scholarly journals Relative Rates of Amino Acid Import via the ABC Transporter GlnPQ Determine the Growth Performance of Lactococcus lactis

2015 ◽  
Vol 198 (3) ◽  
pp. 477-485 ◽  
Author(s):  
Faizah Fulyani ◽  
Gea K. Schuurman-Wolters ◽  
Dirk-Jan Slotboom ◽  
Bert Poolman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Lactococcus Lactis ◽  
Abc Transporter ◽  
Essential Amino Acid ◽  
Transmembrane Domain ◽  
Affinity Constant ◽  
Remarkable Feature ◽  
Content Type

ABSTRACTThe GlnPQ transporter fromLactococcus lactishas the remarkable feature of having two substrate-binding domains (SBDs) fused to the N terminus of the transmembrane domain (TMD), and thus four SBDs are present in the homodimeric complex. Although X-ray structures and ligand binding data are available for both SBDs, little is known of how different amino acids compete with each other for transport via GlnPQ. Here we show GlnPQ has a broader substrate specificity than previously thought, with the ability to take up asparagine, glutamine, and glutamic acid, albeit via different routes and with different affinities. Asparagine and glutamine compete with each other at the level of binding to SBD1 and SBD2 (with differences in dissociation constant), but at the same time SBD1 and SBD2 compete with each other at the level of interaction with the translocator domain (with differences in affinity constant and rate of transport). Although glutamine transport via SBD1 is outcompeted by physiological concentrations of asparagine, SBD2 ensures high rates of import of the essential amino acid glutamine. Taken together, this study demonstrates that even in the presence of competing asparagine concentrations, GlnPQ has a high capacity to transport glutamine, which matches the high needs of the cell for glutamine and glutamate.IMPORTANCEGlnPQ is an ATP-binding cassette (ABC) transporter for glutamine, glutamic acid, and asparagine. The system is essential in various Gram-positive bacteria, includingL. lactisand several pathogens. Here we show how the amino acids compete with each other for binding to the multiple SBDs of GlnPQ and how these SBDs compete with each other for substrate delivery to the transporter. Overall, our results show that GlnPQ has evolved to transport diverse substrates via different paths and to optimally acquire the abundant and essential amino acid glutamine.

scholarly journals Draft Genome Sequences of Three Amino Acid-Secreting Lactococcus lactis Strains

2020 ◽  
Vol 9 (16) ◽  
Author(s):  
Jhonatan A. Hernandez-Valdes ◽  
Anne de Jong ◽  
Jan Kok ◽  
Oscar P. Kuipers
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Lactococcus Lactis ◽  
Food Industry ◽  
Draft Genome ◽  
Bacterial Strains ◽  
Genome Sequences ◽  
Content Type ◽  
Acid Secreting

Three Lactococcus lactis strains with the ability to secrete various amino acids (leucine, isoleucine, methionine, valine, glutamic acid, and histidine) were sequenced in order to identify the mechanisms involved in the secretion. Amino acids contribute to flavor formation; therefore, bacterial strains with this ability are relevant for the food industry.

scholarly journals Non-essential nitrogen and protein utilization in the growing rat

1990 ◽  
Vol 64 (3) ◽  
pp. 653-661 ◽  
Author(s):  
J. Heger
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Essential Amino Acid ◽  
Essential Amino Acids ◽  
Protein Utilization ◽  
Biological Value ◽  
Growing Rats ◽  
Growing Rat ◽  
Per Se

Three series of nitrogen-balance experiments were carried out on growing rats fed on purified isonitrogenous diets (16 g N/kg) to study the importance of non-essential N and the essential:total N (E:T) ratio for attaining maximum N balance (NB) and biological value (BV) of protein. Minimum dietary levels of asparagine, proline and glutamic acid required for maximum NB and BV were estimated to be 1.0, 2.0 and 5.0 g/kg respectively. In an essential amino acid-based diet, the levels of individual amino acids were successively reduced to 110% of the requirement. Reducing the level of arginine, lysine or methionine + cystine resulted in a significant increase in NB and BV while the response of rats given the isoleucine-reduced diet significantly decreased. Addition of asparagine, proline and glutamic acid in the estimated minimum amounts to an essential amino acid-based diet resulted in a significant increase in NB and BV. A further significant increase was found when the levels of arginine, lysine and methionine + cystine in the diet were reduced to 110 % of the requirement. The performance of rats fed on the latter diet was similar to that of rats given a diet with the optimum E:T ratio. It is concluded that the optimum protein utilization may be influenced by the presence of some non-essential amino acids and by the surplus of some essential amino acids rather than by the E:T ratio per se.

scholarly journals Physiology and Substrate Specificity of Two Closely Related Amino Acid Transporters, SerP1 and SerP2, of Lactococcus lactis

