scholarly journals Cloning, Expression, and Functional Characterization of Secondary Amino Acid Transporters of Lactococcus lactis

2012 ◽  
Vol 195 (2) ◽  
pp. 340-350 ◽  
Author(s):  
Hein Trip ◽  
Niels L. Mulder ◽  
Juke S. Lolkema
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Lactococcus Lactis ◽  
Aromatic Amino Acids ◽  
Amino Acid Transporter ◽  
Amino Acid Transporters ◽  
Acid Uptake ◽  
Content Type ◽  
Secondary Amino ◽  
Acid Transporter

ABSTRACTFourteen genes encoding putative secondary amino acid transporters were identified in the genomes ofLactococcus lactissubsp.cremorisstrains MG1363 and SK11 andL. lactissubsp. lactisstrains IL1403 and KF147, 12 of which were common to all four strains. Amino acid uptake inL. lactiscells overexpressing the genes revealed transporters specific for histidine, lysine, arginine, agmatine, putrescine, aromatic amino acids, acidic amino acids, serine, and branched-chain amino acids. Substrate specificities were demonstrated by inhibition profiles determined in the presence of excesses of the other amino acids. Four knockout mutants, lacking the lysine transporter LysP, the histidine transporter HisP (formerly LysQ), the acidic amino acid transporter AcaP (YlcA), or the aromatic amino acid transporter FywP (YsjA), were constructed. The LysP, HisP, and FywP deletion mutants showed drastically decreased rates of uptake of the corresponding substrates at low concentrations. The same was observed for the AcaP mutant with aspartate but not with glutamate. In rich M17 medium, the deletion of none of the transporters affected growth. In contrast, the deletion of the HisP, AcaP, and FywP transporters did affect growth in a defined medium with free amino acids as the sole amino acid source. HisP was essential at low histidine concentrations, and AcaP was essential in the absence of glutamine. FywP appeared to play a role in retaining intracellularly synthesized aromatic amino acids when these were not added to the medium. Finally, HisP, AcaP, and FywP did not play a role in the excretion of accumulated histidine, glutamate, or phenylalanine, respectively, indicating the involvement of other transporters.

scholarly journals The Regulation and Function of the L-Type Amino Acid Transporter 1 (LAT1) in Cancer

2018 ◽  
Vol 19 (8) ◽  
pp. 2373 ◽  
Author(s):  
Travis Salisbury ◽  
Subha Arthur
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cancer Cells ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Amino Acid Transporter ◽  
Amino Acid Transporters ◽  
Acid Uptake ◽  
Cancer Pathways ◽  
Acid Transporter

The progression of cancer is associated with increases in amino acid uptake by cancer cells. Upon their entry into cells through specific transporters, exogenous amino acids are used to synthesize proteins, nucleic acids and lipids and to generate ATP. The essential amino acid leucine is also important for maintaining cancer-associated signaling pathways. By upregulating amino acid transporters, cancer cells gain greater access to exogenous amino acids to support chronic proliferation, maintain metabolic pathways, and to enhance certain signal transduction pathways. Suppressing cancer growth by targeting amino acid transporters will require an in-depth understanding of how cancer cells acquire amino acids, in particular, the transporters involved and which cancer pathways are most sensitive to amino acid deprivation. L-Type Amino Acid Transporter 1 (LAT1) mediates the uptake of essential amino acids and its expression is upregulated during the progression of several cancers. We will review the upstream regulators of LAT1 and the downstream effects caused by the overexpression of LAT1 in cancer cells.

