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 Genetic and Biochemical Characterization of OXA-535, a Distantly Related OXA-48-Like β-Lactamase

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
L. Dabos ◽  
A. B. Jousset ◽  
R. A. Bonnin ◽  
N. Fortineau ◽  
A. Zavala ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Amino Acid Sequence Identity ◽  
Biochemical Characterization ◽  
Content Type ◽  
Sequence Identity

ABSTRACT OXA-535 is a chromosome-encoded carbapenemase of Shewanella bicestrii JAB-1 that shares only 91.3% amino acid sequence identity with OXA-48. Catalytic efficiencies are similar to those of OXA-48 for most β-lactams, except for ertapenem, where a 2,000-fold-higher efficiency was observed with OXA-535. OXA-535 and OXA-436, a plasmid-encoded variant of OXA-535 differing by three amino acids, form a novel cluster of distantly related OXA-48-like carbapenemases. Comparison of blaOXA-535 and blaOXA-436 genetic environments suggests that an ISCR1 may be responsible for blaOXA-436 gene mobilization from the chromosome of Shewanella spp. to plasmids.

scholarly journals A Novelmeso-Diaminopimelate Dehydrogenase from Symbiobacterium thermophilum: Overexpression, Characterization, and Potential for d-Amino Acid Synthesis

2012 ◽  
Vol 78 (24) ◽  
pp. 8595-8600 ◽  
Author(s):  
Xiuzhen Gao ◽  
Xi Chen ◽  
Weidong Liu ◽  
Jinhui Feng ◽  
Qiaqing Wu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Enantiomeric Excess ◽  
Acid Synthesis ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Gene Encoding ◽  
Amino Acid Synthesis ◽  
Content Type

ABSTRACTmeso-Diaminopimelate dehydrogenase (meso-DAPDH) is an NADP+-dependent enzyme which catalyzes the reversible oxidative deamination on thed-configuration ofmeso-2,6-diaminopimelate to producel-2-amino-6-oxopimelate. In this study, the gene encoding ameso-diaminopimelate dehydrogenase fromSymbiobacterium thermophilumwas cloned and expressed inEscherichia coli. In addition to the native substratemeso-2,6-diaminopimelate, the purified enzyme also showed activity towardd-alanine,d-valine, andd-lysine. This enzyme catalyzed the reductive amination of 2-keto acids such as pyruvic acid to generated-amino acids in up to 99% conversion and 99% enantiomeric excess. Sincemeso-diaminopimelate dehydrogenases are known to be specific tomeso-2,6-diaminopimelate, this is a unique wild-typemeso-diaminopimelate dehydrogenase with a more relaxed substrate specificity and potential ford-amino acid synthesis. The enzyme is the most stablemeso-diaminopimelate dehydrogenase reported to now. Two amino acid residues (F146 and M152) in the substrate binding sites ofS. thermophilum meso-DAPDH different from the sequences of other knownmeso-DAPDHs were replaced with the conserved amino acids in othermeso-DAPDHs, and assay of wild-type and mutant enzyme activities revealed that F146 and M152 are not critical in determining the enzyme's substrate specificity. The high thermostability and relaxed substrate profile ofS. thermophilum meso-DAPDH warrant it as an excellent starting enzyme for creating effectived-amino acid dehydrogenases by protein engineering.

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 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 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 Nutritional quality evaluation of Whitemouth croaker (Micropogonias furnieri) protein isolate

2014 ◽  
Vol 44 (2) ◽  
pp. 134-143
Author(s):  
William Renzo Cortez-Vega ◽  
Irene Rodrigues Freitas ◽  
Sandriane Pizato ◽  
Carlos Prentice
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Nutritional Quality ◽  
Troponin I ◽  
Essential Amino Acids ◽  
Protein Isolate ◽  
Content Type ◽  
Sds Page ◽  
Apparent Bioavailability

Purpose – The purpose of this study was to isolate Whitemouth croaker protein by alkaline solubilization process and evaluate their nutritional quality to evaluate the bioavailability of essential amino acids. Design/methodology/approach – The proximate composition, essential amino acid composition, in vitro digestibility, apparent bioavailability, chemical score of amino acids and SDS-PAGE were determined for the isolated croaker proteins. Findings – The isolated protein showed a high level of protein 92.21 percent and low amount of lipids 0.57 percent. The protein is rich in lysine and leucine, 108.73 and 96.75 mg/g protein, respectively. The protein isolate had high digestibility, 94.32 percent, which indicates proper utilization of this protein source, while the tryptophan had lower bioavailability (12.58 mg amino acid/mg protein). The high chemical scores were found for the amino acids lysine, methionine+cysteine (6.79 and 5.14). SDS-PAGE of proteins extracted showed appearance of the heavy chain of myosin (220 kDa), actin (50 kDa) and other fractions, with molecular weight between 20 and 50 kDa, such as troponin I, C and T. Originality/value – The products obtained from croaker muscle can be incorporated as a high value supplements in human diets. The isolated protein exhibited a high content of essential amino acids and digestibility, indicating that the protein has a high nutritional quality.

