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Biotechnology Letters Jun 2021Cytidine is an important raw material for nucleic acid health food and genetic engineering research. In recent years, it has shown irreplaceable effects in anti-virus,...
Cytidine is an important raw material for nucleic acid health food and genetic engineering research. In recent years, it has shown irreplaceable effects in anti-virus, anti-tumor, and AIDS drugs. Its biosynthetic pathway is complex and highly regulated. In this study, overexpression of uracil permease and a nucleoside transporter from Bacillus amyloliquefaciens related to cell membrane transport in Escherichia coli strain BG-08 was found to increase cytidine production in shake flask cultivation by 1.3-fold (0.91 ± 0.03 g/L) and 1.8-fold (1.26 ± 0.03 g/L) relative to that of the original strain (0.70 ± 0.03 g/L), respectively. Co-overexpression of uracil permease and a nucleoside transporter further increased cytidine yield by 2.7-fold (1.59 ± 0.05 g/L) compared with that of the original strain. These results indicate that the overexpressed uracil permease and nucleoside transporter can promote the accumulation of cytidine, and the two proteins play a synergistic role in the secretion of cytidine in Escherichia coli.
Topics: Bacillus amyloliquefaciens; Bacterial Proteins; Bacteriological Techniques; Batch Cell Culture Techniques; Biosynthetic Pathways; Cytidine; Escherichia coli; Membrane Transport Proteins; Nucleoside Transport Proteins; Protein Engineering
PubMed: 33646457
DOI: 10.1007/s10529-021-03103-3 -
Journal of Cell Science Jul 2023Mitochondrial protein import is essential for organellar biogenesis, and thereby for the sufficient supply of cytosolic ATP - which is particularly important for cells...
Mitochondrial protein import is essential for organellar biogenesis, and thereby for the sufficient supply of cytosolic ATP - which is particularly important for cells with high energy demands like neurons. This study explores the prospect of import machinery perturbation as a cause of neurodegeneration instigated by the accumulation of aggregating proteins linked to disease. We found that the aggregation-prone Tau variant (TauP301L) reduces the levels of components of the import machinery of the outer (TOM20, encoded by TOMM20) and inner membrane (TIM23, encoded by TIMM23) while associating with TOM40 (TOMM40). Intriguingly, this interaction affects mitochondrial morphology, but not protein import or respiratory function; raising the prospect of an intrinsic rescue mechanism. Indeed, TauP301L induced the formation of tunnelling nanotubes (TNTs), potentially for the recruitment of healthy mitochondria from neighbouring cells and/or the disposal of mitochondria incapacitated by aggregated Tau. Consistent with this, inhibition of TNT formation (and rescue) reveals Tau-induced import impairment. In primary neuronal cultures, TauP301L induced morphological changes characteristic of neurodegeneration. Interestingly, these effects were mirrored in cells where the import sites were blocked artificially. Our results reveal a link between aggregation-prone Tau and defective mitochondrial import relevant to disease.
Topics: Mitochondria; Membrane Transport Proteins; Protein Transport; Receptors, Cell Surface; Neurons; Mitochondrial Proteins; Mitochondrial Membrane Transport Proteins
PubMed: 37303235
DOI: 10.1242/jcs.260993 -
Biochemistry Nov 2021Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the... (Review)
Review
Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the export of this element require dedicated pathways that are dependent on oxidation state. Due to its solubility and kinetic lability, reduced ferrous iron (Fe) is useful to bacteria for import, chaperoning, and efflux. Once imported, ferrous iron may be loaded into apo and nascent enzymes and even sequestered into storage proteins under certain conditions. However, excess labile ferrous iron can impart toxicity as it may spuriously catalyze Fenton chemistry, thereby generating reactive oxygen species and leading to cellular damage. In response, it is becoming increasingly evident that bacteria have evolved Fe efflux pumps to deal with conditions of ferrous iron excess and to prevent intracellular oxidative stress. In this work, we highlight recent structural and mechanistic advancements in our understanding of prokaryotic ferrous iron import and export systems, with a focus on the connection of these essential transport systems to pathogenesis. Given the connection of these pathways to the virulence of many increasingly antibiotic resistant bacterial strains, a greater understanding of the mechanistic details of ferrous iron cycling in pathogens could illuminate new pathways for future therapeutic developments.