ACE2 and gut amino acid transport

2020 ◽  
Vol 134 (21) ◽  
pp. 2823-2833 ◽  
Author(s):  
Simone M.R. Camargo ◽  
Raphael N. Vuille-dit-Bille ◽  
Chantal F. Meier ◽  
François Verrey
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Amino Acid ◽  
Amino Acid Transporter ◽  
Neutral Amino Acid ◽  
Amino Acid Transporters ◽  
Type I ◽  
Small Intestinal Mucosa ◽  
Neutral Amino Acid Transporter ◽  
Acid Transporter

Abstract ACE2 is a type I membrane protein with extracellular carboxypeptidase activity displaying a broad tissue distribution with highest expression levels at the brush border membrane (BBM) of small intestine enterocytes and a lower expression in stomach and colon. In small intestinal mucosa, ACE2 mRNA expression appears to increase with age and to display higher levels in patients taking ACE-inhibitors (ACE-I). There, ACE2 protein heterodimerizes with the neutral amino acid transporter Broad neutral Amino acid Transporter 1 (B0AT1) (SLC6A19) or the imino acid transporter Sodium-dependent Imino Transporter 1 (SIT1) (SLC6A20), associations that are required for the surface expression of these transport proteins. These heterodimers can form quaternary structures able to function as binding sites for SARS-CoV-2 spike glycoproteins. The heterodimerization of the carboxypeptidase ACE2 with B0AT1 is suggested to favor the direct supply of substrate amino acids to the transporter, but whether this association impacts the ability of ACE2 to mediate viral infection is not known. B0AT1 mutations cause Hartnup disorder, a condition characterized by neutral aminoaciduria and, in some cases, pellagra-like symptoms, such as photosensitive rash, diarrhea, and cerebellar ataxia. Correspondingly, the lack of ACE2 and the concurrent absence of B0AT1 expression in small intestine causes a decrease in l-tryptophan absorption, niacin deficiency, decreased intestinal antimicrobial peptide production, and increased susceptibility to inflammatory bowel disease (IBD) in mice. Thus, the abundant expression of ACE2 in small intestine and its association with amino acid transporters appears to play a crucial role for the digestion of peptides and the absorption of amino acids and, thereby, for the maintenance of structural and functional gut integrity.

scholarly journals Aromatic Amino Acid Auxotrophs Constructed by Recombinant Marker Exchange in Methylophilus methylotrophus AS1 Cells Expressing the aroP-Encoded Transporter of Escherichia coli

2009 ◽  
Vol 76 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Yurgis A. V. Yomantas ◽  
Irina L. Tokmakova ◽  
Natalya V. Gorshkova ◽  
Elena G. Abalakina ◽  
Svetlana M. Kazakova ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Target Genes ◽  
Aromatic Amino Acids ◽  
Amino Acid Transporter ◽  
Methylotrophic Bacteria ◽  
Methylophilus Methylotrophus ◽  
Acid Transporter

ABSTRACT The isolation of auxotrophic mutants, which is a prerequisite for a substantial genetic analysis and metabolic engineering of obligate methylotrophs, remains a rather complicated task. We describe a novel method of constructing mutants of the bacterium Methylophilus methylotrophus AS1 that are auxotrophic for aromatic amino acids. The procedure begins with the Mu-driven integration of the Escherichia coli gene aroP, which encodes the common aromatic amino acid transporter, into the genome of M. methylotrophus. The resulting recombinant strain, with improved permeability to certain amino acids and their analogues, was used for mutagenesis. Mutagenesis was carried out by recombinant substitution of the target genes in the chromosome by linear DNA using the FLP-excisable marker flanked with cloned homologous arms longer than 1,000 bp. M. methylotrophus AS1 genes trpE, tyrA, pheA, and aroG were cloned in E. coli, sequenced, disrupted in vitro using a Kmr marker, and electroporated into an aroP carrier recipient strain. This approach led to the construction of a set of marker-less M. methylotrophus AS1 mutants auxotrophic for aromatic amino acids. Thus, introduction of foreign amino acid transporter genes appeared promising for the following isolation of desired auxotrophs on the basis of different methylotrophic bacteria.

scholarly journals The amino acid transporter CG1139 is required for retrograde transport and fast recovery of gut enterocytes after Serratia marcescens intestinal infection