2014 ◽  
Vol 197 (5) ◽  
pp. 951-958 ◽  
Author(s):  
Elke E. E. Noens ◽  
Juke S. Lolkema
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Lactococcus Lactis ◽  
Main Function ◽  
Content Type ◽  
High Affinity ◽  
Sequence Identity ◽  
Peptidoglycan Synthesis ◽  
Affinity Constants

TheserP1andserP2genes found adjacently on the chromosome ofLactococcus lactisstrains encode two members of the amino acid-polyamine-organocation (APC) superfamily of secondary transporters that share 61% sequence identity. SerP1 transportsl-serine,l-threonine, andl-cysteine with high affinity. Affinity constants (Km) are in the 20 to 40 μM range. SerP2 is adl-alanine/dl-serine/glycine transporter. The preferred substrate appears to bedl-alanine for which the affinities were found to be 38 and 20 μM for thedandlisomers, respectively. The common substratel-serine is a high-affinity substrate of SerP1 and a low-affinity substrate of SerP2 with affinity constants of 18 and 356 μM, respectively. Growth experiments demonstrate that SerP1 is the mainl-serine transporter responsible for optimal growth in media containing free amino acids as the sole source of amino acids. SerP2 is able to replace SerP1 in this role only in medium lacking the high-affinity substratesl-alanine and glycine. SerP2 plays an adverse role for the cell by being solely responsible for the uptake of toxicd-serine. The main function of SerP2 is in cell wall biosynthesis through the uptake ofd-alanine, an essential precursor in peptidoglycan synthesis. SerP2 has overlapping substrate specificity and shares 42% sequence identity with CycA ofEscherichia coli, a transporter whose involvement in peptidoglycan synthesis is well established. No evidence was obtained for a role of SerP1 and SerP2 in the excretion of excess amino acids during growth ofL. lactison protein/peptide-rich media.

scholarly journals Protein Targeting to the Parasitophorous Vacuole Membrane of Plasmodium falciparum

2011 ◽  
Vol 10 (6) ◽  
pp. 744-752 ◽  
Author(s):  
Saliha Eksi ◽  
Kim C. Williamson
Keyword(s):  
Amino Acids ◽  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Fluorescent Protein ◽  
Transmembrane Domain ◽  
Signal Sequence ◽  
Parasitophorous Vacuole ◽  
Reporter Protein ◽  
Content Type ◽  
Gfp Reporter

ABSTRACTRed blood cell (RBC) invasion and parasitophorous vacuole (PV) formation byPlasmodium falciparumare critical for the development and pathogenesis of malaria, a continuing global health problem. Expansion of the PV membrane (PVM) during growth is orchestrated by the parasite. This is particularly important in mature RBCs, which lack internal organelles and no longer actively synthesize membranes. Pfs16, a 16-kDa integral PVM protein expressed by gametocytes, was chosen as a model for studying the trafficking of material from the parasite across the PV space to the PVM. The locations of Pfs16-green fluorescent protein (GFP) reporter proteins containing distinct regions of Pfs16 were tracked from RBC invasion to emergence. Inclusion of the 53 C-terminal amino acids (aa) of Pfs16 to a GFP reporter construct already containing the N-terminal secretory signal sequence was sufficient for targeting to and retention on the PVM. An amino acid motif identified in this region was also found in seven other known PVM proteins. Removal of the 11 C-terminal aa did not affect PVM targeting, but membrane retention was decreased. Additionally, during emergence from the PVM and RBC, native Pfs16 and the full-length Pfs16-GFP reporter protein were found to concentrate on the ends of the gametocyte. Capping was not observed in constructs lacking the amino acids between the N-terminal secretory signal sequence and the transmembrane domain, suggesting that this region, which is not required for PVM targeting, is involved in capping. This is the first report to define the amino acid domains required for targeting to theP. falciparumPVM.

scholarly journals Protein reserves and muscle constituents of protein-depleted and repleted cocks

1967 ◽  
Vol 21 (3) ◽  
pp. 661-670 ◽  
Author(s):  
John H. Ashley ◽  
Hans Fisher
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Essential Amino Acid ◽  
Essential Amino Acids ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Fish Protein