Topics: Anti-Bacterial Agents; Bacteria; Biological Transport; Catalysis; Homeostasis; Ion Transport; Iron; Kinetics; Membrane Proteins; Membrane Transport Proteins; Oxidation-Reduction; Oxidative Stress; Prokaryotic Cells; Reactive Oxygen Species; Solubility; Virulence
PubMed: 34670078
DOI: 10.1021/acs.biochem.1c00586 -
Current Opinion in Microbiology Jun 2021All mechanisms of clinical antibiotic resistance benefit from activities of polyspecific efflux pumps acting to reduce intracellular accumulation of toxins and... (Review)
Review
All mechanisms of clinical antibiotic resistance benefit from activities of polyspecific efflux pumps acting to reduce intracellular accumulation of toxins and antibiotics. In Gram-negative bacteria, the major polyspecific efflux transporters belong to the Resistance-Nodulation-cell Division (RND) superfamily of proteins, which are capable of expelling thousands of structurally diverse compounds. Recent structural and functional advances generated novel insights into mechanisms underlying the biochemical versatility of RND transporters. This opinion article reviews these mechanisms and discusses implications of the polyspecificity of RND transporters for bacterial survival and for the development of efflux pump inhibitors effective in clinics.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Biological Transport; Drug Resistance, Microbial; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacteria; Membrane Transport Proteins
PubMed: 33940284
DOI: 10.1016/j.mib.2021.03.009 -
NMR in Biomedicine Jan 2021X-linked creatine transporter deficiency (CTD) is one of the three types of cerebral creatine deficiency disorders. CTD arises from pathogenic variants in the X-linked...
X-linked creatine transporter deficiency (CTD) is one of the three types of cerebral creatine deficiency disorders. CTD arises from pathogenic variants in the X-linked gene SLC6A8. We report the first phosphorus ( P) MRS study of patients with CTD, where both phosphocreatine and total creatine concentrations were found to be markedly reduced. Despite the diminished role of creatine and phosphocreatine in oxidative phosphorylation in CTD, we found no elevation of lactate or lowered pH, indicating that the brain energy supply still largely relied on oxidative metabolism. Our results suggest that mitochondrial function is a potential therapeutic target for CTD.
Topics: Adolescent; Brain; Child; Child, Preschool; Creatine; Humans; Magnetic Resonance Imaging; Male; Membrane Transport Proteins; Metabolome; Oxidative Phosphorylation; Phosphorus; Proton Magnetic Resonance Spectroscopy
PubMed: 32990357
DOI: 10.1002/nbm.4419 -
Biotechnology Advances Oct 2022Aromatic compounds are ubiquitous in nature; they are the building blocks of abundant lignin, and constitute a substantial proportion of synthetic chemicals and organic... (Review)
Review
Aromatic compounds are ubiquitous in nature; they are the building blocks of abundant lignin, and constitute a substantial proportion of synthetic chemicals and organic pollutants. Uptake and degradation of aromatic compounds by bacteria have relevance in bioremediation, bio-based plastic recycling, and microbial conversion of lignocellulosic biomass into high-value commodity chemicals. While remarkable progress has been achieved in understanding aromatic metabolism in biodegraders, the membrane transporter systems responsible for uptake and efflux of aromatic compounds and their degradation products are still poorly understood. Membrane transporters are responsible for the initial recognition, uptake, and efflux of aromatic compounds; thus, in addition to controlling influx and efflux, the transporter system also forms part of stress tolerance mechanisms through excreting toxic metabolites. This review discusses significant advancements in our understanding of the nature and identity of the bacterial membrane transporter systems for aromatics, the molecular and structural basis of substrate recognition, mechanisms of translocation, functional regulation, and biotechnological applications. Most of these developments were enabled through the availability of crystal structures, advancements in computational biophysics, genome sequencing, omics studies, bioinformatics, and synthetic biology. We provide a comprehensive overview of recently reported knowledge on aromatic transporter systems in bacteria, point gaps in our understanding of the underlying translocation mechanisms, highlight existing limitations in harnessing transporter systems in synthetic biology applications, and suggest future research directions.
Topics: Bacteria; Biodegradation, Environmental; Lignin; Membrane Transport Proteins; Organic Chemicals
PubMed: 35398204
DOI: 10.1016/j.biotechadv.2022.107952 -
International Journal of Molecular... Aug 2022The proper regulation of nucleotide pools is essential for all types of cellular functions and depends on de novo nucleotide biosynthesis, salvage, and degradation... (Review)
Review
The proper regulation of nucleotide pools is essential for all types of cellular functions and depends on de novo nucleotide biosynthesis, salvage, and degradation pathways. Despite the apparent essentiality of these processes, a significant number of rare diseases associated with mutations in genes encoding various enzymes of these pathways have been already identified, and others are likely yet to come. However, knowledge on genetic alterations impacting on nucleoside and nucleobase transporters is still limited. At this moment three gene-encoding nucleoside and nucleobase transporter proteins have been reported to be mutated in humans, , , and , impacting on the expression and function of ENT1, ENT3, and CNT1, respectively. ENT1 alterations determine Augustine-null blood type and cause ectopic calcification during aging. ENT3 deficiency translates into various clinical manifestations and syndromes, altogether listed in the OMIM catalog as histiocytosis-lymphoadenopathy plus syndrome (OMIM#602782). CNT1 deficiency causes uridine-cytidineuria (URCTU) (OMIM#618477), a unique type of pyrimidineuria with an as yet not well-known clinical impact. Increasing knowledge on the physiological, molecular and structural features of these transporter proteins is helping us to better understand the biological basis behind the biochemical and clinical manifestations caused by these deficiencies. Moreover, they also support the view that some metabolic compensation might occur in these disturbances, because they do not seem to significantly impact nucleotide homeostasis, but rather other biological events associated with particular subtypes of transporter proteins.