2021 ◽  
Author(s):  
Catherine Socha ◽  
Ines S. Pais ◽  
Kwang-Zin Lee ◽  
Matthieu Lestradet ◽  
Dominique Ferrandon
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Serratia Marcescens ◽  
Retrograde Transport ◽  
Resistance Mechanisms ◽  
Amino Acid Transporter ◽  
Amino Acid Transporters ◽  
Intestinal Infections ◽  
Acid Transporter ◽  
Normal Thickness

The intestinal tract is constantly exposed to microbes. Severe infections can arise following the ingestion of pathogenic microbes from contaminating food or water sources. The host directly fights off ingested pathogens with resistance mechanisms, the immune response, or withstands and repairs the damages inflicted either by virulence factors or the host immune effectors, through tolerance/resilience mechanisms. In a previous study, we reported the existence in Drosophila melanogaster of a novel evolutionarily conserved resilience mechanism to intestinal infections with a hemolysin-positive Serratia marcescens strain (SmDb11), the purge of the apical cytoplasm of enterocytes. The epithelium becomes very thin and recovers rapidly, regaining its normal thickness within several hours. Here, we found that this recovery of gut enterocyte morphology is based on the host internal reserves and not on ingested food. Indeed, we observed a retrograde transport of amino acids from the host hemolymph to the enterocytes. We have identified several amino acid transporters required for recovery and we focused on the SLC36 family transporter CG1139. CG1139 is required for the retrograde transport of amino acids. RNA sequencing revealed that genes involved in the positive regulation of growth were observed in wild-type but not CG1139 mutant guts, in which the expression of Myc and genes involved in Insulin signaling is down-regulated. Functional analysis revealed that Myc is also required for the recovery of the thick gut epithelium after infection. Altogether, our results show the importance of an amino acid transporter in the fast regrowth of the enterocytes upon infection. Unexpectedly, we found that this transporter acts non cell-autonomously and can regulate the transcription of other genes, suggesting a signaling function of CG1139 that therefore appears to act as a transceptor.

The amino acid transporter SNAT2 mediates l-proline-induced differentiation of ES cells

2011 ◽  
Vol 300 (6) ◽  
pp. C1270-C1279 ◽  
Author(s):  
Boon Siang Nicholas Tan ◽  
Ana Lonic ◽  
Michael B. Morris ◽  
Peter D. Rathjen ◽  
Joy Rathjen
Keyword(s):  
Amino Acids ◽  
Cell Differentiation ◽  
Amino Acid ◽  
Biological Activities ◽  
Es Cells ◽  
Embryonic Stem ◽  
Amino Acid Transporter ◽  
Acid Uptake ◽  
Es Cell ◽  
Acid Transporter

There is an increasing appreciation that amino acids can act as signaling molecules in the regulation of cellular processes through modulation of intracellular cell signaling pathways. In culture, embryonic stem (ES) cells can be differentiated to a second, pluripotent cell population, early primitive ectoderm-like cells in response to biological activities within the conditioned medium MEDII. The amino acid l-proline has been identified as a component of MEDII required for ES cell differentiation. Here, we define the primary l-proline transporter on ES and early primitive ectoderm-like cells as sodium-coupled neutral amino acid transporter 2 (SNAT2). SNAT2 uptake of l-proline can be inhibited by the addition of millimolar concentrations of other substrates. The addition of excess amino acids was used to regulate the uptake of l-proline by ES cells, and the effect on differentiation was analyzed. The ability of SNAT2 substrates, but not other amino acids, to prevent changes in morphology, gene expression, and differentiation kinetics suggested that l-proline uptake through SNAT2 was required for ES cell differentiation. These data reveal an unexpected role for amino acid uptake and the amino acid transporter SNAT2 in regulation of pluripotent cells in culture and provides a number of specific, inexpensive, and nontoxic culture additives with the potential to improve the quality of ES cell culture.

scholarly journals Amino acid transporters in the regulation of insulin secretion and signalling

