycolytic pathway. In most organisms, one or more allosteric effectors control PK activity. However, the kinetic properties and structure of PK in mosquitoes have not been previously reported. In this study, two alternatively spliced mRNA variants (AaPK1 and AaPK2) that code for PKs were identified in the A. aegypti genome. The AaPK1 mRNA variant, which encodes a 529 amino acid protein with an estimated molecular weight of ∼57 kDa, was cloned. The protein was expressed in Escherichia coli and purified. The AaPK1 kinetic properties were identified. The recombinant protein was also crystallized and its 3D structure determined. We found that alanine, glutamine, proline, serine and fructose-1-phosphate displayed a classic allosteric activation on AaPK1. Ribulose-5-phosphate acted as an allosteric inhibitor of AaPK1 but its inhibitory effect was reversed by alanine, glutamine, proline and serine. Additionally, the allosteric activation of AaPK1 by amino acids was weakened by fructose-1,6-bisphosphate, whereas the allosteric activation of AaPK1 by alanine and serine was diminished by glucose-6-phosphate. The AaPK1 structure shows the presence of fructose-1,6-bisphosphate in the allosteric site. Together, our results reveal that specific amino acids and phosphorylated sugars tightly regulate conformational dynamics and catalytic changes of AaPK1. The distinctive AaPK1 allosteric properties support a complex role for this enzyme within mosquito metabolism.