Topics: Blood Group Antigens; Humans; Membrane Transport Proteins; Nucleoside Transport Proteins; Nucleosides; Nucleotides
PubMed: 35955904
DOI: 10.3390/ijms23158770 -
Molecular Microbiology Apr 2023The pentavalent organoarsenical arsinothricin (AST) is a natural product synthesized by the rhizosphere bacterium Burkholderia gladioli GSRB05. AST is a broad-spectrum...
The pentavalent organoarsenical arsinothricin (AST) is a natural product synthesized by the rhizosphere bacterium Burkholderia gladioli GSRB05. AST is a broad-spectrum antibiotic effective against human pathogens such as carbapenem-resistant Enterobacter cloacae. It is a non-proteogenic amino acid and glutamate mimetic that inhibits bacterial glutamine synthetase. The AST biosynthetic pathway is composed of a three-gene cluster, arsQML. ArsL catalyzes synthesis of reduced trivalent hydroxyarsinothricin (R-AST-OH), which is methylated by ArsM to the reduced trivalent form of AST (R-AST). In the culture medium of B. gladioli, both trivalent species appear as the corresponding pentavalent arsenicals, likely due to oxidation in air. ArsQ is an efflux permease that is proposed to transport AST or related species out of the cells, but the chemical nature of the actual transport substrate is unclear. In this study, B. gladioli arsQ was expressed in Escherichia coli and shown to confer resistance to AST and its derivatives. Cells of E. coli accumulate R-AST, and exponentially growing cells expressing arsQ take up less R-AST. The cells exhibit little transport of their pentavalent forms. Transport was independent of cellular energy and appears to be equilibrative. A homology model of ArsQ suggests that Ser320 is in the substrate binding site. A S320A mutant exhibits reduced R-AST-OH transport, suggesting that it plays a role in ArsQ function. The ArsQ permease is proposed to be an energy-independent uniporter responsible for downhill transport of the trivalent form of AST out of cells, which is oxidized extracellularly to the active form of the antibiotic.
Topics: Humans; Membrane Transport Proteins; Anti-Bacterial Agents; Escherichia coli; Arsenicals; Escherichia coli Proteins; Symporters; Biological Transport, Active
PubMed: 36785875
DOI: 10.1111/mmi.15045 -
Neurochemical Research Jan 2022Sodium-coupled neurotransmitter transporters play a fundamental role in the termination of synaptic neurotransmission, which makes them a major drug target. The... (Review)
Review
Sodium-coupled neurotransmitter transporters play a fundamental role in the termination of synaptic neurotransmission, which makes them a major drug target. The reconstitution of these secondary active transporters into liposomes has shed light on their molecular transport mechanisms. From the earliest days of the reconstitution technique up to today's single-molecule studies, insights from live functioning transporters have been indispensable for our understanding of their physiological impact. The two classes of sodium-coupled neurotransmitter transporters, the neurotransmitter: sodium symporters and the excitatory amino acid transporters, have vastly different molecular structures, but complementary proteoliposome studies have sought to unravel their ion-dependence and transport kinetics. Furthermore, reconstitution experiments have been used on both protein classes to investigate the role of e.g. the lipid environment, of posttranslational modifications, and of specific amino acid residues in transport. Techniques that allow the detection of transport at a single-vesicle resolution have been developed, and single-molecule studies have started to reveal single transporter kinetics, which will expand our understanding of how transport across the membrane is facilitated at protein level. Here, we review a selection of the results and applications where the reconstitution of the two classes of neurotransmitter transporters has been instrumental.
Topics: Biological Transport; Membrane Transport Proteins; Neurotransmitter Agents; Neurotransmitter Transport Proteins; Sodium
PubMed: 34347265
DOI: 10.1007/s11064-021-03413-y -
Journal of Agricultural and Food... May 2022The occurrence of plant diseases severely affects the quality and quantity of plant production. Plants adapt to the constant invasion of pathogens and gradually form a... (Review)
Review
The occurrence of plant diseases severely affects the quality and quantity of plant production. Plants adapt to the constant invasion of pathogens and gradually form a series of defense mechanisms, such as pathogen-associated molecular pattern-triggered immunity and microbial effector-triggered immunity. Moreover, many pathogens have evolved to inhibit the immune defense system and acquire plant nutrients as a result of their coevolution with plants. The sugars will eventually be exported transporters (SWEETs) are a novel family of sugar transporters that function as uniporters. They provide a channel for pathogens, including bacteria, fungi, and viruses, to hijack sugar from the host. In this review, we summarize the functions of SWEETs in nectar secretion, grain loading, senescence, and long-distance transport. We also focus on the interaction between the genes and pathogens. In addition, we provide insight into the potential application of genes to enhance disease resistance through the use of genome editing tools. The summary and perspective of this review will deepen our understanding of the role of during the process of pathogen infection and provide insights into resistance breeding.
Topics: Gene Expression Regulation, Plant; Membrane Transport Proteins; Plant Breeding; Plant Diseases; Plant Proteins; Plants; Sugars
PubMed: 35446562
DOI: 10.1021/acs.jafc.2c00582