2019 ◽  
Vol 47 (2) ◽  
pp. 571-590 ◽  
Author(s):  
Kiran Javed ◽  
Stephen J. Fairweather
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Insulin Secretion ◽  
Amino Acid ◽  
Insulin Signalling ◽  
Amino Acid Transporter ◽  
Fibroblast Growth Factor 21 ◽  
Amino Acid Transporters ◽  
Acid Transporter

Abstract Amino acids are increasingly recognised as modulators of nutrient disposal, including their role in regulating blood glucose through interactions with insulin signalling. More recently, cellular membrane transporters of amino acids have been shown to form a pivotal part of this regulation as they are primarily responsible for controlling cellular and circulating amino acid concentrations. The availability of amino acids regulated by transporters can amplify insulin secretion and modulate insulin signalling in various tissues. In addition, insulin itself can regulate the expression of numerous amino acid transporters. This review focuses on amino acid transporters linked to the regulation of insulin secretion and signalling with a focus on those of the small intestine, pancreatic β-islet cells and insulin-responsive tissues, liver and skeletal muscle. We summarise the role of the amino acid transporter B0AT1 (SLC6A19) and peptide transporter PEPT1 (SLC15A1) in the modulation of global insulin signalling via the liver-secreted hormone fibroblast growth factor 21 (FGF21). The role of vesicular vGLUT (SLC17) and mitochondrial SLC25 transporters in providing glutamate for the potentiation of insulin secretion is covered. We also survey the roles SNAT (SLC38) family and LAT1 (SLC7A5) amino acid transporters play in the regulation of and by insulin in numerous affective tissues. We hypothesise the small intestine amino acid transporter B0AT1 represents a crucial nexus between insulin, FGF21 and incretin hormone signalling pathways. The aim is to give an integrated overview of the important role amino acid transporters have been found to play in insulin-regulated nutrient signalling.

The Role of Large Neutral Amino Acid Transporter (LAT1) in Cancer

2019 ◽  
Vol 19 (11) ◽  
pp. 863-876 ◽  
Author(s):  
Xinjie Lu
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Metabolic Networks ◽  
Amino Acid Transporter ◽  
Amino Acid Transporters ◽  
Large Neutral Amino Acid ◽  
Pharmaceutical Drugs ◽  
Cationic Amino Acid ◽  
Acid Transporter

Background: The solute carrier family 7 (SLC7) can be categorically divided into two subfamilies, the L-type amino acid transporters (LATs) including SLC7A5-13, and SLC7A15, and the cationic amino acid transporters (CATs) including SLC7A1-4 and SLC7A14. Members of the CAT family transport predominantly cationic amino acids by facilitating diffusion with intracellular substrates. LAT1 (also known as SLC7A5), is defined as a heteromeric amino acid transporter (HAT) interacting with the glycoprotein CD98 (SLC3A2) through a conserved disulfide to uptake not only large neutral amino acids, but also several pharmaceutical drugs to cells. Methods: In this review, we provide an overview of the interaction of the structure-function of LAT1 and its essential role in cancer, specifically, its role at the blood-brain barrier (BBB) to facilitate the transport of thyroid hormones, pharmaceuticals (e.g., I-DOPA, gabapentin), and metabolites into the brain. Results: LAT1 expression increases as cancers progress, leading to higher expression levels in highgrade tumors and metastases. In addition, LAT1 plays a crucial role in cancer-associated reprogrammed metabolic networks by supplying tumor cells with essential amino acids. Conclusion: The increasing understanding of the role of LAT1 in cancer has led to an increase in interest surrounding its potential as a drug target for cancer treatment.

scholarly journals Transcriptome-Wide Analysis of Nitrogen-Regulated Genes in Tea Plant (Camellia sinensis L. O. Kuntze) and Characterization of Amino Acid Transporter CsCAT9.1

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1218
Author(s):  
Xinwan Zhang ◽  
Hongling Liu ◽  
Elizabeth Pilon-Smits ◽  
Wei Huang ◽  
Pu Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Camellia Sinensis ◽  
Transcript Level ◽  
Amino Acid Transporter ◽  
Tea Plant ◽  
Differentially Expressed ◽  
Acid Uptake ◽  
Acid Transporter ◽  
Tea Plants