1. Body-weight changes and nitrogen balance were studied, together with the concentration of various nitrogenous muscle components, in adult cocks before and after a 6-day period on a N-free diet and again after a 16-day repletion period on diets supplying various amounts and types of dietary N.2. In the first experiment a comparison was made during the repletion period between a fish-protein supplement and a supplement of glycine + glutamic acid added to an essential amino acid mixture.3. During the depletion period the muscle concentration of RNA, DNA and of two transaminase enzymes decreased significantly; during the repletion period these components increased again significantly, and usually to levels greater than the pre-depletion concentration. There were no differences in these responses obtained during repletion with the two N supplements, although the cocks given the glycine–glutamic acid supplement differed from those receiving fish protein in being in Negative N balance and in losing body-weight during the repletion period.4. In the second experiment one group of depleted cocks was given an essential amino acid mixture alone as the dietary N source and a second group this mixture supplemented by aspartic acid.5. A decrease in RNA and in the transaminase enzymes during depletion was followed by a significant increase during repletion, but the increase was greater for the group receiving the aspartic acid than for that receiving only the essential amino acid mixture.6. It was concluded that adding non-essential amino acids to a maintenance mixture of essential amino acids will permit greater repletion in mature cocks.7. The fluctuations in concentration of RNA and of certain enzymes with dietary protein supply may well be controlling factor in the regulation of N losses and accretions during protein deficiency and sufficiency.5. The relative constancy of muscle DNA in contrast to the fluctuations in other nitrogenous muscle constituents provides additional support for the concept of protein reserves.

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.

Dietary intake of tryptophan tied emotion-related impulsivity in humans

2019 ◽  
pp. 1-8 ◽  
Author(s):  
Florian Javelle ◽  
Descartes Li ◽  
Philipp Zimmer ◽  
Sheri L. Johnson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Food Intake ◽  
Essential Amino Acid ◽  
Food Habits ◽  
Psychological Disorder ◽  
Serotonin Synthesis ◽  
Amino Acid Tryptophan ◽  
Pass Through ◽  
Three Factor

Abstract. Emotion-related impulsivity, defined as the tendency to say or do things that one later regret during periods of heightened emotion, has been tied to a broad range of psychopathologies. Previous work has suggested that emotion-related impulsivity is tied to an impaired function of the serotonergic system. Central serotonin synthesis relies on the intake of the essential amino acid, tryptophan and its ability to pass through the blood brain barrier. Objective: The aim of this study was to determine the association between emotion-related impulsivity and tryptophan intake. Methods: Undergraduate participants (N = 25, 16 women, 9 men) completed a self-rated measure of impulsivity (Three Factor Impulsivity Index, TFI) and daily logs of their food intake and exercise. These data were coded using the software NutriNote to evaluate intakes of tryptophan, large neutral amino acids, vitamins B6/B12, and exercise. Results: Correlational analyses indicated that higher tryptophan intake was associated with significantly lower scores on two out of three subscales of the TFI, Pervasive Influence of Feelings scores r =  –.502, p < . 010, and (lack-of) Follow-Through scores, r =  –.407, p < . 050. Conclusion: Findings provide further evidence that emotion-related impulsivity is correlated to serotonergic indices, even when considering only food habits. It also suggests the need for more research on whether tryptophan supplements might be beneficial for impulsive persons suffering from a psychological disorder.

scholarly journals Tailoring a Global Iron Regulon to a Uropathogen

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rajdeep Banerjee ◽  
Erin Weisenhorn ◽  
Kevin J. Schwartz ◽  
Kevin S. Myers ◽  
Jeremy D. Glasner ◽  
...  
Keyword(s):  
Amino Acids ◽  
Urinary Tract ◽  
Amino Acid ◽  
Regulatory Network ◽  
Iron Homeostasis ◽  
Iron Limitation ◽  
Content Type ◽  
E Coli ◽  
General Stress ◽  
K 12

ABSTRACT Pathogenicity islands and plasmids bear genes for pathogenesis of various Escherichia coli pathotypes. Although there is a basic understanding of the contribution of these virulence factors to disease, less is known about variation in regulatory networks in determining disease phenotypes. Here, we dissected a regulatory network directed by the conserved iron homeostasis regulator, ferric uptake regulator (Fur), in uropathogenic E. coli (UPEC) strain CFT073. Comparing anaerobic genome-scale Fur DNA binding with Fur-dependent transcript expression and protein levels of the uropathogen to that of commensal E. coli K-12 strain MG1655 showed that the Fur regulon of the core genome is conserved but also includes genes within the pathogenicity/genetic islands. Unexpectedly, regulons indicative of amino acid limitation and the general stress response were also indirectly activated in the uropathogen fur mutant, suggesting that induction of the Fur regulon increases amino acid demand. Using RpoS levels as a proxy, addition of amino acids mitigated the stress. In addition, iron chelation increased RpoS to the same levels as in the fur mutant. The increased amino acid demand of the fur mutant or iron chelated cells was exacerbated by aerobic conditions, which could be partly explained by the O2-dependent synthesis of the siderophore aerobactin, encoded by an operon within a pathogenicity island. Taken together, these data suggest that in the iron-poor environment of the urinary tract, amino acid availability could play a role in the proliferation of this uropathogen, particularly if there is sufficient O2 to produce aerobactin. IMPORTANCE Host iron restriction is a common mechanism for limiting the growth of pathogens. We compared the regulatory network controlled by Fur in uropathogenic E. coli (UPEC) to that of nonpathogenic E. coli K-12 to uncover strategies that pathogenic bacteria use to overcome iron limitation. Although iron homeostasis functions were regulated by Fur in the uropathogen as expected, a surprising finding was the activation of the stringent and general stress responses in the uropathogen fur mutant, which was rescued by amino acid addition. This coordinated global response could be important in controlling growth and survival under nutrient-limiting conditions and during transitions from the nutrient-rich environment of the lower gastrointestinal (GI) tract to the more restrictive environment of the urinary tract. The coupling of the response of iron limitation to increased demand for amino acids could be a critical attribute that sets UPEC apart from other E. coli pathotypes.