scholarly journals Development of a Homologous Expression System for and Systematic Site-Directed Mutagenesis Analysis of Thurincin H, a Bacteriocin Produced by Bacillus thuringiensis SF361

2014 ◽  
Vol 80 (12) ◽  
pp. 3576-3584 ◽  
Author(s):  
Gaoyan Wang ◽  
David C. Manns ◽  
John J. Churey ◽  
Randy W. Worobo
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Bacillus Thuringiensis ◽  
Gene Cluster ◽  
Expression Vector ◽  
Expression System ◽  
Structural Genes ◽  
Cry Protein ◽  
Content Type ◽  
Thurincin H

ABSTRACTThurincin H is an antimicrobial peptide produced byBacillus thuringiensisSF361. With a helical back bone, the 31 amino acids of thurincin H form a hairpin structure maintained by four pairs of very unique sulfur-to-α-carbon thioether bonds. The production of thurincin H depends on a putative gene cluster containing 10 open reading frames. The gene cluster includes three tandem structural genes (thnA1,thnA2, andthnA3) encoding three identical 40-amino-acid thurincin H prepeptides and seven other genes putatively responsible for prepeptide processing, regulation, modification, exportation, and self-immunity. A homologous thurincin H expression system was developed by transforming a thurincin H-deficient host with a novel expression vector, pGW133. The host, designatedB. thuringiensisSF361 ΔthnA1ΔthnA2ΔthnA3, was constructed by deletion of the three tandem structural genes from the chromosome of the natural thurincin H producer. The thurincin H expression vector pGW133 was constructed by cloning the thurincin H native promoter,thnA1, and a Cry protein terminator into theEscherichia coli-B. thuringiensisshuttle vector pHT315. Thirty-three different pGW133 variants, each containing a different point mutation in thethnA1gene, were generated and separately transformed intoB. thuringiensisSF361 ΔthnA1ΔthnA2ΔthnA3. Those site-directed mutants contained either a single radical or conservative amino acid substitution on the thioether linkage-forming positions or a radical substitution on all other nonalanine amino acids. The bacteriocin activities ofB. thuringiensisSF361 ΔthnA1ΔthnA2ΔthnA3carrying different pGW133 variants against three different indicator strains were subsequently compared.

scholarly journals Distinct Regioselectivity of Fungal P450 Enzymes for Steroidal Hydroxylation

2019 ◽  
Vol 85 (18) ◽  
Author(s):  
Wei Lu ◽  
Jinhui Feng ◽  
Xi Chen ◽  
Yun-Juan Bao ◽  
Yu Wang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pichia Pastoris ◽  
Organic Synthesis ◽  
Transcriptome Sequencing ◽  
Amino Acid Sequence Identity ◽  
Steroid Nucleus ◽  
Content Type ◽  
Whole Cells ◽  
Sequence Identity ◽  
High Amino Acid

ABSTRACT In this study, we identified two P450 enzymes (CYP5150AP3 and CYP5150AN1) from Thanatephorus cucumeris NBRC 6298 by combination of transcriptome sequencing and heterologous expression in Pichia pastoris. The biotransformation of 11-deoxycortisol and testosterone by Pichia pastoris whole cells coexpressing the cyp5150ap3 and por genes demonstrated that the CYP5150AP3 enzyme possessed steroidal 7β-hydroxylase activities toward these substrates, and the regioselectivity was dependent on the structures of steroidal compounds. CYP5150AN1 catalyzed the 2β-hydroxylation of 11-deoxycortisol. It is interesting that they display different regioselectivity of hydroxylation from that of their isoenzyme, CYP5150AP2, which possesses 19- and 11β-hydroxylase activities. IMPORTANCE The steroidal hydroxylases CYP5150AP3 and CYP5150AN1 together with the previously characterized CYP5150AP2 belong to the CYP5150A family of P450 enzymes with high amino acid sequence identity, but they showed completely different regioselectivities toward 11-deoxycortisol, suggesting the regioselectivity diversity of steroidal hydroxylases of CYP5150 family. They are also distinct from the known bacterial and fungal steroidal hydroxylases in substrate specificity and regioselectivity. Biocatalytic hydroxylation is one of the important transformations for the functionalization of steroid nucleus rings but remains a very challenging task in organic synthesis. These hydroxylases are useful additions to the toolbox of hydroxylase enzymes for the functionalization of steroids at various positions.

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