The vigor of tea plants (Camellia sinensis) and tea quality are strongly influenced by the abundance and forms of nitrogen, principally NO3−, NH4+, and amino acids. Mechanisms to access different nitrogen sources and the regulatory cues remain largely elusive in tea plants. A transcriptome analysis was performed to categorize differentially expressed genes (DEGs) in roots and young leaves during the early response to four nitrogen treatments. Relative to the continuously nitrogen-replete control, the three nitrogen-deprived and resupplied treatments shared 237 DEGs in the shoots and 21 DEGs in the root. Gene-ontology characterization revealed that transcripts encoding genes predicted to participate in nitrogen uptake, assimilation, and translocation were among the most differentially expressed after exposure to the different nitrogen regimes. Because of its high transcript level regardless of nitrogen condition, a putative amino acid transporter, TEA020444/CsCAT9.1, was further characterized in Arabidopsis and found to mediate the acquisition of a broad spectrum of amino acids, suggesting a role in amino acid uptake, transport, and deposition in sinks as an internal reservoir. Our results enhance our understanding of nitrogen-regulated transcript level patterns in tea plants and pinpoint candidate genes that function in nitrogen transport and metabolism, allowing tea plants to adjust to variable nitrogen environments.

scholarly journals The Amino Acid-mTORC1 Pathway Mediates APEC TW-XM-Induced Inflammation in bEnd.3 Cells

2021 ◽  
Vol 22 (17) ◽  
pp. 9245
Author(s):  
Dong Zhang ◽  
Shu Xu ◽  
Yiting Wang ◽  
Peng Bin ◽  
Guoqiang Zhu
Keyword(s):  
Amino Acid ◽  
Inflammatory Response ◽  
Inflammatory Responses ◽  
Excitatory Amino Acid ◽  
Amino Acid Uptake ◽  
Amino Acid Transporter ◽  
Amino Acid Transporters ◽  
Acid Uptake ◽  
Mtorc1 Pathway ◽  
Acid Transporter

The blood–brain barrier (BBB) is key to establishing and maintaining homeostasis in the central nervous system (CNS); meningitis bacterial infection can disrupt the integrity of BBB by inducing an inflammatory response. The changes in the cerebral uptake of amino acids may contribute to inflammatory response during infection and were accompanied by high expression of amino acid transporters leading to increased amino acid uptake. However, it is unclear whether amino acid uptake is changed and how to affect inflammatory responses in mouse brain microvascular endothelial (bEnd.3) cells in response to Avian Pathogenic Escherichia coli TW-XM (APEC XM) infection. Here, we firstly found that APEC XM infection could induce serine (Ser) and glutamate (Glu) transport from extracellular into intracellular in bEnd.3 cells. Meanwhile, we also shown that the expression sodium-dependent neutral amino acid transporter 2 (SNAT2) for Ser and excitatory amino acid transporter 4 (EAAT4) for Glu was also significantly elevated during infection. Then, in amino acid deficiency or supplementation medium, we found that Ser or Glu transport were involving in increasing SNAT2 or EAAT4 expression, mTORC1 (mechanistic target of rapamycin complex 1) activation and inflammation, respectively. Of note, Ser or Glu transport were inhibited after SNAT2 silencing or EAAT4 silencing, resulting in inhibition of mTORC1 pathway activation, and inflammation compared with the APEC XM infection group. Moreover, pEGFP-SNAT2 overexpression and pEGFP-EAAT4 overexpression in bEnd.3 cells all could promote amino acid uptake, activation of the mTORC1 pathway and inflammation during infection. We further found mTORC1 silencing could inhibit inflammation, the expression of SNAT2 and EAAT4, and amino acid uptake. Taken together, our results demonstrated that APEC TW-XM infection can induce Ser or Glu uptake depending on amino acid transporters transportation, and then activate amino acid-mTORC1 pathway to induce inflammation in bEnd.3 cells.

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