scholarly journals The Carboxy-Terminal Region ofFlavobacterium johnsoniaeSprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

2019 ◽  
Vol 201 (19) ◽  
Author(s):  
Surashree S. Kulkarni ◽  
Joseph J. Johnston ◽  
Yongtao Zhu ◽  
Zachary T. Hying ◽  
Mark J. McBride
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cell Surface ◽  
Type A ◽  
Secretion System ◽  
Gliding Motility ◽  
Foreign Protein ◽  
Type B ◽  
Content Type ◽  
Type Ix Secretion System

ABSTRACTFlavobacterium johnsoniaeSprB moves rapidly along the cell surface, resulting in gliding motility. SprB secretion requires the type IX secretion system (T9SS). Proteins secreted by the T9SS typically have conserved C-terminal domains (CTDs) belonging to the type A CTD or type B CTD family. Attachment of 70- to 100-amino-acid type A CTDs to a foreign protein allows its secretion. Type B CTDs are common but have received little attention. Secretion of the foreign protein superfolder green fluorescent protein (sfGFP) fused to regions spanning the SprB type B CTD (sfGFP-CTDSprB) was analyzed. CTDs of 218 amino acids or longer resulted in secretion of sfGFP, whereas a 149-amino-acid region did not. Some sfGFP was secreted in soluble form, whereas the rest was attached on the cell surface. Surface-attached sfGFP was rapidly propelled along the cell, suggesting productive interaction with the motility machinery. This did not result in rapid cell movement, which apparently requires additional regions of SprB. Secretion of sfGFP-CTDSprBrequired coexpression withsprF, which lies downstream ofsprB. SprF is similar in sequence toPorphyromonas gingivalisPorP. MostF. johnsoniaegenes encoding proteins with type B CTDs lie immediately upstream ofporP/sprF-like genes. sfGFP was fused to the type B CTD from one such protein (Fjoh_3952). This resulted in secretion of sfGFP only when it was coexpressed with its cognate PorP/SprF-like protein. These results highlight the need for extended regions of type B CTDs and for coexpression with the appropriate PorP/SprF-like protein for efficient secretion and cell surface localization of cargo proteins.IMPORTANCETheF. johnsoniaegliding motility adhesin SprB is delivered to the cell surface by the type IX secretion system (T9SS) and is rapidly propelled along the cell by the motility machinery. How this 6,497-amino-acid protein interacts with the secretion and motility machines is not known. Fusion of the C-terminal 218 amino acids of SprB to a foreign cargo protein resulted in its secretion, attachment to the cell surface, and rapid movement by the motility machinery. Efficient secretion of SprB required coexpression with the outer membrane protein SprF. Secreted proteins that have sequence similarity to SprB in their C-terminal regions are common in the phylumBacteroidetesand may have roles in adhesion, motility, and virulence.

scholarly journals The Diverse Functions of Non-Essential Amino Acids in Cancer

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 675 ◽  
Author(s):  
Bo-Hyun Choi ◽  
Jonathan L. Coloff
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cancer Therapy ◽  
Metabolic Pathways ◽  
Essential Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Essential Amino Acids ◽  
Redox Status ◽  
Antioxidant Systems

Far beyond simply being 11 of the 20 amino acids needed for protein synthesis, non-essential amino acids play numerous important roles in tumor metabolism. These diverse functions include providing precursors for the biosynthesis of macromolecules, controlling redox status and antioxidant systems, and serving as substrates for post-translational and epigenetic modifications. This functional diversity has sparked great interest in targeting non-essential amino acid metabolism for cancer therapy and has motivated the development of several therapies that are either already used in the clinic or are currently in clinical trials. In this review, we will discuss the important roles that each of the 11 non-essential amino acids play in cancer, how their metabolic pathways are linked, and how researchers are working to overcome the unique challenges of targeting non-essential amino acid metabolism for cancer therapy.

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